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Bibliography on: Holobiont

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ESP: PubMed Auto Bibliography 06 Dec 2019 at 01:31 Created: 

Holobiont

Holobionts are assemblages of different species that form ecological units. Lynn Margulis proposed that any physical association between individuals of different species for significant portions of their life history is a symbiosis. All participants in the symbiosis are bionts, and therefore the resulting assemblage was first coined a holobiont by Lynn Margulis in 1991 in the book Symbiosis as a Source of Evolutionary Innovation. Holo is derived from the Ancient Greek word ὅλος (hólos) for “whole”. The entire assemblage of genomes in the holobiont is termed a hologenome.

Created with PubMed® Query: holobiont OR hologenome NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-12-05

Walker DM, Hill AJ, Albecker MA, et al (2019)

Variation in the Slimy Salamander (Plethodon spp.) Skin and Gut-Microbial Assemblages Is Explained by Geographic Distance and Host Affinity.

Microbial ecology pii:10.1007/s00248-019-01456-x [Epub ahead of print].

A multicellular host and its microbial communities are recognized as a metaorganism-a composite unit of evolution. Microbial communities have a variety of positive and negative effects on the host life history, ecology, and evolution. This study used high-throughput amplicon sequencing to characterize the complete skin and gut microbial communities, including both bacteria and fungi, of a terrestrial salamander, Plethodon glutinosus (Family Plethodontidae). We assessed salamander populations, representing nine mitochondrial haplotypes ('clades'), for differences in microbial assemblages across 13 geographic locations in the Southeastern United States. We hypothesized that microbial assemblages were structured by both host factors and geographic distance. We found a strong correlation between all microbial assemblages at close geographic distances, whereas, as spatial distance increases, the patterns became increasingly discriminate. Network analyses revealed that gut-bacterial communities have the highest degree of connectedness across geographic space. Host salamander clade was explanatory of skin-bacterial and gut-fungal assemblages but not gut-bacterial assemblages, unless the latter were analyzed within a phylogenetic context. We also inferred the function of gut-fungal assemblages to understand how an understudied component of the gut microbiome may influence salamander life history. We concluded that dispersal limitation may in part describe patterns in microbial assemblages across space and also that the salamander host may select for skin and gut communities that are maintained over time in closely related salamander populations.

RevDate: 2019-12-05

Alex A, A Antunes (2019)

Comparative Genomics Reveals Metabolic Specificity of Endozoicomonas Isolated from a Marine Sponge and the Genomic Repertoire for Host-Bacteria Symbioses.

Microorganisms, 7(12): pii:microorganisms7120635.

The most recently described bacterial members of the genus Endozoicomonas have been found in association with a wide variety of marine invertebrates. Despite their ubiquity in the host holobiont, limited information is available on the molecular genomic signatures of the symbiotic association of Endozoicomonas with marine sponges. Here, we generated a draft genome of Endozoicomonas sp. OPT23 isolated from the intertidal marine sponge Ophlitaspongia papilla and performed comprehensive comparative genomics analyses. Genome-specific analysis and metabolic pathway comparison of the members of the genus Endozoicomonas revealed the presence of gene clusters encoding for unique metabolic features, such as the utilization of carbon sources through lactate, L-rhamnose metabolism, and a phenylacetic acid degradation pathway in Endozoicomonas sp. OPT23. Moreover, the genome harbors genes encoding for eukaryotic-like proteins, such as ankyrin repeats, tetratricopeptide repeats, and Sel1 repeats, which likely facilitate sponge-bacterium attachment. The genome also encodes major secretion systems and homologs of effector molecules that seem to enable the sponge-associated bacterium to interact with the sponge and deliver the virulence factors for successful colonization. In conclusion, the genome analysis of Endozoicomonas sp. OPT23 revealed the presence of adaptive genomic signatures that might favor their symbiotic lifestyle within the sponge host.

RevDate: 2019-12-04

Achlatis M, Pernice M, Green K, et al (2019)

Single-cell visualization indicates direct role of sponge host in uptake of dissolved organic matter.

Proceedings. Biological sciences, 286(1916):20192153.

Marine sponges are set to become more abundant in many near-future oligotrophic environments, where they play crucial roles in nutrient cycling. Of high importance is their mass turnover of dissolved organic matter (DOM), a heterogeneous mixture that constitutes the largest fraction of organic matter in the ocean and is recycled primarily by bacterial mediation. Little is known, however, about the mechanism that enables sponges to incorporate large quantities of DOM in their nutrition, unlike most other invertebrates. Here, we examine the cellular capacity for direct processing of DOM, and the fate of the processed matter, inside a dinoflagellate-hosting bioeroding sponge that is prominent on Indo-Pacific coral reefs. Integrating transmission electron microscopy with nanoscale secondary ion mass spectrometry, we track 15N- and 13C-enriched DOM over time at the individual cell level of an intact sponge holobiont. We show initial high enrichment in the filter-feeding cells of the sponge, providing visual evidence of their capacity to process DOM through pinocytosis without mediation of resident bacteria. Subsequent enrichment of the endosymbiotic dinoflagellates also suggests sharing of host nitrogenous wastes. Our results shed light on the physiological mechanism behind the ecologically important ability of sponges to cycle DOM via the recently described sponge loop.

RevDate: 2019-12-02

McIlroy SE, Cunning R, Baker AC, et al (2019)

Competition and succession among coral endosymbionts.

Ecology and evolution, 9(22):12767-12778 pii:ECE35749.

Host species often support a genetically diverse guild of symbionts, the identity and performance of which can determine holobiont fitness under particular environmental conditions. These symbiont communities are structured by a complex set of potential interactions, both positive and negative, between the host and symbionts and among symbionts. In reef-building corals, stable associations with specific symbiont species are common, and we hypothesize that this is partly due to ecological mechanisms, such as succession and competition, which drive patterns of symbiont winnowing in the initial colonization of new generations of coral recruits. We tested this hypothesis using the experimental framework of the de Wit replacement series and found that competitive interactions occurred among symbionts which were characterized by unique ecological strategies. Aposymbiotic octocoral recruits within high- and low-light environments were inoculated with one of three Symbiodiniaceae species as monocultures or with cross-paired mixtures, and we tracked symbiont uptake using quantitative genetic assays. Priority effects, in which early colonizers excluded competitive dominants, were evidenced under low light, but these early opportunistic species were later succeeded by competitive dominants. Under high light, a more consistent competitive hierarchy was established in which competitive dominants outgrew and limited the abundance of others. These findings provide insight into mechanisms of microbial community organization and symbiosis breakdown and recovery. Furthermore, transitions in competitive outcomes across spatial and temporal environmental variation may improve lifetime host fitness.

RevDate: 2019-12-03

Bana B, F Cabreiro (2019)

The Microbiome and Aging.

Annual review of genetics, 53:239-261.

Aging is a natural process of organismal decay that underpins the development of myriad diseases and disorders. Extensive efforts have been made to understand the biology of aging and its regulation, but most studies focus solely on the host organism. Considering the pivotal role of the microbiota in host health and metabolism, we propose viewing the host and its microbiota as a single biological entity whose aging phenotype is influenced by the complex interplay between host and bacterial genetics. In this review we present how the microbiota changes as the host ages, but also how the intricate relationship between host and indigenous bacteria impacts organismal aging and life span. In addition, we highlight other microbiota-dependent mechanisms that potentially regulate aging, and present experimental animal models for addressing these questions. Importantly, we propose microbiome dysbiosis as an additional hallmark and biomarker of aging.

RevDate: 2019-11-27

Kamm K, Osigus HJ, Stadler PF, et al (2019)

Genome analyses of a placozoan rickettsial endosymbiont show a combination of mutualistic and parasitic traits.

Scientific reports, 9(1):17561 pii:10.1038/s41598-019-54037-w.

Symbiotic relationships between eukaryotic hosts and bacteria range from parasitism to mutualism and may deeply influence both partners' fitness. The presence of intracellular bacteria in the metazoan phylum Placozoa has been reported several times, but without any knowledge about the nature of this relationship and possible implications for the placozoan holobiont. This information may be of crucial significance since little is known about placozoan ecology and how different species adapt to different environmental conditions, despite being almost invariable at the morphological level. We here report on the novel genome of the rickettsial endosymbiont of Trichoplax sp. H2 (strain "Panama"). The combination of eliminated and retained metabolic pathways of the bacterium indicates a potential for a mutualistic as well as for a parasitic relationship, whose outcome could depend on the environmental context. In particular we show that the endosymbiont is dependent on the host for growth and reproduction and that the latter could benefit from a supply with essential amino acids and important cofactors. These findings call for further studies to clarify the actual benefit for the placozoan host and to investigate a possible role of the endosymbiont for ecological separation between placozoan species.

RevDate: 2019-11-25

Zhang Y, Kumarasamy S, Mell B, et al (2019)

Vertical selection for nuclear and mitochondrial genomes shapes gut microbiota and modifies risks for complex diseases.

Physiological genomics [Epub ahead of print].

Here we postulate that the heritability of complex disease traits previously ascribed solely to the inheritance of the nuclear and mitochondrial genomes, is broadened to encompass a third component of the holobiome, the microbiome. To test this, we expanded on the selectively bred low capacity runner/high capacity runner (LCR/HCR) rat exercise model system into four distinct rat holobiont model frameworks including matched and mismatched host nuclear and mitochondrial genomes. Vertical selection of varying nuclear and mitochondrial genomes resulted in differential acquisition of the microbiome within each of these holobiont models. Polygenic disease risk of these novel models were assessed and subsequently correlated with patterns of acquisition and contributions of their microbiomes in controlled laboratory settings. Nuclear-mitochondrial-microbiotal interactions were not for exercise as a reporter of health, but significantly noted for increased adiposity, increased blood pressure, compromised cardiac function, and loss of long-term memory as reporters of disease susceptibility. These findings provide evidence for co-selection of the microbiome with nuclear and mitochondrial genomes as an important feature impacting the heritability of complex diseases.

RevDate: 2019-11-23

Cooke I, Mead O, Whalen C, et al (2019)

Molecular techniques and their limitations shape our view of the holobiont.

Zoology (Jena, Germany), 137:125695 pii:S0944-2006(19)30053-4 [Epub ahead of print].

It is now recognised that the biology of almost any organism cannot be fully understood without recognising the existence and potential functional importance of associated microbes. Arguably, the emergence of this holistic viewpoint may never have occurred without the development of a crucial molecular technique, 16S rDNA amplicon sequencing, which allowed microbial communities to be easily profiled across a broad range of contexts. A diverse array of molecular techniques are now used to profile microbial communities, infer their evolutionary histories, visualise them in host tissues, and measure their molecular activity. In this review, we examine each of these categories of measurement and inference with a focus on the questions they make tractable, and the degree to which their capabilities and limitations shape our view of the holobiont.

RevDate: 2019-11-22

Sweet M, Burian A, Fifer J, et al (2019)

Compositional homogeneity in the pathobiome of a new, slow-spreading coral disease.

Microbiome, 7(1):139 pii:10.1186/s40168-019-0759-6.

BACKGROUND: Coral reefs face unprecedented declines in diversity and cover, a development largely attributed to climate change-induced bleaching and subsequent disease outbreaks. Coral-associated microbiomes may strongly influence the fitness of their hosts and alter heat tolerance and disease susceptibility of coral colonies. Here, we describe a new coral disease found in Micronesia and present a detailed assessment of infection-driven changes in the coral microbiome.

RESULTS: Combining field monitoring and histological, microscopic and next-generation barcoding assessments, we demonstrate that the outbreak of the disease, named 'grey-patch disease', is associated with the establishment of cyanobacterial biofilm overgrowing coral tissue. The disease is characterised by slow progression rates, with coral tissue sometimes growing back over the GPD biofilm. Network analysis of the corals' microbiome highlighted the clustering of specific microbes which appeared to benefit from the onset of disease, resulting in the formation of 'infection clusters' in the microbiomes of apparently healthy corals.

CONCLUSIONS: Our results appear to be in contrast to the recently proposed Anna-Karenina principle, which states that disturbances (such as disease) trigger chaotic dynamics in microbial communities and increase β-diversity. Here, we show significantly higher community similarity (compositional homogeneity) in the pathobiome of diseased corals, compared to the microbiome associated with apparently healthy tissue. A possible explanation for this pattern is strong competition between the pathogenic community and those associated with the 'healthy' coral holobiont, homogenising the composition of the pathobiome. Further, one of our key findings is that multiple agents appear to be involved in degrading the corals' defences causing the onset of this disease. This supports recent findings indicating a need for a shift from the one-pathogen-one-disease paradigm to exploring the importance of multiple pathogenic players in any given disease.

RevDate: 2019-11-19

Li Y, Tassia MG, Waits DS, et al (2019)

Genomic adaptations to chemosymbiosis in the deep-sea seep-dwelling tubeworm Lamellibrachia luymesi.

BMC biology, 17(1):91 pii:10.1186/s12915-019-0713-x.

BACKGROUND: Symbiotic relationships between microbes and their hosts are widespread and diverse, often providing protection or nutrients, and may be either obligate or facultative. However, the genetic mechanisms allowing organisms to maintain host-symbiont associations at the molecular level are still mostly unknown, and in the case of bacterial-animal associations, most genetic studies have focused on adaptations and mechanisms of the bacterial partner. The gutless tubeworms (Siboglinidae, Annelida) are obligate hosts of chemoautotrophic endosymbionts (except for Osedax which houses heterotrophic Oceanospirillales), which rely on the sulfide-oxidizing symbionts for nutrition and growth. Whereas several siboglinid endosymbiont genomes have been characterized, genomes of hosts and their adaptations to this symbiosis remain unexplored.

RESULTS: Here, we present and characterize adaptations of the cold seep-dwelling tubeworm Lamellibrachia luymesi, one of the longest-lived solitary invertebrates. We sequenced the worm's ~ 688-Mb haploid genome with an overall completeness of ~ 95% and discovered that L. luymesi lacks many genes essential in amino acid biosynthesis, obligating them to products provided by symbionts. Interestingly, the host is known to carry hydrogen sulfide to thiotrophic endosymbionts using hemoglobin. We also found an expansion of hemoglobin B1 genes, many of which possess a free cysteine residue which is hypothesized to function in sulfide binding. Contrary to previous analyses, the sulfide binding mediated by zinc ions is not conserved across tubeworms. Thus, the sulfide-binding mechanisms in sibgolinids need to be further explored, and B1 globins might play a more important role than previously thought. Our comparative analyses also suggest the Toll-like receptor pathway may be essential for tolerance/sensitivity to symbionts and pathogens. Several genes related to the worm's unique life history which are known to play important roles in apoptosis, cell proliferation, and aging were also identified. Last, molecular clock analyses based on phylogenomic data suggest modern siboglinid diversity originated in 267 mya (± 70 my) support previous hypotheses indicating a Late Mesozoic or Cenozoic origins of approximately 50-126 mya for vestimentiferans.

CONCLUSIONS: Here, we elucidate several specific adaptations along various molecular pathways that link phenome to genome to improve understanding of holobiont evolution. Our findings of adaptation in genomic mechanisms to reducing environments likely extend to other chemosynthetic symbiotic systems.

RevDate: 2019-11-15

Mitter B, Brader G, Pfaffenbichler N, et al (2019)

Next generation microbiome applications for crop production - limitations and the need of knowledge-based solutions.

Current opinion in microbiology, 49:59-65 pii:S1369-5274(19)30040-2 [Epub ahead of print].

Plants are associated with highly diverse microbiota, which are crucial partners for their host carrying out important functions. Essentially, they are involved in nutrient supply, pathogen antagonism and protection of their host against different types of stress. The potential of microbial inoculants has been demonstrated in numerous studies, primarily under greenhouse conditions. However, field application, for example, as biofertilizer or biocontrol agent, is still a challenge as the applied microorganisms often are not provided in sufficiently high cell numbers, are rapidly outcompeted and cannot establish or require specific conditions to mediate the desired effects. We still have limited understanding on the fate of inoculants and on holobiont interactions, that is, interactions between plants, micro-biota and macro-biota and the environment, under field conditions. A better understanding will provide the basis for establishing models predicting the behaviour of strains or consortia and will help identifying microbiome members being able to establish and to mediate desired effects under certain conditions. Such models may also inform about the best management practices modulating microbiota in a desired way. Also, smart delivery approaches of microbial inoculants as well as the selection or breeding of plant genotypes better able to interact with microbiota may represent promising avenues.

RevDate: 2019-11-14

Sauvage T, Schmidt WE, Yoon HS, et al (2019)

Promising prospects of nanopore sequencing for algal hologenomics and structural variation discovery.

BMC genomics, 20(1):850 pii:10.1186/s12864-019-6248-2.

BACKGROUND: The MinION Access Program (MAP, 2014-2016) allowed selected users to test the prospects of long nanopore reads for diverse organisms and applications through the rapid development of improving chemistries. In 2014, faced with a fragmented Illumina assembly for the chloroplast genome of the green algal holobiont Caulerpa ashmeadii, we applied to the MAP to test the prospects of nanopore reads to investigate such intricacies, as well as further explore the hologenome of this species with native and hybrid approaches.

