Monday, April 30, 2012: 2:00 PM
Napoleon Ballroom A and B, 3rd fl (Sheraton New Orleans)
The recalcitrance of plant biomass remains a key obstacle in the development of consolidated bioprocessing (CBP) technologies for the production of cellulosic biofuels. Discovery of novel organisms, metabolic capabilities and functions will enhance our fundamental understanding of how CBP can be realized at the industrial scale. Our studies have enabled us to obtain novel cellulolytic microbial cultures from a variety of sites in nature, with a focus on anaerobic thermophilic clostridia. Given the predominance of Clostridium clariflavum strains in enrichments from various environments and the ability of these enrichments to utilize both cellulose and hemicellulose, we have sequenced the genome of the type strain (DSM 19732) and initiated comparative resequencing of our environmental strains. Analysis of the genome has provided us with a clearer picture of how these organisms access substrate by means of a unique cellulosomal system and multifunctional glycosyl hydrolases, many of them being novel xylanases. In addition, we have a better understanding of how these organisms process released sugars through alternative central metabolism pathways. Detailed fermentation experiments comparing the breakdown dynamics of xylan and xylooligomers among C. clariflavum strains and model organism C. thermocellum revealed distinctly different approaches to hemicellulose degradation and utilization. Likewise, fermentation dynamics of unpretreated switchgrass and glycome profiling of residual material point to untapped capabilities in plant cell wall solubilization and utilization. As a result, a combinatorial approach involving bioprospecting, fermentation science and genomic exploration has uncovered a variety of promising new microbial features comparable to other leading CBP models for cellulosic biomass conversion.