Inhibition of cellulase, β‐glucosidase, and xylanase activities and enzymatic hydrolysis of dilute acid pretreated wheat straw by acetone‐butanol‐ethanol fermentation products

Abstract

Simultaneous saccharification and fermentation has been regarded as a promising process for bioconversion of lignocellulosic biomass to acetone‐butanol‐ethanol (ABE); however, there exits potential inhibition of cellulase, β‐glucosidase, and xylanase by the fermentation product(s) due to the combination of enzymatic hydrolysis and microbial fermentation in one vessel. The effects of ABE fermentation products including acetone, butanol, ethanol, acetic acid, and butyric acid, individually and in a combination, on the cellulase, β‐glucosidase, and xylanase activities and enzymatic saccharification of dilute acid pretreated wheat straw (WS) were studied. The experimental results showed that butanol and mixture of inhibitor compounds strongly depressed cellulolytic and hemicellulolytic activities, and no synergistic inhibiting effect between inhibitors on enzyme activities was observed. Saccharification of pretreated WS was mainly affected by butanol and temperature. Moreover, preincubation of enzyme solutions with inhibitors mixture for 72 h decreased cellulase and xylanase activities by 15–25% at the three temperatures examined (30, 37, and 50°C), and a significant decrease (64%) in β‐glucosidase activity was found at 50°C. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 497–503, 2014