Project description:This study examined the functional response of a host (zebrafish) to implantation of a conspecific or allospecific (goldfish) gastrointestinal (GIT) microbiome followed by diet manipulation and the repercussions of these manipulations on host GIT physiology. Implantation of a native zebrafish biome successfully reintroduced wildtype (WT) communities with the exception of several rare, phylogenetically distant species. Implantation of a foreign goldfish biome created communities that were distinct from WT, suggesting that the seeding community created substantial differences from the native host communities. A mismatched ?natural? diet and an implanted allospecific biome enriched for rarer and more phylogenetically diverse bacteria. Transcriptional changes within the GIT clustered in relationship to biome treatments, mirroring clustering of biome implants. Implantation of an allospecific biome along with an altered diet markedly down-regulated approximately 70% of the transcripts involved in cholesterol biosynthesis, while tissue content analysis revealed an increase in total tissue cholesterol. Furthermore, transcripts involved in lipogenesis pathways were significantly downregulated and correlated with a striking decrease in intestinal lipase activity driven by both biome and diet. Glucose-6P dehydrogenase (G6PD) activities increased during dietary manipulations regardless of biome, while the allospecific biome down-regulated transcripts involved in gluconeogenesis and altered glucokinase (GK) and hexokinase (HK) activities regardless of diet. However, growth rates did not reveal an impact of these responses. Adult zebrafish are unable to reform proportional representation within bacterial communities following transplantation of an allospecific biome resulting in transcriptional and enzymatic alterations for lipid and carbohydrate metabolism that did not affect overall animal homeostasis.
Project description:Prospecting of extreme microbial ecosystems associated to minerals (microbialites, microbial mats and endoevaporites) in Puna, Wetlands and Salars of Argentina, Chile and Bolivia
Project description:Interactions between microbial species are sometimes mediated by the exchange of small molecules, secreted by one species and metabolized by another. Both one-way (commensal) and two-way (mutualistic) interactions may contribute to complex networks of interdependencies. Understanding these interactions constitutes an open challenge in microbial ecology, with applications ranging from the human microbiome to environmental sustainability. In parallel to natural communities, it is possible to explore interactions in artificial microbial ecosystems, e.g. pairs of genetically engineered mutualistic strains. Here we computationally generate artificial microbial ecosystems without re-engineering the microbes themselves, but rather by predicting their growth on appropriately designed media. We use genome-scale stoichiometric models of metabolism to identify media that can sustain growth for a pair of species, but fail to do so for one or both individual species, thereby inducing putative symbiotic interactions. We first tested our approach on two previously studied mutualistic pairs, and on a pair of highly curated model organisms, showing that our algorithms successfully recapitulate known interactions, robustly predict new ones, and provide novel insight on exchanged molecules. We then applied our method to all possible pairs of seven microbial species, and found that it is always possible to identify putative media that induce commensalism or mutualism. Our analysis also suggests that symbiotic interactions may arise more readily through environmental fluctuations than genetic modifications. We envision that our approach will help generate microbe-microbe interaction maps useful for understanding microbial consortia dynamics and evolution, and for exploring the full potential of natural metabolic pathways for metabolic engineering applications.
Project description:Recent work with microbial communities has demonstrated an adaptive response to artificial selection at the level of the ecosystem. The reasons for this response and the level at which adaptation occurs are unclear: does selection act implicitly on traits of individual species, or are higher-level traits genuinely being selected? If the ecosystem response is just the additive combination of the responses of the constituent species, then the ecosystem response could be predicted a priori, and the ecosystem-level selection process is superfluous. However, if the ecosystem response results from ecological interactions among species, then selection at a higher level is necessary. Here we perform artificial ecosystem selection experiments on an individual-based evolutionary simulation model of microbial ecology and observe a similar response to that seen with real ecosystems. We demonstrate that a significant fraction of artificially selected ecosystem responses cannot be accounted for by implicit lower-level selection of a single type of organism within the community, and that interactions among different types of organism contribute significantly to the response in the majority of cases. However, when the ecological problem posed by the artificial ecosystem selection process can be easily solved by a single dominant species, it often is.
Project description:Functional profiles predicted based on taxonomic affiliations differed from those obtained by GeoChip microarray analysis, which separated community functional capacity based on plant location. The identified metabolic pathways provided insight regarding microbial strategies for colonization and survival in these ecosystems.