RESULTS: The chloroplast genome could only be resolved as a circular molecule in nanopore assemblies, which also revealed structural variants (i.e. chloroplast polymorphism or heteroplasmy). Signal and Illumina polishing of nanopore-assembled organelle genomes (chloroplast and mitochondrion) reflected the importance of coverage on final quality and current limitations. In hybrid assembly, our modest nanopore data sets showed encouraging results to improve assembly length, contiguity, repeat content, and binning of the larger nuclear and bacterial genomes. Profiling of the holobiont with nanopore or Illumina data unveiled a dominant Rhodospirillaceae (Alphaproteobacteria) species among six putative endosymbionts. While very fragmented, the cumulative hybrid assembly length of C. ashmeadii's nuclear genome reached 24.4 Mbp, including 2.1 Mbp in repeat, ranging closely with GenomeScope's estimate (> 26.3 Mbp, including 4.8 Mbp in repeat).

CONCLUSION: Our findings relying on a very modest number of nanopore R9 reads as compared to current output with newer chemistries demonstrate the promising prospects of the technology for the assembly and profiling of an algal hologenome and resolution of structural variation. The discovery of polymorphic 'chlorotypes' in C. ashmeadii, most likely mediated by homing endonucleases and/or retrohoming by reverse transcriptases, represents the first report of chloroplast heteroplasmy in the siphonous green algae. Improving contiguity of C. ashmeadii's nuclear and bacterial genomes will require deeper nanopore sequencing to greatly increase the coverage of these larger genomic compartments.

RevDate: 2019-11-11

Collens A, Kelley E, LA Katz (2019)

The concept of the hologenome, an epigenetic phenomenon, challenges aspects of the modern evolutionary synthesis.

Journal of experimental zoology. Part B, Molecular and developmental evolution [Epub ahead of print].

John Tyler Bonner's call to re-evaluate evolutionary theory in light of major transitions in life on Earth (e.g., from the first origins of microbial life to the evolution of sex, and the origins of multicellularity) resonate with recent discoveries on epigenetics and the concept of the hologenome. Current studies of genome evolution often mistakenly focus only on the inheritance of DNA between parent and offspring. These are in line with the widely accepted Neo-Darwinian framework that pairs Mendelian genetics with an emphasis on natural selection as explanations for the evolution of biodiversity on Earth. Increasing evidence for widespread symbioses complicates this narrative, as is seen in Scott Gilbert's discussion of the concept of the holobiont in this series: Organisms across the tree of life coexist with substantial influence on one another through endosymbiosis, symbioses, and host-associated microbiomes. The holobiont theory, coupled with observations from molecular studies, also requires us to understand genomes in a new way-by considering the interactions underlain by the genome of a host plus its associated microbes, a conglomerate entity referred to as the hologenome. We argue that the complex patterns of inheritance of these genomes coupled with the influence of symbionts on host gene expression make the concept of the hologenome an epigenetic phenomenon. We further argue that the aspects of the hologenome challenge of the modern evolutionary synthesis, which requires updating to remain consistent with Darwin's intent of providing natural laws that underlie the evolution of life on Earth.

RevDate: 2019-11-11

Lucaciu R, Pelikan C, Gerner SM, et al (2019)

A Bioinformatics Guide to Plant Microbiome Analysis.

Frontiers in plant science, 10:1313.

Recent evidence for intimate relationship of plants with their microbiota shows that plants host individual and diverse microbial communities that are essential for their survival. Understanding their relatedness using genome-based and high-throughput techniques remains a hot topic in microbiome research. Molecular analysis of the plant holobiont necessitates the application of specific sampling and preparatory steps that also consider sources of unwanted information, such as soil, co-amplified plant organelles, human DNA, and other contaminations. Here, we review state-of-the-art and present practical guidelines regarding experimental and computational aspects to be considered in molecular plant-microbiome studies. We discuss sequencing and "omics" techniques with a focus on the requirements needed to adapt these methods to individual research approaches. The choice of primers and sequence databases is of utmost importance for amplicon sequencing, while the assembly and binning of shotgun metagenomic sequences is crucial to obtain quality data. We discuss specific bioinformatic workflows to overcome the limitation of genome database resources and for covering large eukaryotic genomes such as fungi. In transcriptomics, it is necessary to account for the separation of host mRNA or dual-RNAseq data. Metaproteomics approaches provide a snapshot of the protein abundances within a plant tissue which requires the knowledge of complete and well-annotated plant genomes, as well as microbial genomes. Metabolomics offers a powerful tool to detect and quantify small molecules and molecular changes at the plant-bacteria interface if the necessary requirements with regard to (secondary) metabolite databases are considered. We highlight data integration and complementarity which should help to widen our understanding of the interactions among individual players of the plant holobiont in the future.

RevDate: 2019-11-08

Staples R, LaDuca RL, Roze LV, et al (2019)

Structure and chemical analysis of major specialized metabolites produced by the lichen Evernia prunastri.

Chemistry & biodiversity [Epub ahead of print].

We performed comparative profiling of four specialized metabolites in the lichen Evernia prunastri, collected at three different geographic locations, California and Maine, USA, and Yoshkar Ola, Mari El, Russia. Among the compounds produced at high concentrations that were identified in all three specimens, evernic acid, usnic acid, lecanoric acid and chloroatranorin, evernic acid was the most abundant. Two depsidones, salazinic acid and physodic acid, were detected in the Yoshkar-Ola collection only. The crystalline structure of evernic acid (2-hydroxy-4-[(2-hydroxy-4-methoxy-6-methylbenzoyl) oxy]-6-methylbenzoate) (hmb) revealed two crystallographically and conformationally distinct hmb anions, along with two monovalent sodium atoms. One hmb moiety contained an exotetradentate binding mode to sodium, whereas the other exhibited an exohexadentate binding mode to sodium. Embedded edge-sharing {Na2O8}n sodium-oxygen chains connected the hmb anions into the full three-dimensional crystal structure of the title compound. The crystal used for single-crystal x-ray diffraction exhibited non-merohedral twinning. The data suggest the importance of the acetyl-polymalonyl pathway products to processes of maintaining integrity of the lichen holobiont community.

RevDate: 2019-11-08

Weishaar R, Wellmann R, Camarinha-Silva A, et al (2019)

Selecting the hologenome to breed for an improved feed efficiency in pigs-A novel selection index.

Journal of animal breeding and genetics = Zeitschrift fur Tierzuchtung und Zuchtungsbiologie [Epub ahead of print].

Most traits in animal breeding, including feed efficiency traits in pigs, are affected by many genes with small effect and have a moderately high heritability between 0.1 and 0.5, which enables efficient selection. Since the microbiota composition in the gastrointestinal tract is also partly heritable and was shown to have a substantial effect on feed efficiency, the host genes affect the phenotype not only directly by altering metabolic pathways, but also indirectly by changing the microbiota composition. The effect m i of the microbiota composition on the breeding value g i of an animal i is the conditional expectation of its breeding value, given the vector φ i with microbiota frequencies, that is m i = E g i | φ i . The breeding value g i of an animal can therefore be decomposed into a heritable contribution m i that arises from an altered microbiota composition and a heritable contribution p i that arises from altered metabolic pathways within the animal, so g i = m i + p i . Instead of selecting for breeding value g ^ i , an index comprising the two components m ^ i and p ^ i with appropriate weights, that is I i = λ 1 m ^ i + λ 2 p ^ i , can be used. The present study shows how this breeding strategy can be applied in pig genomic selection breeding scheme for two feed efficiency traits and daily gain.

RevDate: 2019-11-06

Alves Monteiro HJ, Brahmi C, Mayfield AB, et al (2019)

Molecular mechanisms of acclimation to long-term elevated temperature exposure in marine symbioses.

Global change biology [Epub ahead of print].

Seawater temperature rise in French Polynesia has repeatedly resulted in the bleaching of corals and giant clams. Because giant clams possess distinctive ectosymbiotic features, they represent a unique and powerful model for comparing molecular pathways involved in 1) maintenance of symbiosis and 2) acquisition of thermo-tolerance among coral reef organisms. Herein, we explored the physiological and transcriptomic responses of the clam hosts and their photosynthetically active symbionts over a 65-day experiment in which clams were exposed to either normal or environmentally relevant elevated seawater temperatures. Additionally, we used metabarcoding data coupled with in situ sampling/survey data to explore the relative importance of holobiont adaptation (i.e., a symbiont community shift) versus acclimation (i.e., physiological changes at the molecular level) in the clams' responses to environmental change. We finally compared transcriptomic data to publicly available genomic datasets for Symbiodiniaceae dinoflagellates (both cultured and in hospite with the coral Pocillopora damicornis) to better tease apart the responses of both hosts and specific symbiont genotypes in this mutualistic association. Gene module preservation analysis revealed that the function of the symbionts' photosystem II was impaired at high temperature, and this response was also found across all holobionts and Symbiodiniaceae lineages examined. Similarly, epigenetic modulation appeared to be a key response mechanism for symbionts in hospite with giant clams exposed to high temperatures, and such modulation was able to distinguish thermo-tolerant from thermo-sensitive Cladocopium goreaui ecotypes; epigenetic processes may, then, represent a promising research avenue for those interested in coral reef conservation in this era of changing global climate.

RevDate: 2019-10-26

Newbold LK, Robinson A, Rasnaca I, et al (2019)

Genetic, epigenetic and microbiome characterisation of an earthworm species (Octolasion lacteum) along a radiation exposure gradient at Chernobyl.

Environmental pollution (Barking, Essex : 1987), 255(Pt 1):113238 pii:S0269-7491(19)33044-1 [Epub ahead of print].

The effects of exposure to different levels of ionising radiation were assessed on the genetic, epigenetic and microbiome characteristics of the "hologenome" of earthworms collected at sites within the Chernobyl exclusion zone (CEZ). The earthworms Aporrectodea caliginosa (Savigny, 1826) and Octolasion lacteum (Örley, 1881) were the two species that were most frequently found at visited sites, however, only O. lacteum was present at sufficient number across different exposure levels to enable comparative hologenome analysis. The identification of morphotype O. lacteum as a probable single clade was established using a combination of mitochondrial (cytochrome oxidase I) and nuclear genome (Amplified Fragment Length Polymorphism (AFLP) using MspI loci). No clear site associated differences in population genetic structure was found between populations using the AFLP marker loci. Further, no relationship between ionising radiation exposure levels and the percentage of methylated loci or pattern of distribution of DNA methylation marks was found. Microbiome structure was clearly site dependent, with gut microbiome community structure and diversity being systematically associated with calculated site-specific earthworm dose rates. There was, however, also co-correlation between earthworm dose rates and other soil properties, notably soil pH; a property known to affect soil bacterial community structure. Such co-correlation means that it is not possible to attribute microbiome changes unequivocally to radionuclide exposure. A better understanding of the relationship between radionuclide exposure soil properties and their interactions on bacterial microbiome community response is, therefore, needed to establish whether these the observed microbiome changes are attributed directly to radiation exposure, other soil properties or to an interaction between multiple variables at sites within the CEZ.

RevDate: 2019-10-25

Le Pennec G, EA Gall (2019)

The microbiome of Codium tomentosum: original state and in the presence of copper.

World journal of microbiology & biotechnology, 35(11):167 pii:10.1007/s11274-019-2740-8.

Codium tomentosum, as all organisms, hosts transiently and permanently numerous microorganisms. These holobionts can undergo environmental pressures influencing both partners creating modifications/imbalances within the associations, which may directly influence their physiological status by selecting tolerant bacteria. Furthermore, the capability of remediation of the associated bacterioflora, in particular of metallic trace elements, may provide the host with survival potential in polluted environments. In this context, we incubated C. tomentosum thalli in the presence of copper and studied its influence on the reference bacteriome. Whatever the concentration of copper, no shift was evidenced on the bacteriome at the phylum level. However, a high copper concentration enriched the bacteriome of C. tomentosum in both the genera Clostridium and Pseudolteromonas.

RevDate: 2019-10-23

Stothart MR, Palme R, AEM Newman (2019)

It's what's on the inside that counts: stress physiology and the bacterial microbiome of a wild urban mammal.

Proceedings. Biological sciences, 286(1913):20192111.

The microbiome's capacity to shape the host phenotype and its mutability underlie theorization that the microbiome might facilitate host acclimation to rapid environmental change. However, when environmental change occurs, it is unclear whether resultant microbiome restructuring is proximately driven by this changing external environment or by the host's physiological response to this change. We leveraged urbanization to compare the ability of host environment (urban or forest) versus multi-scale biological measures of host hypothalamic-pituitary-adrenal (HPA) axis physiology (neutrophil : lymphocyte ratio, faecal glucocorticoid metabolites, hair cortisol) to explain variation in the eastern grey squirrel (Sciurus carolinensis) faecal microbiome. Urban and forest squirrels differed across all three of the interpretations of HPA axis activity we measured. Direct consideration of these physiological measures better explained greater phylogenetic turnover between squirrels than environment. This pattern was strongly driven by trade-offs between bacteria which specialize on metabolizing digesta versus host-derived nutrient sources. Drawing on ecological theory to explain patterns in intestinal bacterial communities, we conclude that although environmental change can affect the microbiome, it might primarily do so indirectly by altering host physiology. We demonstrate that the inclusion and careful consideration of dynamic, rather than fixed (e.g. sex), dimensions of host physiology are essential for the study of host-microbe symbioses at the micro-evolutionary scale.

RevDate: 2019-10-22

Trevathan-Tackett SM, Sherman CDH, Huggett MJ, et al (2019)

A horizon scan of priorities for coastal marine microbiome research.

Nature ecology & evolution pii:10.1038/s41559-019-0999-7 [Epub ahead of print].

Research into the microbiomes of natural environments is changing the way ecologists and evolutionary biologists view the importance of microorganisms in ecosystem function. This is particularly relevant in ocean environments, where microorganisms constitute the majority of biomass and control most of the major biogeochemical cycles, including those that regulate Earth's climate. Coastal marine environments provide goods and services that are imperative to human survival and well-being (for example, fisheries and water purification), and emerging evidence indicates that these ecosystem services often depend on complex relationships between communities of microorganisms (the 'microbiome') and the environment or their hosts - termed the 'holobiont'. Understanding of coastal ecosystem function must therefore be framed under the holobiont concept, whereby macroorganisms and their associated microbiomes are considered as a synergistic ecological unit. Here, we evaluate the current state of knowledge on coastal marine microbiome research and identify key questions within this growing research area. Although the list of questions is broad and ambitious, progress in the field is increasing exponentially, and the emergence of large, international collaborative networks and well-executed manipulative experiments are rapidly advancing the field of coastal marine microbiome research.

RevDate: 2019-10-21

Liu C, Cheng SH, S Lin (2019)

Illuminating the dark depths inside coral.

Cellular microbiology [Epub ahead of print].

The ability to observe in situ 3D distribution and dynamics of endosymbionts in corals is crucial for gaining a mechanistic understanding of coral bleaching and reef degradation. Here, we report the development of a tissue clearing (TC)-coupled light sheet fluorescence microscopy (LSFM) method for 3D imaging of the coral holobiont at single-cell resolution. The initial applications have demonstrated the ability of this technique to provide high space-resolution quantitative information of endosymbiont abundance and distribution within corals. With specific fluorescent probes or assays, TC-LSFM also revealed spatial distribution and dynamics of physiological conditions (such as cell proliferation, apoptosis, and hypoxia response) in both corals and their endosymbionts. This tool is highly promising for in situ and in-depth data acquisition to illuminate coral symbiosis and health conditions in the changing marine environment, providing fundamental information for coral reef conservation and restoration.

RevDate: 2019-10-15

Fiori J, Turroni S, Candela M, et al (2019)

Assessment of gut microbiota fecal metabolites by chromatographic targeted approaches.

Journal of pharmaceutical and biomedical analysis, 177:112867 pii:S0731-7085(19)31640-1 [Epub ahead of print].

Gut microbiota, the specific microbial community of the gastrointestinal tract, by means of the production of microbial metabolites provides the host with several functions affecting metabolic and immunological homeostasis. Insights into the intricate relationships between gut microbiota and the host require not only the understanding of its structure and function but also the measurement of effector molecules acting along the gut microbiota axis. This article reviews the literature on targeted chromatographic approaches in analysis of gut microbiota specific metabolites in feces as the most accessible biological matrix which can directly probe the connection between intestinal bacteria and the (patho)physiology of the holobiont. Together with a discussion on sample collection and preparation, the chromatographic methods targeted to determination of some classes of microbiota-derived metabolites (e.g., short-chain fatty acids, bile acids, low molecular masses amines and polyamines, vitamins, neurotransmitters and related compounds) are discussed and their main characteristics, summarized in Tables.

RevDate: 2019-10-11

Wada N, Ishimochi M, Matsui T, et al (2019)

Characterization of coral-associated microbial aggregates (CAMAs) within tissues of the coral Acropora hyacinthus.

Scientific reports, 9(1):14662 pii:10.1038/s41598-019-49651-7.

