Seasonal dynamics of Chironomus transvaalensis populations and the microbial community composition of their egg masses

ABSTRACT Chironomids (Diptera; Chironomidae) are the most abundant insects in freshwater environments and are considered natural reservoirs of Vibrio cholerae. We monitored the annual dynamics of chironomid populations along with their microbiota in order to better understand host–microbiota interactions. Chironomus transvaalensis populations peaked biannually in August and May–June. The composition of the endogenous bacterial communities of their egg masses clustered in two groups according to the sampling periods August–November and May–July. Nevertheless, a core bacterial community (43%) was present in all egg-mass samples. The most abundant phyla were: Proteobacteria, Firmicutes, Cyanobacteria and Bacteroidetes. The abundance of several genera (e.g. Rheinheimera and Pseudomonas) was positively correlated with C. transvaalensis population dynamics, while a predator–prey interaction was observed between the relative abundance of Vibrio OTUs and C. transvaalensis population size. Chironomids are known to tolerate toxic and stress conditions, and our results demonstrated that bacterial genera that may protect the insect under these conditions are present in the egg masses. After hatching, the first larval meal is the gelatinous matrix that surrounds the eggs. This meal contains a probiotic consortium that may protect the larva during its metamorphosis. The results provide important insights into the host–microbe interactions of chironomids.

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Bacterial community assembly in Atlantic cod larvae (Gadus morhua): contributions of ecological processes and metacommunity structure

FEMS Microbiology Ecology ◽

10.1093/femsec/fiaa163 ◽

2020 ◽

Vol 96 (9) ◽

Cited By ~ 1

Author(s):

Ragnhild I Vestrum ◽

Kari J K Attramadal ◽

Olav Vadstein ◽

Madeleine Stenshorne Gundersen ◽

Ingrid Bakke

Keyword(s):

Community Assembly ◽

Bacterial Communities ◽

Atlantic Cod ◽

Animal Health ◽

Striking Difference ◽

Ecological Processes ◽

Opportunistic Bacteria ◽

Atlantic Cod Larvae ◽

Microbe Interactions ◽

Host Microbe Interactions

ABSTRACT Many studies demonstrate the importance of the commensal microbiomes to animal health and development. However, the initial community assembly process is poorly understood. It is unclear to what extent the hosts select for their commensal microbiota, whether stochastic processes contribute, and how environmental conditions affect the community assembly. We investigated community assembly in Atlantic cod larvae exposed to distinct microbial metacommunities. We aimed to quantify ecological processes influencing community assembly in cod larvae and to elucidate the complex relationship between the bacteria of the environment and the fish. Selection within the fish was the major determinant for community assembly, but drift resulted in inter-individual variation. The environmental bacterial communities were highly dissimilar from those associated with the fish. Still, differences in the environmental bacterial communities strongly influenced the fish communities. The most striking difference was an excessive dominance of a single OTU (Arcobacter) for larvae reared in two of the three systems. These larvae were exposed to environments with higher fractions of opportunistic bacteria, and we hypothesise that detrimental host–microbe interactions might have made the fish susceptible to Arcobacter colonisation. Despite strong selection within the host, this points to a possibility to steer the metacommunity towards mutualistic host–microbe interactions and improved fish health and survival.

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Fungal microbiomes are determined by host phylogeny and exhibit widespread associations with the bacterial microbiome

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2021.0552 ◽

2021 ◽

Vol 288 (1957) ◽

pp. 20210552

Author(s):

Xavier A. Harrison ◽

Allan D. McDevitt ◽

Jenny C. Dunn ◽

Sarah M. Griffiths ◽

Chiara Benvenuto ◽

...

