Waste management and sustainable energy production are two major concerns of modern society. The use of microbial consortia for waste treatment has the potential to address both of these concerns simultaneously, since consortia possess the ability to convert crude biomass into biofuels and bio-based chemicals. The organic fraction of municipal solid waste (OFMSW) is an abundant and inexpensive carbon substrate that can be utilized by microbial systems to generate useful products. Anaerobic consortia containing fungi and methanogenic archaea capable of converting wet waste materials into valuable substances already exist in nature, and have been isolated from the guts of herbivores. Synthetic pairings of fungi and methanogens have been shown to accelerate biomass degradation while producing methane that can be captured and used as fuel. Although bioreactors utilizing undefined natural consortia to digest wet waste and generate biogas have been constructed, the failure rate is high due to consortia instability. The development of biotechnology capable of handling variable input, recovering from environmental disturbances, and producing consistent products is dependent upon engineering stability and robustness into the syntrophic relationship between consortia members. Here, we have used omics techniques to examine what drives stability in biomass-degrading anaerobic consortia. Growth curves were obtained for three synthetic pairings of the methanogen Methanobacterium bryantii with each of the anaerobic fungi Neocallimastix californiae, Caecomyces churrovis, and Piromyces finnis using pressure readings and gas chromatography. All pairings produced measurable amounts of methane when grown on a reed canary grass substrate. Methane production, a consistent indicator of growth that can be used as a metric to define longevity, ceased 14 days after inoculation for all pairings, indicating a distinct trend in consortia longevity. Metabolomics and transcriptomics were used to detect variations in metabolic output and gene expression for the synthetic pairings grown on different substrates in order to evaluate how variable inputs affect product consistency. The ability to engineer stability and robustness into biomass-degrading microbial communities capable of directly converting crude biomass into useful products will result in a reliable process that eliminates the costly, energy-intensive pretreatment step required by traditional bio-based production methods.

Engineering stable anaerobic consortia by understanding the genomic basis for syntrophic interactions

255th National Meeting (2018)

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