Biology Department Seminar

Biological production of liquid fuels derived by microbially-mediated conversion of biomass is rapidly becoming a key mechanism for meeting the global demand for alternate fuels. Fermentative Clostridia species are particularly desirable for such processes due to their ability rapidly degrade recalcitrant biomass, to efficiently ferment hexose and pentose sugars to ethanol and higher quality liquid fuels, and/or to directly convert synthesis gases such as CO2 and H2 to liquid fuels. To expand the genomic knowledge base of biofuels-relevant species, we have sequenced the genomes of 20+ Clostridia strains associated with biomass conversion, syngas fermentation, sugar fermentation and biofuels production. This increases the number of available Clostridia genomes to 150+ allowing for the first in-depth genome-scale analysis of the class. This dataset includes 8 species that employ extracellular membrane-bound cellulosome complexes for degrading cellulolosic materials. Analysis of the cellulosome component composition among these strains reveals a high diversity and large distribution of cellulosome genes across multiple lineages. This diversity is attributed largely to a high level of domain swapping and lateral gene transfer within and between lineages. The Clostridia sequencing project also expands the number of saccharolytic Thermoanaerobacter species to 16. Thermoanaerobacter species efficiently ferment both hexose and pentose (particularly xylose) sugars to ethanol at high yields. In co culture with select Clostridium thermocellum strains, Thermoanaerobacter promotes rapid biomass degradation and increased ethanol yields. Genomic, experimental and transcriptomics analysis were conducted to link the phenotypes of different Thermoanaerobacter strains to genomic characteristics and to determine what factors most influence ethanol yields.