Bacterial diversity associated with corals has been studied extensively, however, localization of bacterial associations within the holobiont is still poorly resolved. Here we provide novel insight into the localization of coral-associated microbial aggregates (CAMAs) within tissues of the coral Acropora hyacinthus. In total, 318 and 308 CAMAs were characterized via histological and fluorescent in situ hybridization (FISH) approaches respectively, and shown to be distributed extensively throughout coral tissues collected from five sites in Japan and Australia. The densities of CAMAs within the tissues were negatively correlated with the distance from the coastline (i.e. lowest densities at offshore sites). CAMAs were randomly distributed across the six coral tissue regions investigated. Within each CAMA, bacterial cells had similar morphological characteristics, but bacterial morphologies varied among CAMAs, with at least five distinct types identified. Identifying the location of microorganisms associated with the coral host is a prerequisite for understanding their contributions to fitness. Localization of tissue-specific communities housed within CAMAs is particularly important, as these communities are potentially important contributors to vital metabolic functions of the holobiont.

RevDate: 2019-10-10

Leigh BA (2019)

Cooperation among Conflict: Prophages Protect Bacteria from Phagocytosis.

Cell host & microbe, 26(4):450-452.

Bacteriophages, viruses that infect bacteria, are the most abundant biological entities within the holobiont. In this issue of Cell Host & Microbe, Jahn et al. (2019) describe a group of phages that can suppress immune cell function in marine sponges using secreted ankyrin proteins. They call these phages Ankyphages.

RevDate: 2019-10-09

Walker NS, Fernández R, Sneed JM, et al (2019)

Differential Gene Expression during Substrate Probing in Larvae of the Caribbean Coral Porites astreoides.

Molecular ecology [Epub ahead of print].

The transition from larva to adult is a critical step in the life history strategy of most marine animals. However, the genetic basis of this life history change remains poorly understood in many taxa, including most coral species. Recent evidence suggests that coral planula larvae undergo significant changes at the physiological and molecular levels throughout development. To investigate this, we characterized differential gene expression (DGE) during the transition from planula to adult polyp in the abundant Caribbean reef-building coral Porites astreoides: i.e., from non-probing to actively substrate-probing larva, a stage required for colony initiation. This period is crucial for the coral, because it demonstrates preparedness to locate appropriate substrata for settlement based on vital environmental cues. Through RNA-Seq we identified 860 differentially expressed holobiont genes between probing and non-probing larvae (P ≤ 0.01), the majority of which were upregulated in probing larvae. Surprisingly, differentially expressed genes of endosymbiotic dinoflagellate origin greatly outnumbered coral genes, compared to a nearly 1:1 ratio of coral-to-dinoflagellate gene representation in the holobiont transcriptome. This unanticipated result suggests that dinoflagellate endosymbionts may play a significant role in the transition from non-probing to probing behavior in dinoflagellate-rich larvae. Putative holobiont genes were largely involved in protein and nucleotide binding, metabolism, and transport. Genes were also linked to environment sensing and response and integral signaling pathways. Our results thus provide detailed insight into molecular changes prior to larval settlement and highlight the complex physiological and biochemical changes that occur in early transition stages from pelagic to benthic stages in corals, and perhaps more importantly, in their endosymbionts.

RevDate: 2019-10-09

Yang Y, Sun J, Sun Y, et al (2019)

Genomic, transcriptomic, and proteomic insights into the symbiosis of deep-sea tubeworm holobionts.

The ISME journal pii:10.1038/s41396-019-0520-y [Epub ahead of print].

Deep-sea hydrothermal vents and methane seeps are often densely populated by animals that host chemosynthetic symbiotic bacteria, but the molecular mechanisms of such host-symbiont relationship remain largely unclear. We characterized the symbiont genome of the seep-living siboglinid Paraescarpia echinospica and compared seven siboglinid-symbiont genomes. Our comparative analyses indicate that seep-living siboglinid endosymbionts have more virulence traits for establishing infections and modulating host-bacterium interaction than the vent-dwelling species, and have a high potential to resist environmental hazards. Metatranscriptome and metaproteome analyses of the Paraescarpia holobiont reveal that the symbiont is highly versatile in its energy use and efficient in carbon fixation. There is close cooperation within the holobiont in production and supply of nutrients, and the symbiont may be able to obtain nutrients from host cells using virulence factors. Moreover, the symbiont is speculated to have evolved strategies to mediate host protective immunity, resulting in weak expression of host innate immunity genes in the trophosome. Overall, our results reveal the interdependence of the tubeworm holobiont through mutual nutrient supply, a pathogen-type regulatory mechanism, and host-symbiont cooperation in energy utilization and nutrient production, which is a key adaptation allowing the tubeworm to thrive in deep-sea chemosynthetic environments.

RevDate: 2019-09-30

Freire I, Gutner-Hoch E, Muras A, et al (2019)

The effect of bacteria on planula-larvae settlement and metamorphosis in the octocoral Rhytisma fulvum fulvum.

PloS one, 14(9):e0223214 pii:PONE-D-19-17240.

While increasing evidence supports a key role of bacteria in coral larvae settlement and development, the relative importance of environmentally-acquired versus vertically-transferred bacterial population is not clear. Here we have attempted to elucidate the role of post-brooding-acquired bacteria on the development of planula-larvae of the octocoral Rhytisma f. fulvum, in an in vitro cultivation system employing different types of filtered (FSW) and autoclaved (ASW) seawater and with the addition of native bacteria. A good development of larvae was obtained in polystyrene 6-well cell culture plates in the absence of natural reef substrata, achieving a 60-80% of larvae entering metamorphosis after 32 days, even in bacteria-free seawater, indicating that the bacteria acquired during the brooding period are sufficient to support planulae development. No significant difference in planulae attachment and development was observed when using 0.45 μm or 0.22 μm FSW, although autoclaving the 0.45 μm FSW negatively affected larval development, indicating the presence of beneficial bacteria. Autoclaving the different FSW homogenized the development of the larvae among the different treatments. The addition of bacterial strains isolated from the different FSW did not cause any significant effect on planulae development, although some specific strains of the genus Alteromonas seem to be beneficial for larvae development. Light was beneficial for planulae development after day 20, although no Symbiodinium cells could be observed, indicating either that light acts as a positive cue for larval development or the presence of beneficial phototrophic bacteria in the coral microbiome. The feasibility of obtaining advanced metamorphosed larvae in sterilized water provides an invaluable tool for studying the physiological role of the bacterial symbionts in the coral holobiont and the specificity of bacteria-coral interactions.

RevDate: 2019-09-30

Gilbert SF (2019)

Evolutionary transitions revisited: Holobiont evo-devo.

Journal of experimental zoology. Part B, Molecular and developmental evolution [Epub ahead of print].

John T. Bonner lists four essential transformations in the evolution of life: the emergence of the eukaryotic cell, meiosis, multicellularity, and the nervous system. This paper analyses the mechanisms for those transitions in light of three of Dr. Bonner's earlier hypotheses: (a) that the organism is its life cycle, (b) that evolution consists of alterations of the life cycle, and (c) that development extends beyond the body and into interactions with other organisms. Using the notion of the holobiont life cycle, this paper attempts to show that these evolutionary transitions can be accomplished through various means of symbiosis. Perceiving the organism both as an interspecies consortium and as a life cycle supports a twofold redefinition of the organism as a holobiont constructed by integrating together the life cycles of several species. These findings highlight the importance of symbiosis and the holobiont development in analyses of evolution.

RevDate: 2019-09-30

Bordoni B, Simonelli M, B Morabito (2019)

The Fascial Breath.

Cureus, 11(7):e5208.

The word diaphragm comes from the Greek (διάϕραγμα), which meant something that divides, but also expressed a concept related to emotions and intellect. Breath is part of a concept of symmorphosis, that is the maximum ability to adapt to multiple functional questions in a defined biological context. The act of breathing determines and defines our holobiont: how we react and who we are. The article reviews the fascial structure that involves and forms the diaphragm muscle with the aim of changing the vision of this complex muscle: from an anatomical and mechanistic form to a fractal and asynchronous form. Another step forward for understanding the diaphragm muscle is that it is not only covered, penetrated and made up of connective tissue, but the contractile tissue itself is a fascial tissue with the same embryological derivation. All the diaphragm muscle is fascia.

RevDate: 2019-09-24

Robbins SJ, Singleton CM, Chan CX, et al (2019)

A genomic view of the reef-building coral Porites lutea and its microbial symbionts.

Nature microbiology pii:10.1038/s41564-019-0532-4 [Epub ahead of print].

Corals and the reef ecosystems that they support are in global decline due to increasing anthropogenic pressures such as climate change1. However, effective reef conservation strategies are hampered by a limited mechanistic understanding of coral biology and the functional roles of the diverse microbial communities that underpin coral health2,3. Here, we present an integrated genomic characterization of the coral species Porites lutea and its microbial partners. High-quality genomes were recovered from P. lutea, as well as a metagenome-assembled Cladocopium C15 (the dinoflagellate symbiont) and 52 bacterial and archaeal populations. Comparative genomic analysis revealed that many of the bacterial and archaeal genomes encode motifs that may be involved in maintaining association with the coral host and in supplying fixed carbon, B-vitamins and amino acids to their eukaryotic partners. Furthermore, mechanisms for ammonia, urea, nitrate, dimethylsulfoniopropionate and taurine transformation were identified that interlink members of the holobiont and may be important for nutrient acquisition and retention in oligotrophic waters. Our findings demonstrate the critical and diverse roles that microorganisms play within the coral holobiont and underscore the need to consider all of the components of the holobiont if we are to effectively inform reef conservation strategies.

RevDate: 2019-09-24

van Vliet S, M Doebeli (2019)

The role of multilevel selection in host microbiome evolution.

Proceedings of the National Academy of Sciences of the United States of America pii:1909790116 [Epub ahead of print].

Animals are associated with a microbiome that can affect their reproductive success. It is, therefore, important to understand how a host and its microbiome coevolve. According to the hologenome concept, hosts and their microbiome form an integrated evolutionary entity, a holobiont, on which selection can potentially act directly. However, this view is controversial, and there is an active debate on whether the association between hosts and their microbiomes is strong enough to allow for selection at the holobiont level. Much of this debate is based on verbal arguments, but a quantitative framework is needed to investigate the conditions under which selection can act at the holobiont level. Here, we use multilevel selection theory to develop such a framework. We found that selection at the holobiont level can in principle favor a trait that is costly to the microbes but that provides a benefit to the host. However, such scenarios require rather stringent conditions. The degree to which microbiome composition is heritable decays with time, and selection can only act at the holobiont level when this decay is slow enough, which occurs when vertical transmission is stronger than horizontal transmission. Moreover, the host generation time has to be short enough compared with the timescale of the evolutionary dynamics at the microbe level. Our framework thus allows us to quantitatively predict for what kind of systems selection could act at the holobiont level.

RevDate: 2019-09-24

Kormas KA (2019)

Editorial for the Special Issue: Gut Microorganisms of Aquatic Animals.

Microorganisms, 7(10): pii:microorganisms7100377.

Since the introduction of the term holobiont [...].

RevDate: 2019-09-23

Planes S, Allemand D, Agostini S, et al (2019)

The Tara Pacific expedition-A pan-ecosystemic approach of the "-omics" complexity of coral reef holobionts across the Pacific Ocean.

PLoS biology, 17(9):e3000483 pii:PBIOLOGY-D-19-01199 [Epub ahead of print].

Coral reefs are the most diverse habitats in the marine realm. Their productivity, structural complexity, and biodiversity critically depend on ecosystem services provided by corals that are threatened because of climate change effects-in particular, ocean warming and acidification. The coral holobiont is composed of the coral animal host, endosymbiotic dinoflagellates, associated viruses, bacteria, and other microeukaryotes. In particular, the mandatory photosymbiosis with microalgae of the family Symbiodiniaceae and its consequences on the evolution, physiology, and stress resilience of the coral holobiont have yet to be fully elucidated. The functioning of the holobiont as a whole is largely unknown, although bacteria and viruses are presumed to play roles in metabolic interactions, immunity, and stress tolerance. In the context of climate change and anthropogenic threats on coral reef ecosystems, the Tara Pacific project aims to provide a baseline of the "-omics" complexity of the coral holobiont and its ecosystem across the Pacific Ocean and for various oceanographically distinct defined areas. Inspired by the previous Tara Oceans expeditions, the Tara Pacific expedition (2016-2018) has applied a pan-ecosystemic approach on coral reefs throughout the Pacific Ocean, drawing an east-west transect from Panama to Papua New Guinea and a south-north transect from Australia to Japan, sampling corals throughout 32 island systems with local replicates. Tara Pacific has developed and applied state-of-the-art technologies in very-high-throughput genetic sequencing and molecular analysis to reveal the entire microbial and chemical diversity as well as functional traits associated with coral holobionts, together with various measures on environmental forcing. This ambitious project aims at revealing a massive amount of novel biodiversity, shedding light on the complex links between genomes, transcriptomes, metabolomes, organisms, and ecosystem functions in coral reefs and providing a reference of the biological state of modern coral reefs in the Anthropocene.

RevDate: 2019-09-23

Pootakham W, Mhuantong W, Yoocha T, et al (2019)

Heat-induced shift in coral microbiome reveals several members of the Rhodobacteraceae family as indicator species for thermal stress in Porites lutea.

MicrobiologyOpen [Epub ahead of print].

The coral holobiont is a complex ecosystem consisting of coral animals and a highly diverse consortium of associated microorganisms including algae, fungi, and bacteria. Several studies have highlighted the importance of coral-associated bacteria and their potential roles in promoting the host fitness and survival. Recently, dynamics of coral-associated microbiomes have been demonstrated to be linked to patterns of coral heat tolerance. Here, we examined the effect of elevated seawater temperature on the structure and diversity of bacterial populations associated with Porites lutea, using full-length 16S rRNA sequences obtained from Pacific Biosciences circular consensus sequencing. We observed a significant increase in alpha diversity indices and a distinct shift in microbiome composition during thermal stress. There was a marked decline in the apparent relative abundance of Gammaproteobacteria family Endozoicomonadaceae after P. lutea had been exposed to elevated seawater temperature. Concomitantly, the bacterial community structure shifted toward the predominance of Alphaproteobacteria family Rhodobacteraceae. Interestingly, we did not observe an increase in relative abundance of Vibrio-related sequences in our heat-stressed samples even though the appearance of Vibrio spp. has often been detected in parallel with the increase in the relative abundance of Rhodobacteraceae during thermal bleaching in other coral species. The ability of full-length 16S rRNA sequences in resolving taxonomic uncertainty of associated bacteria at a species level enabled us to identify 24 robust indicator bacterial species for thermally stressed corals. It is worth noting that the majority of those indicator species were members of the family Rhodobacteraceae. The comparison of bacterial community structure and diversity between corals in ambient water temperature and thermally stressed corals may provide a better understanding on how bacteria symbionts contribute to the resilience of their coral hosts to ocean warming.

RevDate: 2019-09-21

Thomas-Vaslin V (2019)

Individuation and the Organization in Complex Living Ecosystem: Recursive Integration and Self-assertion by Holon-Lymphocytes.

Acta biotheoretica pii:10.1007/s10441-019-09364-w [Epub ahead of print].

Individuation and organization in complex living multi-level ecosystem occurs as dynamical processes from early ontogeny. The notion of living "holon" displaying dynamic self-assertion and integration is used here to explain the ecosystems dynamic processes. The update of the living holon state according to the continuous change of the dynamic system allows for its viability. This is interpreted as adaptation, selection and organization by the human that observes the system a posteriori from its level. Our model concerns the complex dynamics of the adaptive immune system, integrating holon-lymphocytes that collectively preserve the identity and integrity of the organism. Each lymphocyte individualizes as a dynamic holon-lymphocyte, with somatic gene individuation leading to an individual, singular antigen immunoreceptor type, promoting the self-assertion. In turn, the "Immunoception" allows for perception of the environmental antigenic context, thus integration of the holon in its environment. The self-assertion/integration of holon-lymphocyte starts from fetal stages and is influenced by mother Lamarckian acquired historicity transmissions, a requisite for the integrity of the holobiont-organism. We propose a dynamic model of the perception by holon-lymphocyte, and at the supra-clonal level of the immune system functions that sustain the identity and integrity of the holon-holobiont organism.

RevDate: 2019-09-18

García-López R, Pérez-Brocal V, A Moya (2019)

Beyond cells - The virome in the human holobiont.

Microbial cell (Graz, Austria), 6(9):373-396 pii:MIC0179E109.

Viromics, or viral metagenomics, is a relatively new and burgeoning field of research that studies the complete collection of viruses forming part of the microbiota in any given niche. It has strong foundations rooted in over a century of discoveries in the field of virology and recent advances in molecular biology and sequencing technologies. Historically, most studies have deconstructed the concept of viruses into a simplified perception of viral agents as mere pathogens, which demerits the scope of large-scale viromic analyses. Viruses are, in fact, much more than regular parasites. They are by far the most dynamic and abundant entity and the greatest killers on the planet, as well as the most effective geo-transforming genetic engineers and resource recyclers, acting on all life strata in any habitat. Yet, most of this uncanny viral world remains vastly unexplored to date, greatly hindered by the bewildering complexity inherent to such studies and the methodological and conceptual limitations. Viromic studies are just starting to address some of these issues but they still lag behind microbial metagenomics. In recent years, however, higher-throughput analysis and resequencing have rekindled interest in a field that is just starting to show its true potential. In this review, we take a look at the scientific and technological developments that led to the advent of viral and bacterial metagenomics with a particular, but not exclusive, focus on human viromics from an ecological perspective. We also address some of the most relevant challenges that current viral studies face and ponder on the future directions of the field.

