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Chemistry and Industry of Forest Products ›› 2016, Vol. 36 ›› Issue (4): 7-13.doi: 10.3969/j.issn.0253-2417.2016.04.002

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Evaluation of the Factors Contributing to Declining Enzymatic Hydrolysis Rates of Steam Pretreated Corn Stover

LAI Chen-huan, YANG Lei, GAO Zi-qi, YU Shi-yuan, YONG Qiang   

  1. College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China
  • Received:2015-09-01 Online:2016-08-25 Published:2016-09-01

Abstract: To evaluate the factors contributing to the decreasing enzymatic hydrolysis rates, the potential factors, including substrate reactivity, enzyme non-productive binding, enzyme deactivation and end-product inhibition, were investigated in enzymatic hydrolysis of steam pretreated corn stover (SPCS), with solid concentration of 50 g/L glucan and enzyme loading including 20 FPIU/g glucan of filter paper activity and 10 IU/g glucan of β-glucosidase activity. The results showed that the substrate reactivity of SPCS decreased 16.0% and 23.7%, respectively, after hydrolysis for 6 h and 12 h. But the effects of the decline in substrate reactivity on enzymatic hydrolysis rates were limited, with enzyme loading including 20 FPIU/g glucan of filter paper activity and 10 IU/g glucan of β-glucosidase activity. The enzymatic residual lignin addition reduced the enzyme concentration in supernatant by 20.8% at 1 h, but this did not reduce the initial hydrolysis rates. This indicated that enzyme non-productive binding on lignin did not influence the enzymatic hydrolysis rates obviously. Enzyme renewal in two-stage hydrolysis increased hydrolysis rate for 7 h from 1.30 g/(L·h) in one-stage hydrolysis to 1.83 g/(L·h). While the end-product removal in two-stage hydrolysis raised hydrolysis rate for 7 h to 4.76 g/(L·h), which was 3.66 folds higher than that in one-stage hydrolysis. Generally, the results revealed that the enzyme deactivation and the end-product inhibition showed the obvious effects on enzymatic hydrolysis rates. