Enhanced butanol production using Clostridium beijerinckii SE-2 from the waste of corn processing

Acetone-butanol-ethanol (ABE) fermentation from food processing waste is one way to reduce cost. In this study, corncob hydrolysate and corn steep liquor (CSL), two waste materials from corn processing industries, were used as carbon and nitrogen sources to yield butanol by using Clostridium beijerinckii SE-2. Media compositions favoring butanol production were investigated using statistical experimental designs. Media components were first screened using a fractional factorial experimental design. CSL and CH3COONH4 were found to be the significant variables among six factors, including the contents of CSL, CH3COONH4, K2HPO4-KH2PO4, MnSO4 center dot H2O, MgSO4 center dot 7H(2)O and FeSO4 center dot 7H(2)O. The two factors were further optimized by the steepest assent and central composite rotatable design. The validated experiments showed that the total ABE in the system was 19.22 g L-1 and the concentration of butanol could reach 11.65 g L-1 with the optimized medium, which was 42% higher than the initial medium. Scale-up fermentation with optimized medium in the 100 L bioreactor resulted in 20.29 g L-1 of ABE and 11.92 g L-1 of butanol. Moreover, C. beijerinckii SE-2 can use both glucose and xylose from corncob hydrolysate. In conclusion, our study suggested that the waste of the corn processing industry can be used as sources to produce butanol by Clostridium, and statistical experimental designs are a useful approach for optimizing media compositions for butanol production.