1-50: Physiology of hemicellulose degradation and genomic exploration of the cellulolytic thermophile Clostridium clariflavum

Clostridium clariflavum is a thermophilic anaerobe able to utilize a variety of cellulosic substrates.  Our group has recently characterized cellulolytic enrichments from thermophilic compost dominated by C. clariflavum strains.  Given their predominance in these consortia and the ability of these enrichments to utilize xylan, we have sequenced the genome of the type strain to further understand this organism. A total of 72 glycosyl hydrolases have been identified in the genome, most of which have their closest match in C. thermocellum, its closest sequenced relative. However, the number and diversity of xylanases present in the C. clariflavum genome is much higher, as is the number of enzymes involved in 5-carbon sugar metabolism. Comparison of xylan, xylodextrin and xylose breakdown dynamics among C. clariflavum strains and C. thermocellum revealed very different approaches to xylan degradation and subsequent utilization. Expanding our understanding of the physiological features of C. clariflavum provides insights into novel approaches for cellulolytic clostridia to break down cellulose, hemicellulose and other components of woody plant biomass.