Fermentation of xylan by Clostridium acetobutylicum

Abstract

The ability of Clostridium acetobutylicum to utilize hemicelluloses as a substrate for butanol production was examined. Direct fermentation of byproduct corn fibres from the wet milling process showed complete utilization of starch and 20% utilization of hemicellulose with concurrent production of solvents and organic acids. Fermentations of isolated plant xylans were incomplete with 33–50% consumption of the carbohydrates and production of organic acids only. Hydrolysis of purified larchwood xylan by a concentrate of C. acetobutylicum fermentation broth revealed xylose is the major product of hydrolysis. The data suggest C. acetobutylicum primarily produces an exoxylanase, but not all the enzymes needed for complete hydrolysis of hemicellulose.