RevDate: 2019-09-18

Porro B, Mallien C, Hume BCC, et al (2019)

The many faced symbiotic snakelocks anemone (Anemonia viridis, Anthozoa): host and symbiont genetic differentiation among colour morphs.

Heredity pii:10.1038/s41437-019-0266-3 [Epub ahead of print].

How can we explain morphological variations in a holobiont? The genetic determinism of phenotypes is not always obvious and could be circumstantial in complex organisms. In symbiotic cnidarians, it is known that morphology or colour can misrepresent a complex genetic and symbiotic diversity. Anemonia viridis is a symbiotic sea anemone from temperate seas. This species displays different colour morphs based on pigment content and lives in a wide geographical range. Here, we investigated whether colour morph differentiation correlated with host genetic diversity or associated symbiotic genetic diversity by using RAD sequencing and symbiotic dinoflagellate typing of 140 sea anemones from the English Channel and the Mediterranean Sea. We did not observe genetic differentiation among colour morphs of A. viridis at the animal host or symbiont level, rejecting the hypothesis that A. viridis colour morphs correspond to species level differences. Interestingly, we however identified at least four independent animal host genetic lineages in A. viridis that differed in their associated symbiont populations. In conclusion, although the functional role of the different morphotypes of A. viridis remains to be determined, our approach provides new insights on the existence of cryptic species within A. viridis.

RevDate: 2019-09-15

Rausch P, Rühlemann M, Hermes BM, et al (2019)

Comparative analysis of amplicon and metagenomic sequencing methods reveals key features in the evolution of animal metaorganisms.

Microbiome, 7(1):133 pii:10.1186/s40168-019-0743-1.

BACKGROUND: The interplay between hosts and their associated microbiome is now recognized as a fundamental basis of the ecology, evolution, and development of both players. These interdependencies inspired a new view of multicellular organisms as "metaorganisms." The goal of the Collaborative Research Center "Origin and Function of Metaorganisms" is to understand why and how microbial communities form long-term associations with hosts from diverse taxonomic groups, ranging from sponges to humans in addition to plants.

METHODS: In order to optimize the choice of analysis procedures, which may differ according to the host organism and question at hand, we systematically compared the two main technical approaches for profiling microbial communities, 16S rRNA gene amplicon and metagenomic shotgun sequencing across our panel of ten host taxa. This includes two commonly used 16S rRNA gene regions and two amplification procedures, thus totaling five different microbial profiles per host sample.

CONCLUSION: While 16S rRNA gene-based analyses are subject to much skepticism, we demonstrate that many aspects of bacterial community characterization are consistent across methods. The resulting insight facilitates the selection of appropriate methods across a wide range of host taxa. Overall, we recommend single- over multi-step amplification procedures, and although exceptions and trade-offs exist, the V3 V4 over the V1 V2 region of the 16S rRNA gene. Finally, by contrasting taxonomic and functional profiles and performing phylogenetic analysis, we provide important and novel insight into broad evolutionary patterns among metaorganisms, whereby the transition of animals from an aquatic to a terrestrial habitat marks a major event in the evolution of host-associated microbial composition.

RevDate: 2019-09-05

Li J, Wang T, Yu S, et al (2019)

Community characteristics and ecological roles of bacterial biofilms associated with various algal settlements on coastal reefs.

Journal of environmental management, 250:109459 pii:S0301-4797(19)31177-6 [Epub ahead of print].

Bacterial biofilms, which are a group of bacteria attaching to and ultimately forming communities on reefs, perform essential ecological functions in coastal ecosystems. Particularly, they may attract or repulse the settling down of opportunistic algae. However, this phenomenon and the interaction mechanism are not fully understood. This study investigated reefs from the Changdao coastal zone to determine the structures and functions of bacterial biofilms symbiosing with various algae using high-throughput sequencing analysis. The Shannon diversity index of microbiota with algal symbiosis reached 5.34, which was higher than that of microbiota wherein algae were absent (4.80). The beta diversity results for 11 samples revealed that there existed a separation between bacterial communities on reefs with and without attached algae, while communities with similar algae clustered together. The taxa mostly associated with algae-symbiotic microbiota are the Actinobacteria phylum, and the Flavobacteriia and Gammaproteobacteria classes. The Cyanobacteria phylum was not associated with algae-symbiotic microbiota. As revealed by functional analysis, the bacteria mostly involved in the metabolism of sulfur were represented by brown and red algae in the biofilm symbiosis. Bacteria related to the metabolism of certain trace elements were observed only in specific groups. Moreover, phototrophy-related bacteria were less abundant in samples coexisting with algae. This study established the link between bacterial biofilms and algal settlements on costal reefs, and revealed the possible holobiont relationship between them. This may provide new technical directions toward realizing algal cultivation and management during the construction of artificial reef ecosystems.

RevDate: 2019-09-05

Pupier CA, Bednarz VN, Grover R, et al (2019)

Divergent Capacity of Scleractinian and Soft Corals to Assimilate and Transfer Diazotrophically Derived Nitrogen to the Reef Environment.

Frontiers in microbiology, 10:1860.

Corals are associated with dinitrogen (N2)-fixing bacteria that potentially represent an additional nitrogen (N) source for the coral holobiont in oligotrophic reef environments. Nevertheless, the few studies investigating the assimilation of diazotrophically derived nitrogen (DDN) by tropical corals are limited to a single scleractinian species (i.e., Stylophora pistillata). The present study quantified DDN assimilation rates in four scleractinian and three soft coral species from the shallow waters of the oligotrophic Northern Red Sea using the 15N2 tracer technique. All scleractinian species significantly stimulated N2 fixation in the coral-surrounding seawater (and mucus) and assimilated DDN into their tissue. Interestingly, N2 fixation was not detected in the tissue and surrounding seawater of soft corals, despite the fact that soft corals were able to take up DDN from a culture of free-living diazotrophs. Soft coral mucus likely represents an unfavorable habitat for the colonization and activity of diazotrophs as it contains a low amount of particulate organic matter, with a relatively high N content, compared to the mucus of scleractinian corals. In addition, it is known to present antimicrobial properties. Overall, this study suggests that DDN assimilation into coral tissues depends on the presence of active diazotrophs in the coral's mucus layer and/or surrounding seawater. Since N is often a limiting nutrient for primary productivity in oligotrophic reef waters, the divergent capacity of scleractinian and soft corals to promote N2 fixation may have implications for N availability and reef biogeochemistry in scleractinian versus soft coral-dominated reefs.

RevDate: 2019-09-05

Gantt SE, McMurray SE, Stubler AD, et al (2019)

Testing the relationship between microbiome composition and flux of carbon and nutrients in Caribbean coral reef sponges.

Microbiome, 7(1):124 pii:10.1186/s40168-019-0739-x.

BACKGROUND: Sponges are important suspension-feeding members of reef communities, with the collective capacity to overturn the entire water column on shallow Caribbean reefs every day. The sponge-loop hypothesis suggests that sponges take up dissolved organic carbon (DOC) and, via assimilation and shedding of cells, return carbon to the reef ecosystem as particulate organic carbon (POC). Sponges host complex microbial communities within their tissues that may play a role in carbon and nutrient cycling within the sponge holobiont. To investigate this relationship, we paired microbial community characterization (16S rRNA analysis, Illumina Mi-Seq platform) with carbon (DOC, POC) and nutrient (PO4, NOx, NH4) flux data (specific filtration rate) for 10 common Caribbean sponge species at two distant sites (Florida Keys vs. Belize, ~ 1203 km apart).

RESULTS: Distance-based linear modeling revealed weak relationships overall between symbiont structure and carbon and nutrient flux, suggesting that the observed differences in POC, DOC, PO4, and NOx flux among sponges are not caused by variations in the composition of symbiont communities. In contrast, significant correlations between symbiont structure and NH4 flux occurred consistently across the dataset. Further, several individual symbiont taxa (OTUs) exhibited relative abundances that correlated with NH4 flux, including one OTU affiliated with the ammonia-oxidizing genus Cenarchaeum.

CONCLUSIONS: Combined, these results indicate that microbiome structure is uncoupled from sponge carbon cycling and does not explain variation in DOC uptake among Caribbean coral reef sponges. Accordingly, differential DOC assimilation by sponge cells or stable microbiome components may ultimately drive carbon flux in the sponge holobiont.

RevDate: 2019-08-19

Liu H, Macdonald CA, Cook J, et al (2019)

An Ecological Loop: Host Microbiomes across Multitrophic Interactions.

Trends in ecology & evolution pii:S0169-5347(19)30223-X [Epub ahead of print].

Our knowledge of host-associated microorganisms and their role in host functions is rapidly evolving. Stress-affected plants assemble beneficial microbes in their rhizosphere to maximize survival and growth. Similarly, insects have gut microbiomes that extend their functional repertoire in fighting stress. A strong microbial linkage between soil, plants, and pollinators is emerging and this can influence pollination services and overall ecosystem health. Yet, the nature of microbial interactions between different ecosystem components remains poorly understood. Here we highlight the acquisition pathways of beneficial microbes and their functions in protecting hosts against stress. By adopting a new 'eco-holobiont' approach, which explicitly incorporates biotic feedbacks, we can significantly expand our ecological understanding and better develop sustainable environmental management.

RevDate: 2019-08-18

Tourneroche A, Lami R, Hubas C, et al (2019)

Bacterial-Fungal Interactions in the Kelp Endomicrobiota Drive Autoinducer-2 Quorum Sensing.

Frontiers in microbiology, 10:1693.

Brown macroalgae are an essential component of temperate coastal ecosystems and a growing economic sector. They harbor diverse microbial communities that regulate algal development and health. This algal holobiont is dynamic and achieves equilibrium via a complex network of microbial and host interactions. We now report that bacterial and fungal endophytes associated with four brown algae (Ascophyllum nodosum, Pelvetia canaliculata, Laminaria digitata, and Saccharina latissima) produce metabolites that interfere with bacterial autoinducer-2 quorum sensing, a signaling system implicated in virulence and host colonization. Additionally, we performed co-culture experiments combined to a metabolomic approach and demonstrated that microbial interactions influence production of metabolites, including metabolites involved in quorum sensing. Collectively, the data highlight autoinducer-2 quorum sensing as a key metabolite in the complex network of interactions within the algal holobiont.

RevDate: 2019-08-25

Miller WB, Torday JS, F Baluška (2019)

The N-Space episenome unifies cellular information space-time within Cognition-Based Evolution.

Progress in biophysics and molecular biology pii:S0079-6107(19)30148-8 [Epub ahead of print].

Self-referential cellular homeostasis is maintained by the measured assessment of both internal status and external conditions based within an integrated cellular information field. This cellular field attachment to biologic information space-time coordinates environmental inputs by connecting the cellular senome, as the sum of the sensory experiences of the cell, with its genome and epigenome. In multicellular organisms, individual cellular information fields aggregate into a collective information architectural matrix, termed a N-space Episenome, that enables mutualized organism-wide information management. It is hypothesized that biological organization represents a dual heritable system constituted by both its biological materiality and a conjoining N-space Episenome. It is further proposed that morphogenesis derives from reciprocations between these inter-related facets to yield coordinated multicellular growth and development. The N-space Episenome is conceived as a whole cell informational projection that is heritable, transferable via cell division and essential for the synchronous integration of the diverse self-referential cells that constitute holobionts.

RevDate: 2019-08-30

Zhang S, Song W, Wemheuer B, et al (2019)

Comparative Genomics Reveals Ecological and Evolutionary Insights into Sponge-Associated Thaumarchaeota.

mSystems, 4(4): pii:4/4/e00288-19.

Thaumarchaeota are frequently reported to associate with marine sponges (phylum Porifera); however, little is known about the features that distinguish them from their free-living thaumarchaeal counterparts. In this study, thaumarchaeal metagenome-assembled genomes (MAGs) were reconstructed from metagenomic data sets derived from the marine sponges Hexadella detritifera, Hexadella cf. detritifera, and Stylissa flabelliformis Phylogenetic and taxonomic analyses revealed that the three thaumarchaeal MAGs represent two new species within the genus Nitrosopumilus and one novel genus, for which we propose the names "CandidatusUNitrosopumilus hexadellus," "CandidatusUNitrosopumilus detritiferus," and "CandidatusUCenporiarchaeum stylissum" (the U superscript indicates that the taxon is uncultured). Comparison of these genomes to data from the Sponge Earth Microbiome Project revealed that "CaUCenporiarchaeum stylissum" has been exclusively detected in sponges and can hence be classified as a specialist, while "CaUNitrosopumilus detritiferus" and "CaUNitrosopumilus hexadellus" are also detected outside the sponge holobiont and likely lead a generalist lifestyle. Comparison of the sponge-associated MAGs to genomes of free-living Thaumarchaeota revealed signatures that indicate functional features of a sponge-associated lifestyle, and these features were related to nutrient transport and metabolism, restriction-modification, defense mechanisms, and host interactions. Each species exhibited distinct functional traits, suggesting that they have reached different stages of evolutionary adaptation and/or occupy distinct ecological niches within their sponge hosts. Our study therefore offers new evolutionary and ecological insights into the symbiosis between sponges and their thaumarchaeal symbionts.IMPORTANCE Sponges represent ecologically important models to understand the evolution of symbiotic interactions of metazoans with microbial symbionts. Thaumarchaeota are commonly found in sponges, but their potential adaptations to a host-associated lifestyle are largely unknown. Here, we present three novel sponge-associated thaumarchaeal species and compare their genomic and predicted functional features with those of closely related free-living counterparts. We found different degrees of specialization of these thaumarchaeal species to the sponge environment that is reflected in their host distribution and their predicted molecular and metabolic properties. Our results indicate that Thaumarchaeota may have reached different stages of evolutionary adaptation in their symbiosis with sponges.

RevDate: 2019-08-14

Drago L, Panelli S, Bandi C, et al (2019)

What Pediatricians Should Know Before Studying Gut Microbiota.

Journal of clinical medicine, 8(8): pii:jcm8081206.

Billions of microorganisms, or "microbiota", inhabit the gut and affect its homeostasis, influencing, and sometimes causing if altered, a multitude of diseases. The genomes of the microbes that form the gut ecosystem should be summed to the human genome to form the hologenome due to their influence on human physiology; hence the term "microbiome" is commonly used to refer to the genetic make-up and gene-gene interactions of microbes. This review attempts to provide insight into this recently discovered vital organ of the human body, which has yet to be fully explored. We herein discuss the rhythm and shaping of the microbiome at birth and during the first years leading up to adolescence. Furthermore, important issues to consider for conducting a reliable microbiome study including study design, inclusion/exclusion criteria, sample collection, storage, and variability of different sampling methods as well as the basic terminology of molecular approaches, data analysis, and clinical interpretation of results are addressed. This basic knowledge aims to provide the pediatricians with a key tool to avoid data dispersion and pitfalls during child microbiota study.

RevDate: 2019-08-14

Dalit M, Keren ML, Eviatar W, et al (2019)

The Algal Symbiont Modifies the Transcriptome of the Scleractinian Coral Euphyllia paradivisa During Heat Stress.

Microorganisms, 7(8): pii:microorganisms7080256.

The profound mutualistic symbiosis between corals and their endosymbiotic counterparts, Symbiodiniaceae algae, has been threatened by the increase in seawater temperatures, leading to breakdown of the symbiotic relationship-coral bleaching. To characterize the heat-stress response of the holobiont, we generated vital apo-symbiotic Euphylliaparadivisa corals that lacked the endosymbiotic algae. Using RNA sequencing, we analyzed the gene expression of these apo-symbionts vs. symbiotic ones, to test the effect of the algal presence on the tolerance of the coral. We utilized literature-derived lists of "symbiosis differentially expressed genes" and "coral heat-stress genes" in order to compare between the treatments. The symbiotic and apo-symbiotic samples were segregated into two separate groups with several different enriched gene ontologies. Our findings suggest that the presence of endosymbionts has a greater negative impact on the host than the environmental temperature conditions experienced by the holobiont. The peak of the stress reaction was identified as 28 °C, with the highest number of differentially expressed genes. We suggest that the algal symbionts increase coral holobiont susceptibility to elevated temperatures. Currently, we can only speculate whether coral species, such as E.paradivisa, with the plasticity to also flourish as apo-symbionts, may have a greater chance to withstand the upcoming global climate change challenge.

RevDate: 2019-08-15

Abdelfattah A, Sanzani SM, Wisniewski M, et al (2019)

Revealing Cues for Fungal Interplay in the Plant-Air Interface in Vineyards.

Frontiers in plant science, 10:922.