Keyword(s):

Bacterial Communities ◽

Natural Populations ◽

Sample Type ◽

Fungal Community Composition ◽

Tissue Storage ◽

Bacterial Microbiome ◽

Host Phylogeny ◽

Microbe Interactions ◽

Host Microbe Interactions ◽

Using Data

Interactions between hosts and their resident microbial communities are a fundamental component of fitness for both agents. Though recent research has highlighted the importance of interactions between animals and their bacterial communities, comparative evidence for fungi is lacking, especially in natural populations. Using data from 49 species, we present novel evidence of strong covariation between fungal and bacterial communities across the host phylogeny, indicative of recruitment by hosts for specific suites of microbes. Using co-occurrence networks, we demonstrate marked variation across host taxonomy in patterns of covariation between bacterial and fungal abundances. Host phylogeny drives differences in the overall richness of bacterial and fungal communities, but the effect of diet on richness was only evident in the mammalian gut microbiome. Sample type, tissue storage and DNA extraction method also affected bacterial and fungal community composition, and future studies would benefit from standardized approaches to sample processing. Collectively these data indicate fungal microbiomes may play a key role in host fitness and suggest an urgent need to study multiple agents of the animal microbiome to accurately determine the strength and ecological significance of host–microbe interactions.

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Host-associated fungal communities are determined by host phylogeny and exhibit widespread associations with the bacterial microbiome

10.1101/2020.07.07.177535 ◽

2020 ◽

Author(s):

Xavier A. Harrison ◽

Allan D. McDevitt ◽

Jenny C. Dunn ◽

Sarah Griffiths ◽

Chiara Benvenuto ◽

...

Keyword(s):

Bacterial Communities ◽

Natural Populations ◽

Fungal Communities ◽

Phylogenetic Distance ◽

Bacterial Microbiome ◽

Host Phylogeny ◽

Microbe Interactions ◽

Host Microbe Interactions ◽

Microbial Groups ◽

Taxonomic Groups

ABSTRACTInteractions between hosts and their resident microbial communities are a fundamental component of fitness for both agents. Despite a recent proliferation of research on interactions between animals and their associated bacterial communities, comparative evidence from fungal communities is lacking, especially in natural populations. This disparity means knowledge of host-microbe interactions is biased towards the bacterial microbiome. Using samples from 49 species from eight metazoan classes, we demonstrate that the ecological distance between both fungal and bacterial components of the microbiome shift in tandem with host phylogenetic distance. Though so-called phylosymbiosis has been shown in bacterial communities, we extend previous knowledge by demonstrating that the magnitude of shifts in fungal and bacterial community structure across host phylogeny are correlated. These data are indicative of coordinated recruitment by hosts for specific suites of microbes, and potentially selection for bacterial-fungal interactions across a broad taxonomic range of host species. Using co-occurrence networks comprising both microbial groups, we illustrate that fungi form a critical component of microbial interaction networks, and that the strength and frequency of such interactions vary across host taxonomic groups. Collectively these data indicate fungal microbiomes may play a key role in host fitness and suggest an urgent need to study multiple agents of the animal microbiome to accurately determine the strength and ecological significance of host-microbe interactions.

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Vibrio cholerae Hemagglutinin/Protease Degrades Chironomid Egg Masses

Applied and Environmental Microbiology ◽

10.1128/aem.69.7.4200-4204.2003 ◽

2003 ◽

Vol 69 (7) ◽

pp. 4200-4204 ◽

Cited By ~ 58

Author(s):

Malka Halpern ◽

Hanan Gancz ◽

Meir Broza ◽

Yechezkel Kashi

Keyword(s):

