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Published on Monday, 29 July 2013 Studying thermophillic microbes for better biofuel production The microbial world of biomass deconstruction became clearer with a JBEI/JGI/EMSL study of a thermophillic bacterial consortium adapted to switchgrass. This splatterplot is a visual representation of the consortium’s metagenome. (Image courtesy of Patrik D’haeseleer, JBEI) A recently concluded study on thermophiles – microbes that thrive at extremely high temperatures and alkaline conditions – could help determine the best microbial enzyme to break down biomass to extract fermentable sugars for advanced biofuels. Scientist from the United States Department of Energy’s Joint BioEnergy Institute and Joint Genome Insitute, the Environmental Molecular Sciences Laboratory and the Pacific Northwest National Laboratory worked on the project. They examined a compost-derived consortium of thermophillic bacterium adapted to grow on switchgrass. Using a combination of metagenomic and metaproteomic technologies, they identified individual microbial species whose enzymes were the most active in breaking down the switchgrass biomass. “This marks the first time that the functional roles of individual microbial populations within a consortium have been linked with specific enzyme activities, in this case cellulose and hemicellulose,” said Steven Singer, director of JBEI’s microbial communities program. Advanced biofuels are synthesized from the sugars in cellulosic biomass. These sugars such as cellulose and hemicellusose need to be extracted from lignin, the tough woody material that make up the plants cell wall and gives it structure and shape. Thermophilic microbes contain enzymes for lignocellulosic biomass deconstruction to get to cellulose and hemicelluloses without the use of pretreatment chemicals such as ionic liquids. “Using pretreated switchgrass at temperatures up to 80 degrees Celsius, we demonstrated that this consortium is an excellent source of enzymes for the development of enzymatic cocktails tailored to biorefinery processing conditions,” says Blake Simmons, a chemical engineer who heads JBEI’s Deconstruction Division and was a member of this research collaboration. They first used shotgun sequencing, a metagenomics technique that would enable them to determine the metabolic potential of all the members of the studied consortium. They then used metaproteomic measurements to identify those enzymes that were actually produced by the microbial community. Analysis of metagenomic sequencing data identified the most abundant microbial populations in the consortium to be closely related strains of Thermus thermophilus and Rhodothermus marinus. However, based on the assigned fractions of the switchgrass deconstruction proteome, the strains showing the most active role in switchgrass deconstruction were Gemmatimonadetes and Paenibacillus. By comparison, the more numerous Rhodothermus strain contributed fewer enzymes to biomass deconstruction. By gaining a more comprehensive understanding of how microbial consortia work to breakdown biomass and identifying the genes and enzymes involved, the scientist hope to be able to develop better processes for advanced biofuels. “The list of genes and enzymes generated by this study has been placed into our exp ression pipeline and are being used to develop optimized cocktails that are capable of generating high sugar yields from pretreated lignocellulosic biomass,” said Mr. Simmons. – EcoSeed Staff Continue reading →