Project description:Glaciers are populated by a large number of microorganisms including bacteria, archaea and microeukaryotes. Several factors such as solar radiation, nutrient availability and water content greatly determine the diversity and abundance of these microbial populations, the type of metabolism and the biogeochemical cycles. In order to study their metabolic potentials, samples of glacial ice were taken from several glacial ecosystems. Microorganisms were analyzed by a polyphasic approach that combines a set of -omic techniques: 16S rRNA sequencing, culturomics and metaproteomics. This combination provides key information about diversity and functions of microbial populations, especially in rare habitats. Several whole essential proteins and enzymes related to metabolism and energy production, recombination and translation were found that demonstrate the existence of cellular activity at subzero temperatures.
Project description:Glaciers are populated by a large number of microorganisms including bacteria, archaea and microeukaryotes. Several factors such as solar radiation, nutrient availability and water content greatly determine the diversity and abundance of these microbial populations, the type of metabolism and the biogeochemical cycles. In order to study their metabolic potentials, samples of glacial ice were taken from several glacial ecosystems. Microorganisms were analyzed by a polyphasic approach that combines a set of -omic techniques: 16S rRNA sequencing, culturomics and metaproteomics. This combination provides key information about diversity and functions of microbial populations, especially in rare habitats. Several whole essential proteins and enzymes related to metabolism and energy production, recombination and translation were found that demonstrate the existence of cellular activity at subzero temperatures.
Project description:Microorganisms constitute a reservoir of enzymes involved in environmental carbon cycling and degradation of plant polysaccharides since they produce a vast variety of glycoside hydrolases. The CAZyChip was developed to allow a rapid characterization at transcriptomic level of these GHs and to identify enzymes acting on hydrolysis of polysaccharide or glycans. This DNA biochip contains the signature of 55,220 bacterial GHs available in the CAZy database. Probes were designed using two softwares and microarrays were directly synthetized using the in situ ink-jet technology. CAZyChip specificity and reproducibility was validated by hybridization of known GHs RNA extracted from recombinant E. coli strains, previously characterized by a functional metagenomic approach. The GHs arsenal was also studied in bioprocess conditions using rumen derived microbiota. The CAZyChip appears to be a user friendly tool for profiling the expression of a large variety of GHs. It can be used to study temporal variations of functional diversity, thereby facilitating the identification of new efficient candidates for enzymatic conversions from various ecosystems.
Project description:We report the (13)C content of preserved organic carbon for a 150 million-year section of late Archean shallow and deepwater sediments of the Hamersley Province in Western Australia. We find a (13)C enrichment of approximately 10 per thousand in organic carbon of post-2.7-billion-year-old shallow-water carbonate rocks relative to deepwater sediments. The shallow-water organic-carbon (13)C content has a 29 per thousand range in values (-57 to -28 per thousand), and it contrasts with the less variable but strongly (13)C-depleted (-40 to -45 per thousand) organic carbon in deepwater sediments. The (13)C enrichment likely represents microbial habitats not as strongly influenced by assimilation of methane or other (13)C-depleted substrates. We propose that continued oxidation of shallow settings favored the expansion of aerobic ecosystems and respiring organisms, and, as a result, isotopic signatures of preserved organic carbon in shallow settings approached that of photosynthetic biomass. Facies analysis of published carbon-isotopic records indicates that the Hamersley shallow-water signal may be representative of a late Archean global signature and that it preceded a similar, but delayed, (13)C enrichment of deepwater deposits. The data suggest that a global-scale expansion of oxygenated habitats accompanied the progression away from anaerobic ecosystems toward respiring microbial communities fueled by oxygenic photosynthesis before the oxygenation of the atmosphere after 2.45 billion years ago.
Project description:Despite the importance of microbial communities for ecosystem services and human welfare, the relationship between microbial diversity and multiple ecosystem functions and services (that is, multifunctionality) at the global scale has yet to be evaluated. Here we use two independent, large-scale databases with contrasting geographic coverage (from 78 global drylands and from 179 locations across Scotland, respectively), and report that soil microbial diversity positively relates to multifunctionality in terrestrial ecosystems. The direct positive effects of microbial diversity were maintained even when accounting simultaneously for multiple multifunctionality drivers (climate, soil abiotic factors and spatial predictors). Our findings provide empirical evidence that any loss in microbial diversity will likely reduce multifunctionality, negatively impacting the provision of services such as climate regulation, soil fertility and food and fibre production by terrestrial ecosystems.