Plant-associated microorganisms play a crucial role in plant health and productivity. Belowground microbial diversity is widely reported as a major factor in determining the composition of the plant microbiome. In contrast, much less is known about the role of the atmosphere in relation to the plant microbiome. The current study examined the hypothesis that the atmospheric microbiome influences the composition of fungal communities of the aboveground organs (flowers, fruit, and leaves) of table grape and vice versa. The atmosphere surrounding grape plantings exhibited a significantly higher level of fungal diversity relative to the nearby plant organs and shared a higher number of phylotypes (5,536 OTUs, 40.3%) with the plant than between organs of the same plant. Using a Bayesian source tracking approach, plant organs were determined to be the major source of the atmospheric fungal community (92%). In contrast, airborne microbiota had only a minor contribution to the grape microbiome, representing the source of 15, 4, and 35% of the fungal communities of leaves, flowers, and fruits, respectively. Moreover, data indicate that plant organs and the surrounding atmosphere shared a fraction of each other's fungal communities, and this shared pool of fungal taxa serves as a two-way reservoir of microorganisms. Microbial association analysis highlighted more positive than negative interactions between fungal phylotypes. Positive interactions were more common within the same environment, while negative interactions appeared to occur more frequently between different environments, i.e., atmosphere, leaf, flower, and fruit. The current study revealed the interplay between the fungal communities of the grape phyllosphere with the surrounding air. Plants were identified as a major source of recruitment for the atmospheric microbiome, while the surrounding atmosphere contributed only a small fraction of the plant fungal community. The results of the study suggested that the plant-air interface modulates the plant recruitment of atmospheric fungi, taking a step forward in understanding the plant holobiont assembly and how the atmosphere surrounding plants plays a role in this process. The impact of plants on the atmospheric microbiota has several biological and epidemiological implications for plants and humans.

RevDate: 2019-08-11

Damjanovic K, van Oppen MJH, Menéndez P, et al (2019)

Experimental Inoculation of Coral Recruits With Marine Bacteria Indicates Scope for Microbiome Manipulation in Acropora tenuis and Platygyra daedalea.

Frontiers in microbiology, 10:1702.

Coral-associated microorganisms are essential for maintaining the health of the coral holobiont by participating in nutrient cycling and protecting the coral host from pathogens. Under stressful conditions, disruption of the coral prokaryotic microbiome is linked to increased susceptibility to diseases and mortality. Inoculation of corals with beneficial microbes could confer enhanced stress tolerance to the host and may be a powerful tool to help corals thrive under challenging environmental conditions. Here, we explored the feasibility of coral early life stage microbiome manipulation by repeatedly inoculating coral recruits with a bacterial cocktail generated in the laboratory. Co-culturing the two species Acropora tenuis and Platygyra daedalea allowed us to simultaneously investigate the effect of host factors on the coral microbiome. Inoculation cocktails were regularly prepared from freshly grown pure bacterial cultures, which were hence assumed viable, and characterized via the optical density measurement of each individual strain put in suspension. Coral early recruits were inoculated seven times over 3 weeks and sampled once 36 h following the last inoculation event. At this time point, the cumulative inoculations with the bacterial cocktails had a strong effect on the bacterial community composition in recruits of both coral species. While the location of bacterial cells within the coral hosts was not assessed, metabarcoding using the 16S rRNA gene revealed that two and six of the seven bacterial strains administered through the cocktails were significantly enriched in inoculated recruits of A. tenuis and P. daedalea, respectively, compared to control recruits. Despite being reared in the same environment, A. tenuis and P. daedalea established significantly different bacterial communities, both in terms of taxonomic composition and diversity measurements. These findings indicate that coral host factors as well as the environmental bacterial pool play a role in shaping coral-associated bacterial community composition. Host factors may include microbe transmission mode (horizontal versus maternal) and host specificity. While the long-term stability of taxa included in the bacterial inocula as members of the host-associated microbiome remains to be evaluated, our results provide support for the feasibility of coral microbiome manipulation, at least in a laboratory setting.

RevDate: 2019-08-05

Rouzé R, Moné A, Delbac F, et al (2019)

The Honeybee Gut Microbiota Is Altered after Chronic Exposure to Different Families of Insecticides and Infection by Nosema ceranae.

Microbes and environments [Epub ahead of print].

The gut of the European honeybee Apis mellifera is the site of exposure to multiple stressors, such as pathogens and ingested chemicals. Therefore, the gut microbiota, which contributes to host homeostasis, may be altered by these stressors. The abundance of major bacterial taxa in the gut was evaluated in response to infection with the intestinal parasite Nosema ceranae or chronic exposure to low doses of the neurotoxic insecticides coumaphos, fipronil, thiamethoxam, and imidacloprid. Experiments were performed under laboratory conditions on adult workers collected from hives in February (winter bees) and July (summer bees) and revealed season-dependent changes in the bacterial community composition. N. ceranae and a lethal fipronil treatment increased the relative abundance of both Gilliamella apicola and Snodgrassella alvi in surviving winter honeybees. The parasite and a sublethal exposure to all insecticides decreased the abundance of Bifidobacterium spp. and Lactobacillus spp. regardless of the season. The similar effects induced by insecticides belonging to distinct molecular families suggested a shared and indirect mode of action on the gut microbiota, possibly through aspecific alterations in gut homeostasis. These results demonstrate that infection and chronic exposure to low concentrations of insecticides may affect the honeybee holobiont.

RevDate: 2019-08-02

Geva-Zatorsky N, Elinav E, S Pettersson (2019)

When Cultures Meet: The Landscape of "Social" Interactions between the Host and Its Indigenous Microbes.

BioEssays : news and reviews in molecular, cellular and developmental biology [Epub ahead of print].

Animals exist as biodiverse composite organisms that include microbial residents, eukaryotic cells, and organs that collectively form a human being. Through an interdependent relationship and an inherent ability to transmit and reciprocate stimuli in a bidirectional way, a human body or the holobiont secures growth, health, and reproduction. As such, the survival of a holobiont is dependent on the maintenance of biological order including metabolic homeostasis by tight regulation of the communication between its eukaryotic and prokaryotic residents. In this review an overview and perspective are provided on the bidirectional communication between microbes and their host in mutually nurturing biochemical, biological, and social interconnected relationships between the components of the holobiont. An emphasis is placed on exemplifying microbiome-mediated effects on host functions-aiming to integrate microbiome functionality to host physiology, be it health or disease. Nutrition, immunology, and sexual dimorphism have been traversed extensively to reflect on health and mind states, social interactions, and urbanization defects/effects. Finally, examples of molecular mechanisms potentially orchestrating these complex transkingdom interactions are provided.

RevDate: 2019-07-30

Carrasco J, GM Preston (2019)

Growing edible mushrooms: a conversation between bacteria and fungi.

Environmental microbiology [Epub ahead of print].

Mushroom cropping consists of the development and fructification of different fungal species in soil or selective substrates that provide nutrients and support for the crop. The microorganisms present in these environments strongly influence, and in some cases are required for the growth and fructification of cultivated mushrooms. Some fungi such as truffles and morels form ectomycorrhizal associations with host plants. For these fungi helper bacteria play an important role in the establishment of plant-fungal symbioses. Selective processes acting on the microbiota present in substrates and soils determine the composition of the microbiota inhabiting the fruit bodies or interacting with fungal hyphae, and both configure the mushroom holobiont, understood as the fungus plus associated microorganisms. Here we review current knowledge regarding the cross talk between bacteria and fungi during mushroom cultivation. We highlight the potential use of bioinoculants as agronomical amendments to increase mushroom productivity through growth promotion, or as biocontrol agents to control pests and diseases. This article is protected by copyright. All rights reserved.

RevDate: 2019-07-28

Taffner J, Cernava T, Erlacher A, et al (2019)

Novel insights into plant-associated archaea and their functioning in arugula (Eruca sativa Mill.).

Journal of advanced research, 19:39-48 pii:S2090-1232(19)30086-4.

A plant's microbiota has various implications for the plant's health and performance; however, the roles of many microbial lineages, particularly Archaea, have not been explored in detail. In the present study, analysis of archaea-specific 16S rRNA gene fragments and shotgun-sequenced metagenomes was combined with visualization techniques to obtain the first insights into the archaeome of a common salad plant, arugula (Eruca sativa Mill.). The archaeal communities associated with the soil, rhizosphere and phyllosphere were distinct, but a high proportion of community members were shared among all analysed habitats. Soil habitats exhibited the highest diversity of Archaea, followed by the rhizosphere and the phyllosphere. The archaeal community was dominated by Thaumarchaeota and Euryarchaeota, with the most abundant taxa assigned to Candidatus Nitrosocosmicus, species of the 'Soil Crenarchaeotic Group' and, interestingly, Methanosarcina. Moreover, a large number of archaea-assigned sequences remained unassigned at lower taxonomic levels. Overall, analysis of shotgun-sequenced total-community DNA revealed a more diverse archaeome. Differences were evident at the class level and at higher taxonomic resolutions when compared to results from the 16S rRNA gene fragment amplicon library. Functional assessments primarily revealed archaeal genes related to response to stress (especially oxidative stress), CO2 fixation, and glycogen degradation. Microscopic visualizations of fluorescently labelled archaea in the phyllosphere revealed small scattered colonies, while archaea in the rhizosphere were found to be embedded within large bacterial biofilms. Altogether, Archaea were identified as a rather small but niche-specific component of the microbiomes of the widespread leafy green plant arugula.

RevDate: 2019-07-28

Hartmann A, Fischer D, Kinzel L, et al (2019)

Assessment of the structural and functional diversities of plant microbiota: Achievements and challenges - A review.

Journal of advanced research, 19:3-13 pii:S2090-1232(19)30085-2.

Analyses of the spatial localization and the functions of bacteria in host plant habitats through in situ identification by immunological and molecular genetic techniques combined with high resolving microscopic tools and 3D-image analysis contributed substantially to a better understanding of the functional interplay of the microbiota in plants. Among the molecular genetic methods, 16S-rRNA genes were of central importance to reconstruct the phylogeny of newly isolated bacteria and to localize them in situ. However, they usually do not allow resolution for phylogenetic affiliations below genus level. Especially, the separation of opportunistic human pathogens from plant beneficial strains, currently allocated to the same species, needs genome-based resolving techniques. Whole bacterial genome sequences allow to discriminate phylogenetically closely related strains. In addition, complete genome sequences enable strain-specific monitoring for biotechnologically relevant strains. In this mini-review we present high resolving approaches for analysis of the composition and key functions of plant microbiota, focusing on interactions of diazotrophic plant growth promoting bacteria, like Azospirillum brasilense, with non-legume host plants. Combining high resolving microscopic analyses with specific immunological detection methods and molecular genetic tools, including especially transcriptome analyses of both the bacterial and plant partners, enables new insights into key traits of beneficial bacteria-plant interactions in holobiontic systems.

RevDate: 2019-07-23

Gilbert SF (2019)

Developmental symbiosis facilitates the multiple origins of herbivory.

Evolution & development [Epub ahead of print].

Developmental bias toward particular evolutionary trajectories can be facilitated through symbiosis. Organisms are holobionts, consisting of zygote-derived cells and a consortia of microbes, and the development, physiology, and immunity of animals are properties of complex interactions between the zygote-derived cells and microbial symbionts. Such symbionts can be agents of developmental plasticity, allowing an organism to develop in particular directions. This plasticity can lead to genetic assimilation either through the incorporation of microbial genes into host genomes or through the direct maternal transmission of the microbes. Such plasticity can lead to niche construction, enabling the microbes to remodel host anatomy and/or physiology. In this article, I will focus on the ability of symbionts to bias development toward the evolution of herbivory. I will posit that the behavioral and morphological manifestations of herbivorous phenotypes must be preceded by the successful establishment of a community of symbiotic microbes that can digest cell walls and detoxify plant poisons. The ability of holobionts to digest plant materials can range from being a plastic trait, dependent on the transient incorporation of environmental microbes, to becoming a heritable trait of the holobiont organism, transmitted through the maternal propagation of symbionts or their genes.

RevDate: 2019-08-25

Díaz-Sánchez S, Estrada-Peña A, Cabezas-Cruz A, et al (2019)

Evolutionary Insights into the Tick Hologenome.

Trends in parasitology, 35(9):725-737.

Recently, our knowledge of the composition and complexity of tick microbial communities has increased and supports microbial impact on tick biology. Results support a phylogenetic association between ticks and their microbiota across evolution; this is known as phylosymbiosis. Herein, using published datasets, we confirm the existence of phylosymbiosis between Ixodes ticks and their microbial communities. The strong phylosymbiotic signal and the phylogenetic structure of microbial communities associated with Ixodid ticks revealed that phylosymbiosis may be a widespread phenomenon in tick-microbiota evolution. This finding supports the existence of a species-specific tick hologenome with a largely unexplored influence on tick biology and pathogen transmission. These results may provide potential targets for the construction of paratransgenic ticks to control tick infestations and tick-borne diseases.

RevDate: 2019-08-10

Chan WY, Peplow LM, Menéndez P, et al (2019)

The roles of age, parentage and environment on bacterial and algal endosymbiont communities in Acropora corals.

Molecular ecology [Epub ahead of print].

The bacterial and microalgal endosymbiont (Symbiodiniaceae spp.) communities associated with corals have important roles in their health and resilience, yet little is known about the factors driving their succession during early coral life stages. Using 16S rRNA gene and ITS2 metabarcoding, we compared these communities in four Acropora coral species and their hybrids obtained from two laboratory crosses (Acropora tenuis × Acropora loripes and Acropora sarmentosa × Acropora florida) across the parental, recruit (7 months old) and juvenile (2 years old) life stages. We tested whether microbiomes differed between (a) life stages, (b) hybrids and purebreds, and (c) treatment conditions (ambient/elevated temperature and pCO2). Microbial communities of early life stage corals were highly diverse, lacked host specificity and were primarily determined by treatment conditions. Over time, a winnowing process occurred, and distinct microbial communities developed between the two species pair crosses by 2 years of age, irrespective of hybrid or purebred status. These findings suggest that the microbial communities of corals have a period of flexibility prior to adulthood, which can be valuable to future research aimed at the manipulation of coral microbial communities.

RevDate: 2019-08-10

Perez-Lamarque B, H Morlon (2019)

Characterizing symbiont inheritance during host-microbiota evolution: Application to the great apes gut microbiota.

Molecular ecology resources [Epub ahead of print].

Microbiota play a central role in the functioning of multicellular life, yet understanding their inheritance during host evolutionary history remains an important challenge. Symbiotic microorganisms are either acquired from the environment during the life of the host (i.e. environmental acquisition), transmitted across generations with a faithful association with their hosts (i.e. strict vertical transmission), or transmitted with occasional host switches (i.e. vertical transmission with horizontal switches). These different modes of inheritance affect microbes' diversification, which at the two extremes can be independent from that of their associated host or follow host diversification. The few existing quantitative tools for investigating the inheritance of symbiotic organisms rely on cophylogenetic approaches, which require knowledge of both host and symbiont phylogenies, and are therefore often not well adapted to DNA metabarcoding microbial data. Here, we develop a model-based framework for identifying vertically transmitted microbial taxa. We consider a model for the evolution of microbial sequences on a fixed host phylogeny that includes vertical transmission and horizontal host switches. This model allows estimating the number of host switches and testing for strict vertical transmission and independent evolution. We test our approach using simulations. Finally, we illustrate our framework on gut microbiota high-throughput sequencing data of the family Hominidae and identify several microbial taxonomic units, including fibrolytic bacteria involved in carbohydrate digestion, that tend to be vertically transmitted.

RevDate: 2019-08-19

Rosenberg E, I Zilber-Rosenberg (2019)

The hologenome concept of evolution: do mothers matter most?.

BJOG : an international journal of obstetrics and gynaecology [Epub ahead of print].

The hologenome concept of evolution is discussed, with special emphasis placed upon the microbiome of women. The microbiome is dynamic, changing under different conditions, and differs between women and men. Genetic variation occurs not only in the host, but also in the microbiome by the acquisition of novel microbes, the amplification of specific microbes, and horizontal gene transfer. The majority of unique genes in human holobionts are found in microbiomes, and mothers are responsible for transferring most of these to their offspring during birth, breastfeeding, and physical contact. Thus, mothers are likely to be the primary providers of the majority of genetic information to offspring via mitochondria and the microbiome. TWEETABLE ABSTRACT: Microbiomes differ between women and men. Most genes in humans are in the microbiome. Mothers transfer most of these genes to offspring.

RevDate: 2019-07-17

Shih JL, Selph KE, Wall CB, et al (2019)

Trophic Ecology of the Tropical Pacific Sponge Mycale grandis Inferred from Amino Acid Compound-Specific Isotopic Analyses.

Microbial ecology pii:10.1007/s00248-019-01410-x [Epub ahead of print].

Many sponges host abundant and active microbial communities that may play a role in the uptake of dissolved organic matter (DOM) by the sponge holobiont, although the mechanism of DOM uptake and metabolism is uncertain. Bulk and compound-specific isotopic analysis of whole sponge, isolated sponge cells, and isolated symbiotic microbial cells of the shallow water tropical Pacific sponge Mycale grandis were used to elucidate the trophic relationships between the host sponge and its associated microbial community. δ15N and δ13C values of amino acids in M. grandis isolated sponge cells are not different from those of its bacterial symbionts. Consequently, there is no difference in trophic position of the sponge and its symbiotic microbes indicating that M. grandis sponge cell isolates do not display amino acid isotopic characteristics typical of metazoan feeding. Furthermore, both the isolated microbial and sponge cell fractions were characterized by a similarly high ΣV value-a measure of bacterial-re-synthesis of organic matter calculated from the sum of variance among individual δ15N values of trophic amino acids. These high ΣV values observed in the sponge suggest that M. grandis is not reliant on translocated photosynthate from photosymbionts or feeding on water column picoplankton, but obtains nutrition through the uptake of amino acids of bacterial origin. Our results suggest that direct assimilation of bacterially synthesized amino acids from its symbionts, either in a manner similar to translocation observed in the coral holobiont or through phagotrophic feeding, is an important if not primary pathway of amino acid acquisition for M. grandis.

