Project description:The ecological forces that govern the assembly and stability of the human gut microbiota remain unresolved. We developed a generalizable model-guided framework to predict higher-dimensional consortia from time-resolved measurements of lower-order assemblages. This method was employed to decipher microbial interactions in a diverse human gut microbiome synthetic community. We show that pairwise interactions are major drivers of multi-species community dynamics, as opposed to higher-order interactions. The inferred ecological network exhibits a high proportion of negative and frequent positive interactions. Ecological drivers and responsive recipient species were discovered in the network. Our model demonstrated that a prevalent positive and negative interaction topology enables robust coexistence by implementing a negative feedback loop that balances disparities in monospecies fitness levels. We show that negative interactions could generate history-dependent responses of initial species proportions that frequently do not originate from bistability. Measurements of extracellular metabolites illuminated the metabolic capabilities of monospecies and potential molecular basis of microbial interactions. In sum, these methods defined the ecological roles of major human-associated intestinal species and illuminated design principles of microbial communities.
Project description:Despite that most microorganisms live as part of community, we have modest knowledge about the interactions among microbial community members in nature, and the implications of those interactions for emergent community properties or ecosystem-relevant functions. To facilitate advances in understanding microbial interactions, we describe a straightforward synthetic community system for interrogating the extracellular interactions among microbial community members. The laboratory-scale system physically separates microbial populations within the community, but allows for chemical interactions via a shared media reservoir. Community goods, including small molecules, extracellular enzymes, and antibiotics, can be assayed using sensitive mass spectrometry, and community member outcomes can be assayed, for example, using flow cytometry, biomass measurements, and transcript analyses. The synthetic community design allows for determining the causes and consequences of community diversity and functional outcomes given manipulation of community membership or structure, abiotic stressors, or temporal dynamics. Because it is versatile to accommodate any artificial or environmental microbiome members, scalable to high-throughput capacity, flexible to an array of experimental designs, and accessible to a variety of laboratories because no specialized or costly components are required, this synthetic community system has the potential to practically advance knowledge of microbial interactions within both natural and artificial communities.
Project description:Microbial communities colonize plant tissues and contribute to host function. How these communities form and how individual members contribute to shaping the microbial community are not well understood. Synthetic microbial communities, where defined individual isolates are combined, can serve as valuable model systems for uncovering the organizational principles of communities. Using genome-defined organisms, systematic analysis by computationally-based network reconstruction can lead to mechanistic insights and the metabolic interactions between species. In this study, 10 bacterial strains isolated from the Populus deltoides rhizosphere were combined and passaged in two different media environments to form a stable microbial community. The membership and relative abundances of the strains stabilized after around 5 growth cycles and resulted in just a few dominant strains. To unravel the underlying metabolic interactions, the KBase platform was used for constructing community-level models and for elucidating the metabolic processes involved in shaping the microbial communities. These analyses were complemented by growth curves of the individual isolates, pairwise interaction screens, and metaproteomics of the community. Flux balance analysis was used to model the metabolic potential in the microbial community and identify potential metabolic exchanges among the component species. Revealing the mechanisms of interaction among plant-associated microorganisms will provide insights into strategies for engineering microbial communities that can potentially increase plant growth and disease resistance. Further, deciphering the membership and metabolic potentials of a bacterial community will enable the design of synthetic co-cultures with desired biological functions.
Project description:Though most microorganisms live within a community, we have modest knowledge about microbial interactions and their implications for community properties and ecosystem functions. To advance understanding of microbial interactions, we describe a straightforward synthetic community system that can be used to interrogate exometabolite interactions among microorganisms. The filter plate system (also known as the Transwell system) physically separates microbial populations, but allows for chemical interactions via a shared medium reservoir. Exometabolites, including small molecules, extracellular enzymes, and antibiotics, are assayed from the reservoir using sensitive mass spectrometry. Community member outcomes, such as growth, productivity, and gene regulation, can be determined using flow cytometry, biomass measurements, and transcript analyses, respectively. The synthetic community design allows for determination of the consequences of microbiome diversity for emergent community properties and for functional changes over time or after perturbation. Because it is versatile, scalable, and accessible, this synthetic community system has the potential to practically advance knowledge of microbial interactions that occur within both natural and artificial communities. See publications: https://journals.asm.org/doi/10.1128/mSystems.00129-17 and https://journals.asm.org/doi/10.1128/mSystems.00493-20 and https://www.biorxiv.org/content/10.1101/2021.09.05.459016v2.full.
The work (proposal:https://doi.org/10.46936/10.25585/60000724) conducted by the U.S. Department of Energy Joint Genome Institute (https://ror.org/04xm1d337), a DOE Office of Science User Facility, is supported by the Office of Science of the U.S. Department of Energy operated under Contract No. DE-AC02-05CH11231.
Project description:16S amplicon pool analyses of the four gut sections of the wood-feeding beetle, Odontotaenius disjunctus The beetle is purely wood feeding, and we aim to first characterize the community that exist within the gut sections 4 beetles, four gut sections per beetle, one PhyloChip per gut section, total = 16 chips
Project description:Composition of the gut microbiome is influenced by diet. Milk or formula oligosaccharides act as prebiotics, bioactives that promote the growth of beneficial gut microbes. The influence of prebiotics on microbial interactions is not well understood. Here we investigated the transformation of prebiotics by a consortium of four representative species of the infant gut microbiome, and how their interactions changed with dietary substrates. First, we optimized a culture medium resembling certain infant gut parameters. A consortium containing Bifidobacterium longum subsp. infantis, Bacteroides vulgatus, Escherichia coli and Lactobacillus acidophilus was grown on fructooligosaccharides (FOS) or 2'-fucosyllactose (2FL) in mono- or co-culture. While Bi. infantis and Ba. vulgatus dominated growth on 2FL, their combined growth was reduced. Besides, interaction coefficients indicated strong competition, especially on FOS. While FOS was rapidly consumed by the consortium, B. infantis was the only microbe displaying significant consumption of 2FL. Acid production by the consortium resembled the metabolism of microorganisms dominating growth in each substrate. Finally, the consortium was tested in a bioreactor, observing similar predominance but more pronounced acid production and substrate consumption. This study indicates that the chemical nature of prebiotics modulate microbial interactions in a consortium of infant gut species.