Clostridium phytofermentans is an anaerobic ethanol- and hydrogen-producing cellulolytic bacterium from forest soil that is capable of fermenting all major carbohydrate components of biomass. It grows optimally at 35-37 degrees Celsius. Cells stain Gram-negative, despite having a Gram-positive cell-wall ultrastructure, and are motile, straight rods that form spherical terminal spores that swollen with sporangium. Cellulose, pectin, starch, and xylan are rapidly degraded and fermented with ethanol, acetate, CO2 and H2 as the major end-products and formate and lactate as minor products. Two to 4 times more ethanol than acetate are formed, suggesting that C. phytofermentans possesses unusual fermentation pathways. Hydrogen production approaches maximum amounts expected based on the amounts of non-gaseous products formed, thus it is interesting from a biotechnology point of view. Phylogenetically, C. phytofermentans is a member of Cluster XIVa of the low-G+C-content Gram-positive bacteria, only distantly related to another cellulose-degrading bacterium, Clostridium thermocellum (CLOTH) (adapted from genome.jgi-psf.org/finished_microbes/clopi/clopi.home.html).