RevDate: 2019-07-19

Pollock FJ, Lamb JB, van de Water JAJM, et al (2019)

Reduced diversity and stability of coral-associated bacterial communities and suppressed immune function precedes disease onset in corals.

Royal Society open science, 6(6):190355 pii:rsos190355.

Disease is an emerging threat to coral reef ecosystems worldwide, highlighting the need to understand how environmental conditions interact with coral immune function and associated microbial communities to affect holobiont health. Increased coral disease incidence on reefs adjacent to permanently moored platforms on Australia's Great Barrier Reef provided a unique case study to investigate environment-host-microbe interactions in situ. Here, we evaluate coral-associated bacterial community (16S rRNA amplicon sequencing), immune function (protein-based prophenoloxidase-activating system), and water quality parameters before, during and after a disease event. Over the course of the study, 31% of tagged colonies adjacent to platforms developed signs of white syndrome (WS), while all control colonies on a platform-free reef remained visually healthy. Corals adjacent to platforms experienced significant reductions in coral immune function. Additionally, the corals at platform sites that remained visually healthy throughout the study had reduced bacterial diversity compared to healthy colonies at the platform-free site. Interestingly, prior to the observation of macroscopic disease, corals that would develop WS had reduced bacterial diversity and significantly greater community heterogeneity between colonies compared to healthy corals at the same location. These results suggest that activities associated with offshore marine infrastructure impacts coral immunocompetence and associated bacterial community, which affects the susceptibility of corals to disease.

RevDate: 2019-07-31

McIlroy SE, Thompson PD, Yuan FL, et al (2019)

Subtropical thermal variation supports persistence of corals but limits productivity of coral reefs.

Proceedings. Biological sciences, 286(1907):20190882.

Concomitant to the decline of tropical corals caused by increasing global sea temperatures is the potential removal of barriers to species range expansions into subtropical and temperate habitats. In these habitats, species must tolerate lower annual mean temperature, wider annual temperature ranges and lower minimum temperatures. To understand ecophysiological traits that will impact geographical range boundaries, we monitored populations of five coral species within a marginal habitat and used a year of in situ measures to model thermal performance of vital host, symbiont and holobiont physiology. Metabolic responses to temperature revealed two acclimatization strategies: peak productivity occurring at annual midpoint temperatures (4-6°C lower than tropical counterparts), or at annual maxima. Modelled relationships between temperature and P:R were compared to a year of daily subtropical sea temperatures and revealed that the relatively short time spent at any one temperature, limited optimal performance of all strategies to approximately half the days of the year. Thus, while subtropical corals can adjust their physiology to persist through seasonal lows, seasonal variation seems to be the key factor limiting coral productivity. This constraint on rapid reef accretion within subtropical environments provides insight into the global distribution of future coral reefs and their ecosystem services.

RevDate: 2019-08-10

Wright RM, Mera H, Kenkel CD, et al (2019)

Positive genetic associations among fitness traits support evolvability of a reef-building coral under multiple stressors.

Global change biology [Epub ahead of print].

Climate change threatens organisms in a variety of interactive ways that requires simultaneous adaptation of multiple traits. Predicting evolutionary responses requires an understanding of the potential for interactions among stressors and the genetic variance and covariance among fitness-related traits that may reinforce or constrain an adaptive response. Here we investigate the capacity of Acropora millepora, a reef-building coral, to adapt to multiple environmental stressors: rising sea surface temperature, ocean acidification, and increased prevalence of infectious diseases. We measured growth rates (weight gain), coral color (a proxy for Symbiodiniaceae density), and survival, in addition to nine physiological indicators of coral and algal health in 40 coral genets exposed to each of these three stressors singly and combined. Individual stressors resulted in predicted responses (e.g., corals developed lesions after bacterial challenge and bleached under thermal stress). However, corals did not suffer substantially more when all three stressors were combined. Nor were trade-offs observed between tolerances to different stressors; instead, individuals performing well under one stressor also tended to perform well under every other stressor. An analysis of genetic correlations between traits revealed positive covariances, suggesting that selection to multiple stressors will reinforce rather than constrain the simultaneous evolution of traits related to holobiont health (e.g., weight gain and algal density). These findings support the potential for rapid coral adaptation under climate change and emphasize the importance of accounting for corals' adaptive capacity when predicting the future of coral reefs.

RevDate: 2019-07-16

Ziegler M, Grupstra CGB, Barreto MM, et al (2019)

Coral bacterial community structure responds to environmental change in a host-specific manner.

Nature communications, 10(1):3092 pii:10.1038/s41467-019-10969-5.

The global decline of coral reefs heightens the need to understand how corals respond to changing environmental conditions. Corals are metaorganisms, so-called holobionts, and restructuring of the associated bacterial community has been suggested as a means of holobiont adaptation. However, the potential for restructuring of bacterial communities across coral species in different environments has not been systematically investigated. Here we show that bacterial community structure responds in a coral host-specific manner upon cross-transplantation between reef sites with differing levels of anthropogenic impact. The coral Acropora hemprichii harbors a highly flexible microbiome that differs between each level of anthropogenic impact to which the corals had been transplanted. In contrast, the microbiome of the coral Pocillopora verrucosa remains remarkably stable. Interestingly, upon cross-transplantation to unaffected sites, we find that microbiomes become indistinguishable from back-transplanted controls, suggesting the ability of microbiomes to recover. It remains unclear whether differences to associate with bacteria flexibly reflects different holobiont adaptation mechanisms to respond to environmental change.

RevDate: 2019-07-10

Uroz S, Courty PE, P Oger (2019)

Plant Symbionts Are Engineers of the Plant-Associated Microbiome.

Trends in plant science pii:S1360-1385(19)30155-4 [Epub ahead of print].

Plants interact throughout their lives with environmental microorganisms. These interactions determine plant development, nutrition, and fitness in a dynamic and stressful environment, forming the basis for the holobiont concept in which plants and plant-associated microbes are not considered as independent entities but as a single evolutionary unit. A primary open question concerns whether holobiont structure is shaped by its microbial members or solely by the plant. Current knowledge of plant-microbe interactions argues that the establishment of symbiosis directly and indirectly conditions the plant-associated microbiome. We propose to define the impact of the symbiont on the plant microbiome as the 'symbiosis cascade effect', in which the symbionts and their plant host jointly shape the plant microbiome.

RevDate: 2019-07-30

Björk JR, Díez-Vives C, Astudillo-García C, et al (2019)

Vertical transmission of sponge microbiota is inconsistent and unfaithful.

Nature ecology & evolution, 3(8):1172-1183.

Co-evolutionary theory predicts that if beneficial microbial symbionts improve host fitness, they should be faithfully transmitted to offspring. More recently, the hologenome theory of evolution predicts resemblance between parent and offspring microbiomes and high partner fidelity between host species and their vertically transmitted microbes. Here, we test these ideas in multiple coexisting host species with highly diverse microbiota, leveraging known parent-offspring pairs sampled from eight species of wild marine sponges (Porifera). We found that the processes governing vertical transmission were both neutral and selective. A neutral model was a better fit to larval (R2 = 0.66) than to the adult microbiota (R2 = 0.27), suggesting that the importance of non-neutral processes increases as the sponge host matures. Microbes that are enriched above neutral expectations in adults were disproportionately transferred to offspring. Patterns of vertical transmission were, however, incomplete: larval sponges shared, on average, 44.8% of microbes with their parents, which was not higher than the fraction they shared with nearby non-parental adults. Vertical transmission was also inconsistent across siblings, as larval sponges from the same parent shared only 17% of microbes. Finally, we found no evidence that vertically transmitted microbes are faithful to a single sponge host species. Surprisingly, larvae were as likely to share vertically transmitted microbes with larvae from other sponge species as they were with their own species. Our study demonstrates that common predictions of vertical transmission that stem from species-poor systems are not necessarily true when scaling up to diverse and complex microbiomes.

RevDate: 2019-07-09

Jurriaans S, MO Hoogenboom (2019)

Thermal performance of scleractinian corals along a latitudinal gradient on the Great Barrier Reef.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 374(1778):20180546.

Species have evolved different mechanisms to cope with spatial and temporal temperature variability. Species with broad geographical distributions may be thermal generalists that perform well across a broad range of temperatures, or they might contain subpopulations of locally adapted thermal specialists. We quantified the variation in thermal performance of two coral species, Porites cylindrica and Acropora spp., along a latitudinal gradient over which temperature varies by approximately 6°C. Photosynthesis rates, respiration rates, maximum quantum yield and maximum electron transport rates were measured on coral fragments exposed to an acute temperature increase and decrease up to 5°C above and below the local average temperature. Results showed geographical variation in the performance curves of both species at holobiont and symbiont level, but this did not lead to an alignment of the optimal temperature for performance with the average temperature of the local environment, suggesting suboptimal coral performance of these coral populations in summer. Furthermore, symbiont thermal performance generally had an optimum closer to the average environmental temperature than holobiont performance, suggesting that symbionts have a higher capacity for acclimatization than the coral host, and can aid the coral host when temperatures are unfavourable. This article is part of the theme issue 'Physiological diversity, biodiversity patterns and global climate change: testing key hypotheses involving temperature and oxygen'.

RevDate: 2019-06-13

Lee SJ, Morse D, M Hijri (2019)

Holobiont chronobiology: mycorrhiza may be a key to linking aboveground and underground rhythms.

Mycorrhiza pii:10.1007/s00572-019-00903-4 [Epub ahead of print].

Circadian clocks are nearly ubiquitous timing mechanisms that can orchestrate rhythmic behavior and gene expression in a wide range of organisms. Clock mechanisms are becoming well understood in fungal, animal, and plant model systems, yet many of these organisms are surrounded by a complex and diverse microbiota which should be taken into account when examining their biology. Of particular interest are the symbiotic relationships between organisms that have coevolved over time, forming a unit called a holobiont. Several studies have now shown linkages between the circadian rhythms of symbiotic partners. Interrelated regulation of holobiont circadian rhythms seems thus important to coordinate shifts in activity over the day for all the partners. Therefore, we suggest that the classical view of "chronobiological individuals" should include "a holobiont" rather than an organism. Unfortunately, mechanisms that may regulate interspecies temporal acclimation and the evolution of the circadian clock in holobionts are far from being understood. For the plant holobiont, our understanding is particularly limited. In this case, the holobiont encompasses two different ecosystems, one above and the other below the ground, with the two potentially receiving timing information from different synchronizing signals (Zeitgebers). The arbuscular mycorrhizal (AM) symbiosis, formed by plant roots and fungi, is one of the oldest and most widespread associations between organisms. By mediating the nutritional flux between the plant and the many microbes in the soil, AM symbiosis constitutes the backbone of the plant holobiont. Even though the importance of the AM symbiosis has been well recognized in agricultural and environmental sciences, its circadian chronobiology remains almost completely unknown. We have begun to study the circadian clock of arbuscular mycorrhizal fungi, and we compile and here discuss the available information on the subject. We propose that analyzing the interrelated temporal organization of the AM symbiosis and determining its underlying mechanisms will advance our understanding of the role and coordination of circadian clocks in holobionts in general.

RevDate: 2019-06-19

Feng G, Zhang F, Banakar S, et al (2019)

Analysis of functional gene transcripts suggests active CO2 assimilation and CO oxidation by diverse bacteria in marine sponges.

FEMS microbiology ecology, 95(7):.

Bacteria are the dominant symbionts in sponges and are regarded as important contributors to ocean nutrient cycling; however, their roles in carbon utilization in sponge holobionts are seldom identified. Here, the in situ active bacteria and their CO2 assimilation and CO oxidation functions in sponges Theonella swinhoei, Plakortis simplex and Phakellia fusca were evaluated using the analysis of functional gene transcripts. Phylogenetically diverse bacteria belonging to 16 phyla were detected by 16S rRNA analysis. Particularly, some of the active bacteria appeared to be sponge-specific or even sponge species-specific. Transcribed autotrophic CO2 assimilation genes rbcL and rbcM, anaplerotic CO2 assimilation gene accC and aerobic CO oxidation gene coxL were uncovered and assigned to a wide variety of bacterial lineages. Some of these carbon metabolism genes showed specificity to sponge species or different transcriptional activity among the sponge species. This study uncovered the phylogenetic diversity of transcriptionally active bacteria especially with CO2 assimilation or CO oxidation functions, providing insights into the ecological functions of the sponge-symbiotic bacteria regarding carbon metabolism.

RevDate: 2019-06-14

Kellogg CA (2019)

Microbiomes of stony and soft deep-sea corals share rare core bacteria.

Microbiome, 7(1):90 pii:10.1186/s40168-019-0697-3.

BACKGROUND: Numerous studies have shown that bacteria form stable associations with host corals and have focused on identifying conserved "core microbiomes" of bacterial associates inferred to be serving key roles in the coral holobiont. Because studies tend to focus on only stony corals (order Scleractinia) or soft corals (order Alcyonacea), it is currently unknown if there are conserved bacteria that are shared by both. A meta-analysis was done of 16S rRNA amplicon data from multiple studies generated via identical methodology to allow direct comparisons of bacterial associates across seven deep-sea corals, including both stony and soft species: Anthothela grandiflora, Anthothela sp., Lateothela grandiflora, Lophelia pertusa, Paramuricea placomus, Primnoa pacifica, and Primnoa resedaeformis.

RESULTS: Twenty-three operational taxonomic units (OTUs) were consistently present in greater than 50% of the coral samples. Seven amplicon sequence variants (ASVs), five of which corresponded to a conserved OTU, were consistently present in greater than 30% of the coral samples including five or greater coral species. A majority of the conserved sequences had close matches with previously identified coral-associated bacteria. While known to dominate tropical and temperate coral microbiomes, Endozoicomonas were extremely rare or absent from these deep-sea corals. An Endozoicomonas OTU associated with Lo. pertusa in this study was most similar to those from shallow-water stony corals, while an OTU associated with Anthothela spp. was most similar to those from shallow-water gorgonians.

CONCLUSIONS: Bacterial sequences have been identified that are conserved at the level of class Anthozoa (i.e., found in both stony and soft corals, shallow and deep). These bacterial associates are therefore hypothesized to play important symbiotic roles and are highlighted for targeted future study. These conserved bacterial associates include taxa with the potential for nitrogen and sulfur cycling, detoxification, and hydrocarbon degradation. There is also some overlap with kit contaminants that need to be resolved. Rarely detected Endozoicomonas sequences are partitioned by whether the host is a stony coral or a soft coral, and the finer clustering pattern reflects the hosts' phylogeny.

RevDate: 2019-06-27

Thapa S, Li H, OHair J, et al (2019)

Biochemical Characteristics of Microbial Enzymes and Their Significance from Industrial Perspectives.

Molecular biotechnology, 61(8):579-601.

Microbes are ubiquitously distributed in nature and are a critical part of the holobiont fitness. They are perceived as the most potential biochemical reservoir of inordinately diverse and multi-functional enzymes. The robust nature of the microbial enzymes with thermostability, pH stability and multi-functionality make them potential candidates for the efficient biotechnological processes under diverse physio-chemical conditions. The need for sustainable solutions to various environmental challenges has further surged the demand for industrial enzymes. Fueled by the recent advent of recombinant DNA technology, genetic engineering, and high-throughput sequencing and omics techniques, numerous microbial enzymes have been developed and further exploited for various industrial and therapeutic applications. Most of the hydrolytic enzymes (protease being the dominant hydrolytic enzyme) have broad range of industrial uses such as food and feed processing, polymer synthesis, production of pharmaceuticals, manufactures of detergents, paper and textiles, and bio-fuel refinery. In this review article, after a short overview of microbial enzymes, an approach has been made to highlight and discuss their potential relevance in biotechnological applications and industrial bio-processes, significant biochemical characteristics of the microbial enzymes, and various tools that are revitalizing the novel enzymes discovery.

RevDate: 2019-06-03

Finlay BB, Pettersson S, Melby MK, et al (2019)

The Microbiome Mediates Environmental Effects on Aging.

BioEssays : news and reviews in molecular, cellular and developmental biology [Epub ahead of print].

Humans' indigenous microbes strongly influence organ functions in an age- and diet-dependent manner, adding an important dimension to aging biology that remains poorly understood. Although age-related differences in the gut microbiota composition correlate with age-related loss of organ function and diseases, including inflammation and frailty, variation exists among the elderly, especially centenarians and people living in areas of extreme longevity. Studies using short-lived as well as nonsenescent model organisms provide surprising functional insights into factors affecting aging and implicate attenuating effects of microbes as well as a crucial role for certain transcription factors like forkhead box O. The unexpected beneficial effects of microbes on aged animals imply an even more complex interplay between the gut microbiome and the host. The microbiome constitutes the major interface between humans and the environment, is influenced by biosocial stressors and behaviors, and mediates effects on health and aging processes, while being moderated by sex and developmental stages.

