Effect of Nitrogen Salts on Butanol and Hydrogen Production from Xylan by Using Clostridium Strain BOH3

Abstract

Clostridium strain BOH3 ferments 10g/l of xylan in reinforced clostridial medium (RCM) and produces butanol and hydrogen. However, increasing xylan concentration above 10g/l does not lead to higher concentrations of butanol and hydrogen. In this study, it shows that addition of ammonium sulfate to RCM can enhance cell density and the production of butanol and hydrogen. Based on response surface methodology (RSM), an optimized culture medium (OCM) was developed with 58.4g/l of xylan and 11.8g/l of ammonium sulfate to maximize butanol (12.15g/l) and hydrogen (3.29l/l) production. From RSM, butanol production depends on xylan concentration, whereas hydrogen production depends on ammonium sulfate concentration. Clostridium BOH3 in OCM also expresses 7.15U/ml of xylanase during fermentation, and the xylanase can be purified and recycled to further enhance the production of butanol and hydrogen.