Vibrio Cholerae ◽

Diarrheal Disease ◽

Living Organism ◽

Egg Mass ◽

Free Living ◽

Egg Masses ◽

Natural Reservoir ◽

Gelatinous Matrix ◽

Extracellular Factor

ABSTRACT Cholera is a severe diarrheal disease caused by specific serogroups of Vibrio cholerae that are pathogenic to humans. The disease does not persist in a chronic state in humans or animals. The pathogen is naturally present as a free-living organism in the environment. Recently, it was suggested that egg masses of the nonbiting midge Chironomus sp. (Diptera) harbor and serve as a nutritive source for V. cholerae, thereby providing a natural reservoir for the organism. Here we report that V. cholerae O9, O1, and O139 supernatants lysed the gelatinous matrix of the chironomid egg mass and inhibited eggs from hatching. The extracellular factor responsible for the degradation of chironomid egg masses (egg mass degrading factor) was purified from V. cholerae O9 and O139 and was identified as the major secreted hemagglutinin/protease (HA/P) of V. cholerae. The substrate in the egg mass was characterized as a glycoprotein. These findings show that HA/P plays an important role in the interaction of V. cholerae and chironomid egg masses.

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Microbiota as Therapeutic Targets

Digestive Diseases ◽

10.1159/000445263 ◽

2016 ◽

Vol 34 (5) ◽

pp. 558-565 ◽

Cited By ~ 10

Author(s):

Ramnik J. Xavier

Keyword(s):

Gastrointestinal Tract ◽

Microbial Communities ◽

Association Studies ◽

Microbial Community Composition ◽

Great Promise ◽

Host Immune System ◽

Genome Wide Association Studies ◽

Microbe Interactions ◽

Host Microbe Interactions ◽

And Function

Background: Inflammatory bowel disease (IBD) represents a family of diseases including Crohn's disease and ulcerative colitis. IBD has garnered significant attention in recent years due to successes in 2 areas of basic science: complex human genetics and host-microbe interactions. Advances in understanding the genetics of IBD, mainly driven by genome-wide association studies, have identified more than 160 genetic loci that modulate the risk of disease. Notably, several of these genes have pointed to alterations in host-microbe interactions as being critical factors in pathogenesis. Investigations into the microbial communities of the gastrointestinal tract (or the ‘gut microbiome') in IBD have yielded important insights into several aspects of interactions between microbiota and the host immune system, including how alterations to microbial community composition and function have important consequences for immune homeostasis. Key Messages: The anatomy of the gastrointestinal tract plays a role in defining not only intestinal function, but also the microbial ecosystem that lives within the gut. Careful investigations into the composition and function of these microbial communities have suggested that patients with IBD have an imbalance in their gut microbiota, termed dysbiosis. These studies, as well as studies using samples from healthy individuals, have begun to uncover mechanisms of crosstalk between particular microbes (and microbial products) and immunomodulatory pathways, alterations which may drive immune diseases such as IBD. Conclusions: Investigations into the role of the microbiome in IBD have provided important clues to potential pathogenic mechanisms. Harnessing this knowledge to develop therapeutics and identify biomarkers is currently a major translational goal, holding great promise for clinically meaningful progress.

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Old and new models for studying host-microbe interactions in health and disease:C. difficileas an example

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00341.2016 ◽

2017 ◽

Vol 312 (6) ◽

pp. G623-G627 ◽

Cited By ~ 2

Author(s):

Vincent B. Young

Keyword(s):

Human Health ◽

Bacterial Communities ◽

Human Microbiome ◽

Model Systems ◽

Microbe Interactions ◽

Health And Disease ◽

Indigenous Microbiota ◽

Pathogenic Microbes ◽

Host Microbe Interactions ◽

Insight Into

There has been an explosion of interest in studying the indigenous microbiota, which plays an important role in human health and disease. Traditionally, the study of microbes in relationship to human health involved consideration of individual microbial species that caused classical infectious diseases. With the interest in the human microbiome, an appreciation of the influence that complex communities of microbes can have on their environment has developed. When considering either individual pathogenic microbes or a symbiotic microbial community, researchers have employed a variety of model systems with which they can study the host-microbe interaction. With the use of studies of infections with the toxin-producing bacterium Clostridium difficile as a model for both a pathogen and beneficial bacterial communities as an example, this review will summarize and compare various model systems that can be used to gain insight into the host-microbe interaction.

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