Project description:Marine microbial communities are critical for biogeochemical cycles and the productivity of ocean ecosystems. Primary productivity, at the base of marine food webs, is constrained by nutrient availability in the surface ocean, and nutrient advection from deeper waters can fuel photosynthesis. In this study, we compared the transcriptional responses by surface microbial communities after experimental deep water mixing to the transcriptional patterns of in situ microbial communities collected with high-resolution automated sampling during a bloom in the North Pacific Subtropical Gyre. Transcriptional responses were assayed with the MicroTOOLs (Microbiological Targets for Ocean Observing Laboratories) marine environmental microarray, which targets all three domains of life and viruses. The experiments showed that mixing of deep and surface waters substantially affects the transcription of photosystem and nutrient response genes among photosynthetic taxa within 24 hours, and that there are specific responses associated with the addition of deep water containing particles (organisms and detritus) compared to filtered deep water. In situ gene transcription was most similar to that in surface water experiments with deep water additions, showing that in situ populations were affected by mixing of nutrients at the six sampling sites. Together, these results show the value of targeted metatranscriptomes for assessing the physiological status of complex microbial communities.
Project description:The melting of permafrost and its potential impact on greenhouse gas emissions is a major concern in the context of global warming. The fate of the carbon trapped in permafrost will largely depend on soil physico-chemical characteristics, among which are the quality and quantity of organic matter, pH and water content, and on microbial community composition. In this study, we used microarrays and real-time PCR (qPCR) targeting 16S rRNA genes to characterize the bacterial communities in three different soil types representative of various Arctic settings. The microbiological data were linked to soil physico-chemical characteristics and CO2 production rates. Microarray results indicated that soil characteristics, and especially the soil pH, were important parameters in structuring the bacterial communities at the genera/species levels. Shifts in community structure were also visible at the phyla/class levels, with the soil CO2 production rate being positively correlated to the relative abundance of the Alphaproteobacteria, Bacteroidetes, and Betaproteobacteria. These results indicate that CO2 production in Arctic soils does not only depend on the environmental conditions, but also on the presence of specific groups of bacteria that have the capacity to actively degrade soil carbon.
Project description:The rate, timing, and mode of species dispersal is recognized as a key driver of the structure and function of communities of macroorganisms, and may be one ecological process that determines the diversity of microbiomes. Many previous studies have quantified the modes and mechanisms of bacterial motility using monocultures of a few model bacterial species. But most microbes live in multispecies microbial communities, where direct interactions between microbes may inhibit or facilitate dispersal through a number of physical (e.g., hydrodynamic) and biological (e.g., chemotaxis) mechanisms, which remain largely unexplored. Using cheese rinds as a model microbiome, we demonstrate that physical networks created by filamentous fungi can impact the extent of small-scale bacterial dispersal and can shape the composition of microbiomes. From the cheese rind of Saint Nectaire, we serendipitously observed the bacterium Serratia proteamaculans actively spreads on networks formed by the fungus Mucor. By experimentally recreating these pairwise interactions in the lab, we show that Serratia spreads on actively growing and previously established fungal networks. The extent of symbiotic dispersal is dependent on the fungal network: diffuse and fast-growing Mucor networks provide the greatest dispersal facilitation of the Serratia species, while dense and slow-growing Penicillium networks provide limited dispersal facilitation. Fungal-mediated dispersal occurs in closely related Serratia species isolated from other environments, suggesting that this bacterial-fungal interaction is widespread in nature. Both RNA-seq and transposon mutagenesis point to specific molecular mechanisms that play key roles in this bacterial-fungal interaction, including chitin utilization and flagellin biosynthesis. By manipulating the presence and type of fungal networks in multispecies communities, we provide the first evidence that fungal networks shape the composition of bacterial communities, with Mucor networks shifting experimental bacterial communities to complete dominance by motile Proteobacteria. Collectively, our work demonstrates that these strong biophysical interactions between bacterial and fungi can have community-level consequences and may be operating in many other microbiomes.