RevDate: 2019-06-10

Ahmed HI, Herrera M, Liew YJ, et al (2019)

Long-Term Temperature Stress in the Coral Model Aiptasia Supports the "Anna Karenina Principle" for Bacterial Microbiomes.

Frontiers in microbiology, 10:975.

The understanding of host-microbial partnerships has become a hot topic during the last decade as it has been shown that associated microbiota play critical roles in the host physiological functions and susceptibility to diseases. Moreover, the microbiome may contribute to host resilience to environmental stressors. The sea anemone Aiptasia is a good laboratory model system to study corals and their microbial symbiosis. In this regard, studying its bacterial microbiota provides a better understanding of cnidarian metaorganisms as a whole. Here, we investigated the bacterial communities of different Aiptasia host-symbiont combinations under long-term heat stress in laboratory conditions. Following a 16S rRNA gene sequencing approach we were able to detect significant differences in the bacterial composition and structure of Aiptasia reared at different temperatures. A higher number of taxa (i.e., species richness), and consequently increased α-diversity and β-dispersion, were observed in the microbiomes of heat-stressed individuals across all host strains and experimental batches. Our findings are in line with the recently proposed Anna Karenina principle (AKP) for animal microbiomes, which states that dysbiotic or stressed organisms have a more variable and unstable microbiome than healthy ones. Microbial interactions affect the fitness and survival of their hosts, thus exploring the AKP effect on animal microbiomes is important to understand host resilience. Our data contributes to the current knowledge of the Aiptasia holobiont and to the growing field of study of host-associated microbiomes.

RevDate: 2019-06-16

Hammer TJ, Sanders JG, N Fierer (2019)

Not all animals need a microbiome.

FEMS microbiology letters, 366(10):.

It is often taken for granted that all animals host and depend upon a microbiome, yet this has only been shown for a small proportion of species. We propose that animals span a continuum of reliance on microbial symbionts. At one end are the famously symbiont-dependent species such as aphids, humans, corals and cows, in which microbes are abundant and important to host fitness. In the middle are species that may tolerate some microbial colonization but are only minimally or facultatively dependent. At the other end are species that lack beneficial symbionts altogether. While their existence may seem improbable, animals are capable of limiting microbial growth in and on their bodies, and a microbially independent lifestyle may be favored by selection under some circumstances. There is already evidence for several 'microbiome-free' lineages that represent distantly related branches in the animal phylogeny. We discuss why these animals have received such little attention, highlighting the potential for contaminants, transients, and parasites to masquerade as beneficial symbionts. We also suggest ways to explore microbiomes that address the limitations of DNA sequencing. We call for further research on microbiome-free taxa to provide a more complete understanding of the ecology and evolution of macrobe-microbe interactions.

RevDate: 2019-05-26

Horváthová T, Babik W, Kozłowski J, et al (2019)

Vanishing benefits - The loss of actinobacterial symbionts at elevated temperatures.

Journal of thermal biology, 82:222-228.

Only a few insect species are known to engage in symbiotic associations with antibiotic-producing Actinobacteria and profit from this kind of protection against pathogens. However, it still remains elusive how widespread the symbiotic interactions with Actinobacteria in other organisms are and how these partnerships benefit the hosts in terms of the growth and survival. We characterized a drastic temperature-induced change in the occurrence of Actinobacteria in the gut of the terrestrial isopod Porcellio scaber reared under two different temperature (15 °C and 22 °C) and oxygen conditions (10% and 22% O2) using 16S rRNA gene sequencing. We show that the relative abundance of actinobacterial gut symbionts correlates with increased host growth at lower temperature. Actinobacterial symbionts were almost completely absent at 22 °C under both high and low oxygen conditions. In addition, we identified members of nearly half of the known actinobacterial families in the isopod microbiome, and most of these include members that are known to produce antibiotics. Our study suggests that hosting diverse actinobacterial symbionts may provide conditions favorable for host growth. These findings show how a temperature-driven decline in microbiome diversity may cause a loss of beneficial functions with negative effects on ectotherms.

RevDate: 2019-07-24

Sartor F, Eelderink-Chen Z, Aronson B, et al (2019)

Are There Circadian Clocks in Non-Photosynthetic Bacteria?.

Biology, 8(2): pii:biology8020041.

Circadian clocks in plants, animals, fungi, and in photosynthetic bacteria have been well-described. Observations of circadian rhythms in non-photosynthetic Eubacteria have been sporadic, and the molecular basis for these potential rhythms remains unclear. Here, we present the published experimental and bioinformatical evidence for circadian rhythms in these non-photosynthetic Eubacteria. From this, we suggest that the timekeeping functions of these organisms will be best observed and studied in their appropriate complex environments. Given the rich temporal changes that exist in these environments, it is proposed that microorganisms both adapt to and contribute to these daily dynamics through the process of temporal mutualism. Understanding the timekeeping and temporal interactions within these systems will enable a deeper understanding of circadian clocks and temporal programs and provide valuable insights for medicine and agriculture.

RevDate: 2019-06-10

Bosch TCG, Guillemin K, M McFall-Ngai (2019)

Evolutionary "Experiments" in Symbiosis: The Study of Model Animals Provides Insights into the Mechanisms Underlying the Diversity of Host-Microbe Interactions.

BioEssays : news and reviews in molecular, cellular and developmental biology [Epub ahead of print].

Current work in experimental biology revolves around a handful of animal species. Studying only a few organisms limits science to the answers that those organisms can provide. Nature has given us an overwhelming diversity of animals to study, and recent technological advances have greatly accelerated the ability to generate genetic and genomic tools to develop model organisms for research on host-microbe interactions. With the help of such models the authors therefore hope to construct a more complete picture of the mechanisms that underlie crucial interactions in a given metaorganism (entity consisting of a eukaryotic host with all its associated microbial partners). As reviewed here, new knowledge of the diversity of host-microbe interactions found across the animal kingdom will provide new insights into how animals develop, evolve, and succumb to the disease.

RevDate: 2019-07-05
CmpDate: 2019-07-05

Lachnit T, Bosch TCG, P Deines (2019)

Exposure of the Host-Associated Microbiome to Nutrient-Rich Conditions May Lead to Dysbiosis and Disease Development-an Evolutionary Perspective.

mBio, 10(3): pii:mBio.00355-19.

Inflammatory diseases, such as inflammatory bowel diseases, are dramatically increasing worldwide, but an understanding of the underlying factors is lacking. We here present an ecoevolutionary perspective on the emergence of inflammatory diseases. We propose that adaptation has led to fine-tuned host-microbe interactions, which are maintained by secreted host metabolites nourishing the associated microbes. A constant elevation of nutrients in the gut environment leads to an increased activity and changed functionality of the microbiota, thus severely disturbing host-microbe interactions and leading to dysbiosis and disease development. In the past, starvation and pathogen infections, causing diarrhea, were common incidences that reset the gut bacterial community to its "human-specific-baseline." However, these natural clearing mechanisms have been virtually eradicated in developed countries, allowing a constant uncontrolled growth of bacteria. This leads to an increase of bacterial products that stimulate the immune system and ultimately might initiate inflammatory reactions.

RevDate: 2019-06-15

van der Loos LM, Eriksson BK, J Falcão Salles (2019)

The Macroalgal Holobiont in a Changing Sea.

Trends in microbiology, 27(7):635-650.

When studying the effects of climate change on eukaryotic organisms we often oversee a major ecological process: the interaction with microbes. Eukaryotic hosts and microbes form functional units, termed holobionts, where microbes play crucial roles in host functioning. Environmental stress may disturb these complex mutualistic relations. Macroalgae form the foundation of coastal ecosystems worldwide and provide important ecosystem services - services they could likely not provide without their microbial associates. Still, today we do not know how environmental stress will affect the macroalgal holobiont in an increasingly changing ocean. In this review, we provide a conceptual framework that contributes to understanding the different levels at which the holobiont and environment interact, and we suggest a manipulative experimental approach as a guideline for future research.

RevDate: 2019-04-28

Morrissey KL, Çavaş L, Willems A, et al (2019)

Disentangling the Influence of Environment, Host Specificity and Thallus Differentiation on Bacterial Communities in Siphonous Green Seaweeds.

Frontiers in microbiology, 10:717.

Siphonous green seaweeds, such as Caulerpa, are among the most morphologically complex algae with differentiated algal structures (morphological niches). Caulerpa is also host to a rich diversity of bacterial endo- and epibionts. The degree to which these bacterial communities are species-, or even niche-specific remains largely unknown. To address this, we investigated the diversity of bacteria associated to different morphological niches of both native and invasive species of Caulerpa from different geographic locations along the Turkish coastline of the Aegean sea. Associated bacteria were identified using the 16S rDNA marker gene for three morphological niches, such as the endobiome, epibiome, and rhizobiome. Bacterial community structure was explored and deterministic factors behind bacterial variation were investigated. Of the total variation, only 21.5% could be explained. Pronounced differences in bacterial community composition were observed and variation was partly explained by a combination of host species, biogeography and nutrient levels. The majority of the explained bacterial variation within the algal holobiont was attributed to the micro-environments established by distinct morphological niches. This study further supports the hypothesis that the bacterial assembly is largely stochastic in nature and bacterial community structure is most likely linked to functional genes rather than taxonomy.

RevDate: 2019-07-23

Ye S, Badhiwala KN, Robinson JT, et al (2019)

Thermal plasticity of a freshwater cnidarian holobiont: detection of trans-generational effects in asexually reproducing hosts and symbionts.

The ISME journal, 13(8):2058-2067.

Understanding factors affecting the susceptibility of organisms to thermal stress is of enormous interest in light of our rapidly changing climate. When adaptation is limited, thermal acclimation and deacclimation abilities of organisms are critical for population persistence through a period of thermal stress. Holobionts (hosts plus associated symbionts) are key components of various ecosystems, such as coral reefs, yet the contributions of their two partners to holobiont thermal plasticity are poorly understood. Here, we tested thermal plasticity of the freshwater cnidarian Hydra viridissima (green hydra) using individual behavior and population responses. We found that algal presence initially reduced hydra thermal tolerance. Hydra with algae (symbiotic hydra) had comparable acclimation rates, deacclimation rates, and thermal tolerance after acclimation to those without algae (aposymbiotic hydra) but they had higher acclimation capacity. Acclimation of the host (hydra) and/or symbiont (algae) to elevated temperatures increased holobiont thermal tolerance and these effects persisted for multiple asexual generations. In addition, acclimated algae presence enhanced hydra fitness under prolonged sublethal thermal stress, especially when food was limited. Our study indicates while less intense but sublethal stress may favor symbiotic organisms by allowing them to acclimate, sudden large, potentially lethal fluctuations in climate stress likely favor aposymbiotic organisms. It also suggests that thermally stressed colonies of holobionts could disperse acclimated hosts and/or symbionts to other colonies, thereby reducing their vulnerability to climate change.

RevDate: 2019-04-21

Inkpen SA (2019)

Health, ecology and the microbiome.

eLife, 8: pii:47626.

Advances in microbiomics have changed the way in which many researchers think about health and disease. These changes have also raised a number of philosophical questions around these topics, such as the types of living systems to which these concepts can be applied. Here, I discuss the human microbiome from two perspectives: the first treats the microbiome as part of a larger system that includes the human; the second treats the microbiome as an independent ecosystem that provides services to humans. Drawing on the philosophy of medicine and ecology, I explore two questions: i) how can we make sense of disease and dysfunction in these two perspectives? ii) are these two perspectives complimentary or do they compete with each other?

RevDate: 2019-05-03
CmpDate: 2019-05-03

Jaspers C, Fraune S, Arnold AE, et al (2019)

Resolving structure and function of metaorganisms through a holistic framework combining reductionist and integrative approaches.

Zoology (Jena, Germany), 133:81-87.

Current research highlights the importance of associated microbes in contributing to the functioning, health, and even adaptation of their animal, plant, and fungal hosts. As such, we are witnessing a shift in research that moves away from focusing on the eukaryotic host sensu stricto to research into the complex conglomerate of the host and its associated microorganisms (i.e., microbial eukaryotes, archaea, bacteria, and viruses), the so-called metaorganism, as the biological entity. While recent research supports and encourages the adoption of such an integrative view, it must be understood that microorganisms are not involved in all host processes and not all associated microorganisms are functionally important. As such, our intention here is to provide a critical review and evaluation of perspectives and limitations relevant to studying organisms in a metaorganism framework and the functional toolbox available to do so. We note that marker gene-guided approaches that primarily characterize microbial diversity are a first step in delineating associated microbes but are not sufficient to establish proof of their functional relevance. More sophisticated tools and experiments are necessary to reveal the specific functions of associated microbes. This can be accomplished through the study of metaorganisms in less complex environments, the targeted manipulation of microbial associates, or work at the mechanistic level with the toolbox available in model systems. We conclude that the metaorganism framework is a powerful new concept to help provide answers to longstanding biological questions such as the evolution and ecology of organismal complexity and the importance of organismal symbioses to ecosystem functioning. The intricacy of the metaorganism requires a holistic framework combining reductionist and integrative approaches to resolve the structure and function of its member species and to disclose the various roles that microorganisms play in the biology of their hosts.

RevDate: 2019-06-21
CmpDate: 2019-06-21

Munzi S, Cruz C, A Corrêa (2019)

When the exception becomes the rule: An integrative approach to symbiosis.

The Science of the total environment, 672:855-861.

Symbiosis, mainly due to the advances in -omics technology and to the microbiome revolution, is being increasingly acknowledged as fundamental to explain any aspect of life existence. Previously considered an exception, a peculiar characteristic of few systems like lichens, corals and mycorrhizas, symbiosis is nowadays recognized as the rule, with the microbiome being part of all living entities and systems. However, our knowledge of the ecological meaning and functioning of many symbiotic systems is still limited. Here, we discuss a new, integrative approach based on current findings that looks at commonalities among symbiotic systems to produce theoretical models and conceptual knowledge that would allow a more efficient exploitation of symbiosis-based biotechnologies. The microbiome recruitment and assemblage processes are indicated as one of the potential targets where a holistic approach could bring advantages. Finally, we reflect on the potential socio-economic and environmental consequences of a symbiotic view of the world, where co-dependence is the matrix of life.

RevDate: 2019-04-14

Mills JG, Brookes JD, Gellie NJC, et al (2019)

Relating Urban Biodiversity to Human Health With the 'Holobiont' Concept.

Frontiers in microbiology, 10:550.

A relatively unaccounted ecosystem service from biodiversity is the benefit to human health via symbiotic microbiota from our environment. This benefit occurs because humans evolved alongside microbes and have been constantly exposed to diverse microbiota. Plants and animals, including humans, are organised as a host with symbiotic microbiota, whose collective genome and life history form a single holobiont. As such, there are interdependencies between biodiversity, holobionts, and public health which lead us to argue that human health outcomes could be improved by increasing contact with biodiversity in an urban context. We propose that humans, like all holobionts, likely require a diverse microbial habitat to appropriate resources for living healthy, long lives. We discuss how industrial urbanisation likely disrupts the symbiosis between microbiota and their hosts, leading to negative health outcomes. The industrialised urban habitat is low in macro and microbial biodiversity and discourages contact with beneficial environmental microbiota. These habitat factors, alongside diet, antibiotics, and others, are associated with the epidemic of non-communicable diseases in these societies. We suggest that restoration of urban microbial biodiversity and micro-ecological processes through microbiome rewilding can benefit holobiont health and aid in treating the urban non-communicable disease epidemic. Further, we identify research gaps and some solutions to economic and strategic hurdles in applying microbiome rewilding into daily urban life.

RevDate: 2019-08-13
CmpDate: 2019-08-13

de Oliveira BFR, Cavalcanti MD, de Oliveira Nunes S, et al (2019)

Paraclostridium is the Main Genus of Anaerobic Bacteria Isolated from New Species of the Marine Sponge Plakina in the Brazilian Southeast Coast.

Current microbiology, 76(6):713-722.

Despite the broad assessment of sponge bacterial diversity through cultivation-independent and dependent strategies, the knowledge focusing on cultivable anaerobes from this holobiont is still incipient. Plakina is a genus with the highest number of described species from the smallest of poriferan classes, Homoscleromorpha. The Brazilian Atlantic coast has been presenting itself as a hotspot for the discovery of new plakinidae species, with initial surveys just now concerning to characterize their microbiome. The current study aimed to isolate and identify strict anaerobes from recently described species of Plakina collected at the coast of Cabo Frio, RJ. Samples of four sympatric morphotypes of Plakina cyanorosea and Plakina cabofriense were collected on the coast of Cabo Frio, RJ. Using five different culture media, a total of 93 bacterial isolates were recovered, among which 60 were strict anaerobes and, ultimately, 34 remaining viable. A total of 76.5% from these strains were mostly identified as Clostridium bifermentans by mass spectrometry and 82.4% identified by 16S rRNA sequencing, almost all of them affiliated to the genus Paraclostridium, and with one isolate identified as Clostridium butyricum by both techniques. None of the anaerobic bacteria exhibited antimicrobial activity by the adopted screening test. The present work highlights not only the need for cultivation and characterization of the anaerobic microbiota from marine sponges but also adds the existing scarce knowledge of culturable bacterial communities from Homoscleromorph sponges from Brazilian coast.

RevDate: 2019-04-11

Qiu Z, Coleman MA, Provost E, et al (2019)

Future climate change is predicted to affect the microbiome and condition of habitat-forming kelp.

Proceedings. Biological sciences, 286(1896):20181887.

Climate change is driving global declines of marine habitat-forming species through physiological effects and through changes to ecological interactions, with projected trajectories for ocean warming and acidification likely to exacerbate such impacts in coming decades. Interactions between habitat-formers and their microbiomes are fundamental for host functioning and resilience, but how such relationships will change in future conditions is largely unknown. We investigated independent and interactive effects of warming and acidification on a large brown seaweed, the kelp Ecklonia radiata, and its associated microbiome in experimental mesocosms. Microbial communities were affected by warming and, during the first week, by acidification. During the second week, kelp developed disease-like symptoms previously observed in the field. The tissue of some kelp blistered, bleached and eventually degraded, particularly under the acidification treatments, affecting photosynthetic efficiency. Microbial communities differed between blistered and healthy kelp for all treatments, except for those under future conditions of warming and acidification, which after two weeks resembled assemblages associated with healthy hosts. This indicates that changes in the microbiome were not easily predictable as the severity of future climate scenarios increased. Future ocean conditions can change kelp microbiomes and may lead to host disease, with potentially cascading impacts on associated ecosystems.

RevDate: 2019-05-02

Paix B, Othmani A, Debroas D, et al (2019)

Temporal covariation of epibacterial community and surface metabolome in the Mediterranean seaweed holobiont Taonia atomaria.

Environmental microbiology [Epub ahead of print].

An integrative multi-omics approach allowed monthly variations for a year of the surface metabolome and the epibacterial community of the Mediterranean Phaeophyceae Taonia atomaria to be investigated. The LC-MS-based metabolomics and 16S rDNA metabarcoding data sets were integrated in a multivariate meta-omics analysis (multi-block PLS-DA from the MixOmic DIABLO analysis) showing a strong seasonal covariation (Mantel test: p < 0.01). A network based on positive and negative correlations between the two data sets revealed two clusters of variables, one relative to the 'spring period' and a second to the 'summer period'. The 'spring period' cluster was mainly characterized by dipeptides positively correlated with a single bacterial taxon of the Alteromonadaceae family (BD1-7 clade). Moreover, 'summer' dominant epibacterial taxa from the second cluster (including Erythrobacteraceae, Rhodospirillaceae, Oceanospirillaceae and Flammeovirgaceae) showed positive correlations with few metabolites known as macroalgal antifouling defences [e.g. dimethylsulphoniopropionate (DMSP) and proline] which exhibited a key role within the correlation network. Despite a core community that represents a significant part of the total epibacteria, changes in the microbiota structure associated with surface metabolome variations suggested that both environment and algal host shape the bacterial surface microbiota.

RevDate: 2019-04-07

Vannier N, Mony C, Bittebiere AK, et al (2019)

Clonal Plants as Meta-Holobionts.

mSystems, 4(2): pii:mSystems00213-18.

The holobiont concept defines a given organism and its associated symbionts as a potential level of selection over evolutionary time. In clonal plants, recent experiments demonstrated vertical transmission of part of the microbiota from one ramet (i.e., potentially autonomous individual) to another within the clonal network (i.e., connections by modified stems present in ∼35% of all plants). Because of this heritability, and potentially reciprocal exchange of microbes between generations of ramets, we propose to extend the existing holobiont framework to the concept of meta-holobiont. A meta-holobiont is a network of holobionts that can exchange biomolecules and microbiota across generations, thus impacting the fitness of both biological scales: holobionts and meta-holobionts. Specifically, meta-holobiont dynamics can result in sharing, specialization, and division of labor across plant clonal generations. This paper, which coins the meta-holobiont concept, is expected to stimulate discussion and to be applied beyond the context of networked clonal plants (e.g., to social insects).

RevDate: 2019-03-29

Bayliss SLJ, Scott ZR, Coffroth MA, et al (2019)

Genetic variation in Breviolum antillogorgium, a coral reef symbiont, in response to temperature and nutrients.

Ecology and evolution, 9(5):2803-2813 pii:ECE34959.

Symbionts within the family Symbiodiniaceae are important on coral reefs because they provide significant amounts of carbon to many different reef species. The breakdown of this mutualism that occurs as a result of increasingly warmer ocean temperatures is a major threat to coral reef ecosystems globally. Recombination during sexual reproduction and high rates of somatic mutation can lead to increased genetic variation within symbiont species, which may provide the fuel for natural selection and adaptation. However, few studies have asked whether such variation in functional traits exists within these symbionts. We used several genotypes of two closely related species, Breviolum antillogorgium and B. minutum, to examine variation of traits related to symbiosis in response to increases in temperature or nitrogen availability in laboratory cultures. We found significant genetic variation within and among symbiont species in chlorophyll content, photosynthetic efficiency, and growth rate. Two genotypes showed decreases in traits in response to increased temperatures predicted by climate change, but one genotype responded positively. Similarly, some genotypes within a species responded positively to high-nitrogen environments, such as those expected within hosts or eutrophication associated with global change, while other genotypes in the same species responded negatively, suggesting context-dependency in the strength of mutualism. Such variation in traits implies that there is potential for natural selection on symbionts in response to temperature and nutrients, which could confer an adaptive advantage to the holobiont.

RevDate: 2019-05-01

Tarquinio F, Hyndes GA, Laverock B, et al (2019)

The seagrass holobiont: understanding seagrass-bacteria interactions and their role in seagrass ecosystem functioning.

FEMS microbiology letters, 366(6):.

This review shows that the presence of seagrass microbial community is critical for the development of seagrasses; from seed germination, through to phytohormone production and enhanced nutrient availability, and defence against pathogens and saprophytes. The tight seagrass-bacterial relationship highlighted in this review supports the existence of a seagrass holobiont and adds to the growing evidence for the importance of marine eukaryotic microorganisms in sustaining vital ecosystems. Incorporating a micro-scale view on seagrass ecosystems substantially expands our understanding of ecosystem functioning and may have significant implications for future seagrass management and mitigation against human disturbance.

RevDate: 2019-08-12

Thomashow LS, Kwak YS, DM Weller (2019)

Root-associated microbes in sustainable agriculture: models, metabolites and mechanisms.

Pest management science, 75(9):2360-2367.

Since the discovery of penicillin in 1928 and throughout the 'age of antibiotics' from the 1940s until the 1980s, the detection of novel antibiotics was restricted by lack of knowledge about the distribution and ecology of antibiotic producers in nature. The discovery that a phenazine compound produced by Pseudomonas bacteria could suppress soilborne plant pathogens, and its recovery from rhizosphere soil in 1990, provided the first incontrovertible evidence that natural metabolites could control plant pathogens in the environment and opened a new era in biological control by root-associated rhizobacteria. More recently, the advent of genomics, the availability of highly sensitive bioanalytical instrumentation, and the discovery of protective endophytes have accelerated progress toward overcoming many of the impediments that until now have limited the exploitation of beneficial plant-associated microbes to enhance agricultural sustainability. Here, we present key developments that have established the importance of these microbes in the control of pathogens, discuss concepts resulting from the exploration of classical model systems, and highlight advances emerging from ongoing investigations. © 2019 Society of Chemical Industry.

RevDate: 2019-03-29

Weigel BL, CA Pfister (2019)

Successional Dynamics and Seascape-Level Patterns of Microbial Communities on the Canopy-Forming Kelps Nereocystis luetkeana and Macrocystis pyrifera.

Frontiers in microbiology, 10:346.

Canopy-forming kelps create underwater forests that are among the most productive marine ecosystems. On the Pacific coast of North America, two canopy-forming kelps with contrasting life histories co-occur; Macrocystis pyrifera, a perennial species, and Nereocystis luetkeana, an annual species. Kelp blade-associated microbes were sampled from 12 locations across a spatial gradient in Washington, United States, from the outer Pacific Coast to Puget Sound. Microbial communities were characterized using next-generation Illumina sequencing of 16S rRNA genes. At higher taxonomic levels (bacterial phylum and class), canopy-forming kelps hosted remarkably similar microbial communities, but at the amplicon sequence variant level, microbial communities on M. pyrifera and N. luetkeana were host-specific and distinct from free-living bacteria in the surrounding seawater. Microbial communities associated with blades of each kelp species displayed significant geographic variation. The microbiome of N. luetkeana changed along the spatial gradient and was significantly correlated to salinity, with outer Pacific coast sites enriched in Bacteroidetes (family Saprospiraceae) and Gammaproteobacteria (Granulosicoccus sp.), and southern Puget Sound sites enriched in Alphaproteobacteria (family Hyphomonadaceae). We also examined microbial community development and succession on meristematic and apical N. luetkeana blade tissues throughout the summer growing season on Tatoosh Island, WA. Across all dates, microbial communities were less diverse on younger, meristematic blade tissue compared to the older, apical tissues. In addition, phylogenetic relatedness among microbial taxa increased from meristematic to apical blade tissues, suggesting that the addition of microbial taxa to the community was a non-random process that selected for certain phylogenetic groups of microbes. Microbial communities on older, apical tissues displayed significant temporal variation throughout the summer and microbial taxa that were differentially abundant over time displayed clear patterns of community succession. Overall, we report that host species identity, geographic location, and blade tissue age shape the microbial communities on canopy-forming kelps.

RevDate: 2019-07-11

Reverter M, Tribalat MA, Pérez T, et al (2018)

Metabolome variability for two Mediterranean sponge species of the genus Haliclona: specificity, time, and space.

Metabolomics : Official journal of the Metabolomic Society, 14(9):114 pii:10.1007/s11306-018-1401-5.

INTRODUCTION: The study of natural variation of metabolites brings valuable information on the physiological state of the organisms as well as their phenotypic traits. In marine organisms, metabolome variability has mostly been addressed through targeted studies on metabolites of ecological or pharmaceutical interest. However, comparative metabolomics has demonstrated its potential to address the overall and complex metabolic variability of organisms.

OBJECTIVES: In this study, the intraspecific (temporal and spatial) variability of two Mediterranean Haliclona sponges (H. fulva and H. mucosa) was investigated through an untargeted and then targeted metabolomics approach and further compared to their interspecific variability.

METHODS: Samples of both species were collected monthly during 1 year in the coralligenous habitat of the Northwestern Mediterranean sae at Marseille and Nice. Their metabolomic profiles were obtained by UHPLC-QqToF analyses.

RESULTS: Marked variations were noticed in April and May for both species including a decrease in Shannon's diversity and concentration in specialized metabolites together with an increase in fatty acids and lyso-PAF like molecules. Spatial variations across different sampling sites could also be observed for both species, however in a lesser extent.

CONCLUSIONS: Synchronous metabolic changes possibly triggered by physiological factors like reproduction and/or environmental factors like an increase in the water temperature were highlighted for both Mediterranean Haliclona species inhabiting close habitats but displaying different biosynthetic pathways. Despite significative intraspecific variations, metabolomic variability remains minor when compared to interspecific variations for these congenerous species, therefore suggesting the predominance of genetic information of the holobiont in the observed metabolome.

RevDate: 2019-02-27

Kong HG, Kim HH, Chung JH, et al (2019)

The Galleria mellonella Hologenome Supports Microbiota-Independent Metabolism of Long-Chain Hydrocarbon Beeswax.

Cell reports, 26(9):2451-2464.e5.

The greater wax moth, Galleria mellonella, degrades wax and plastic molecules. Despite much interest, the genetic basis of these hallmark traits remains poorly understood. Herein, we assembled high-quality genome and transcriptome data from G. mellonella to investigate long-chain hydrocarbon wax metabolism strategies. Specific carboxylesterase and lipase and fatty-acid-metabolism-related enzymes in the G. mellonella genome are transcriptionally regulated during feeding on beeswax. Strikingly, G. mellonella lacking intestinal microbiota successfully decomposes long-chain fatty acids following wax metabolism, although the intestinal microbiome performs a supplementary role in short-chain fatty acid degradation. Notably, final wax derivatives were detected by gas chromatography even in the absence of gut microbiota. Our findings provide insight into wax moth adaptation and may assist in the development of unique wax-degradation strategies with a similar metabolic approach for a plastic molecule polyethylene biodegradation using organisms without intestinal microbiota.

RevDate: 2019-04-08
CmpDate: 2019-04-08

Fuentes A (2019)

Holobionts, Multispecies Ecologies, and the Biopolitics of Care: Emerging Landscapes of Praxis in a Medical Anthropology of the Anthropocene.

Medical anthropology quarterly, 33(1):156-162.

Medical anthropology, given its diversity of practical and historical entanglements with (and outside of) numerous threads of anthropology, is a key site for productive theoretical and methodological confluences in the Anthropocene. Multispecies approaches, ethnographically, theoretically and methodologically, are developing as central locations for the hybridization and mingling of diverse and innovative research questions, particularly those engaging the processes, patterns, and constructs of health.

RevDate: 2019-03-03

Chakravarti LJ, Negri AP, MJH van Oppen (2019)

Thermal and Herbicide Tolerances of Chromerid Algae and Their Ability to Form a Symbiosis With Corals.

Frontiers in microbiology, 10:173.

Reef-building corals form an obligate symbiosis with photosynthetic microalgae in the family Symbiodiniaceae that meet most of their energy requirements. This symbiosis is under threat from the unprecedented rate of ocean warming as well as the simultaneous pressure of local stressors such as poor water quality. Only 1°C above mean summer sea surface temperatures (SSTs) on the Great Barrier Reef (GBR) can trigger the loss of Symbiodiniaceae from the host, and very low concentrations of the most common herbicide, diuron, can disrupt the photosynthetic activity of microalgae. In an era of rapid environmental change, investigation into the assisted evolution of the coral holobiont is underway in an effort to enhance the resilience of corals. Apicomplexan-like microalgae were discovered in 2008 and the Phylum Chromerida (chromerids) was created. Chromerids have been isolated from corals and contain a functional photosynthetic plastid. Their discovery therefore opens a new avenue of research into the use of alternative/additional photosymbionts of corals. However, only two studies to-date have investigated the symbiotic nature of Chromera velia with corals and thus little is known about the coral-chromerid relationship. Furthermore, the response of chromerids to environmental stressors has not been examined. Here we tested the performance of four chromerid strains and the common dinoflagellate symbiont Cladocopium goreaui (formerly Symbiodinium goreaui, ITS2 type C1) in response to elevated temperature, diuron and their combined exposure. Three of the four chromerid strains exhibited high thermal tolerances and two strains showed exceptional herbicide tolerances, greater than observed for any photosynthetic microalgae, including C. goreaui. We also investigated the onset of symbiosis between the chromerids and larvae of two common GBR coral species under ambient and stress conditions. Levels of colonization of coral larvae with the chromerid strains were low compared to colonization with C. goreaui. We did not observe any overall negative or positive larval fitness effects of the inoculation with chromerid algae vs. C. goreaui. However, we cannot exclude the possibility that chromerid algae may have more important roles in later coral life stages and recommend this be the focus of future studies.

RevDate: 2019-06-04
CmpDate: 2019-06-04

Estellé J (2019)

Benefits from the joint analysis of host genomes and metagenomes: Select the holobiont.

Journal of animal breeding and genetics = Zeitschrift fur Tierzuchtung und Zuchtungsbiologie, 136(2):75-76.

RevDate: 2019-02-13

Glasl B, Smith CE, Bourne DG, et al (2019)

Disentangling the effect of host-genotype and environment on the microbiome of the coral Acropora tenuis.

PeerJ, 7:e6377 pii:6377.

Genotype-specific contributions to the environmental tolerance and disease susceptibility of corals are widely accepted. Yet our understanding of how host genotype influences the composition and stability of the coral microbiome subjected to environmental fluctuations is limited. To gain insight into the community dynamics and environmental stability of microbiomes associated with distinct coral genotypes, we assessed the microbial community associated with Acropora tenuis under single and cumulative pressure experiments. Experimental treatments comprised either a single pulse of reduced salinity (minimum of 28 psu) or exposure to the cumulative pressures of reduced salinity (minimum of 28 psu), elevated seawater temperature (+2 °C), elevated pCO2 (900 ppm), and the presence of macroalgae. Analysis of 16S rRNA gene amplicon sequence data revealed that A. tenuis microbiomes were highly host-genotype specific and maintained high compositional stability irrespective of experimental treatment. On average, 48% of the A. tenuis microbiome was dominated by Endozoicomonas. Amplicon sequence variants (ASVs) belonging to this genus were significantly different between host individuals. Although no signs of stress were evident in the coral holobiont and the vast majority of ASVs remained stable across treatments, a microbial indicator approach identified 26 ASVs belonging to Vibrionaceae, Rhodobacteraceae, Hahellaceae, Planctomycetes, Phylobacteriaceae, Flavobacteriaceae, and Cryomorphaceae that were significantly enriched in corals exposed to single and cumulative stressors. While several recent studies have highlighted the efficacy of microbial indicators as sensitive markers for environmental disturbance, the high host-genotype specificity of coral microbiomes may limit their utility and we therefore recommend meticulous control of host-genotype effects in coral microbiome research.

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ESP Quick Facts

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In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

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In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

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When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

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With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.

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Selected Bibliographies

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