Project description:The melting of permafrost and its potential impact on greenhouse gas emissions is a major concern in the context of global warming. The fate of the carbon trapped in permafrost will largely depend on soil physico-chemical characteristics, among which are the quality and quantity of organic matter, pH and water content, and on microbial community composition. In this study, we used microarrays and real-time PCR (qPCR) targeting 16S rRNA genes to characterize the bacterial communities in three different soil types representative of various Arctic settings. The microbiological data were linked to soil physico-chemical characteristics and CO2 production rates. Microarray results indicated that soil characteristics, and especially the soil pH, were important parameters in structuring the bacterial communities at the genera/species levels. Shifts in community structure were also visible at the phyla/class levels, with the soil CO2 production rate being positively correlated to the relative abundance of the Alphaproteobacteria, Bacteroidetes, and Betaproteobacteria. These results indicate that CO2 production in Arctic soils does not only depend on the environmental conditions, but also on the presence of specific groups of bacteria that have the capacity to actively degrade soil carbon. Three different soil types from the Canadian high Arctic were sampled at two depths within the active layer of soil and at two sampling dates (winter and summer conditions), for a total of 20 samples.
Project description:Perfluoroalkyl acid carboxylates and sulfonates (PFAAs) have many consumer and industrial applications. The persistence and widespread distribution of these compounds in humans have brought them under intense scrutiny. Limited pharmacokinetic data is available in humans; however, human data exists for two communities with drinking water contaminated by PFAAs. Also, there is toxicological and pharmacokinetic data for monkeys, which can be quite useful for cross-species extrapolation to humans. The goal of this research was to develop a physiologically-based pharmacokinetic (PBPK) model for PFOA and PFOS for monkeys and then scale this model to humans in order to describe available human drinking water data. The monkey model simulations were consistent with available PK data for monkeys. The monkey model was then extrapolated to the human and then used to successfully simulate the data collected from residents of two communities exposed to PFOA in drinking water. Human PFOS data is minimal; however, using the half-life estimated from occupational exposure, our model exhibits reasonable agreement with the available human serum PFOS data. It is envisioned that our PBPK model will be useful in supporting human health risk assessments for PFOA and PFOS by aiding in understanding of human pharmacokinetics.
Model is encoded by Ruby and submitted to BioModels by Ahmad Zyoud
Project description:We report the sequencing of bacterial species across four environments in which C9orf72 loss of function mice were studied as well as mice that received fecal transplantation. Our study elucidates bacterial communities that associate with pro-inflammatory or pro-survival outcomes in this model of ALS/FTD with features of autoimmunity and systemic and neural inflammation.
Project description:Drought is one of the major environmental factors limiting biomass and seed yield production in agriculture. In this research we focused on plants from Fabaceae family, which have a unique ability for establishment of symbiosis with nitrogen-fixing bacteria, and are relatively susceptible to water limitation. We present the changes in nitrogenase activity and global gene expression occurring in Medicago truncatula and Lotus japonicus root nodules during water deficit. Our results prove a decrease in the efficiency of nitrogen fixation as well as extensive changes in plant and bacterial transcriptomes shortly after watering cessation. We show for the first time that not only symbiotic plant component, but also Sinorhizobium meliloti and Mesorhizobium loti bacteria residing in the root nodules of M. truncatula and L. japonicus, respectively, adjust their gene expression in response to water shortage. Although our results demonstrate that both M. truncatula and L. japonicus root nodules are susceptible to water deprivation, they indicate significant differences in plant and bacterial response to drought between tested species, which may be related to various type of root nodules formed by these species.
Project description:We have designed and experimentally validated the BactoChip, a 60-mer oligonucleotide microarray for simultaneous detection and quantification of multiple bacterial species of clinical interest. The Bactochip microarray targets a novel set of high-resolution marker genes, those genes that most unequivocally characterized each bacterial species. The accuracy of the BactoChip microarray was evaluated using the labeled total DNA of single bacterial species at different concentrations (from 65ng to more than 250ng). The specificity of the developed array was further validated using mixed cultures containing up to 15 different bacterial species in even or staggered amount. We employed the Agilent 'Custom HD-CGH 8x15k Array" (catalogue number: G4427A) and the Agilent'Genomic DNA ULS labeling Kit" (catalogue number: 5190-0419). The microarray successfully distinguished among bacterial species from 21 different genera. The BactoChip additionally proved accurate in determining species-level relative abundances over a 10-fold dynamic range in complex bacterial communities. In combination with the continually increasing number of sequenced bacterial genomes, future iterations of the technology could enable to highly accurate clinically-oriented tools for rapid assessment of bacterial community composition and relative abundances.
Project description:The increased urban pressures are often associated with specialization of microbial communities. Microbial communities being a critical player in the geochemical processes, makes it important to identify key environmental parameters that influence the community structure and its function.In this proect we study the influence of land use type and environmental parameters on the structure and function of microbial communities. The present study was conducted in an urban catchment, where the metal and pollutants levels are under allowable limits. The overall goal of this study is to understand the role of engineered physicochemical environment on the structure and function of microbial communities in urban storm-water canals.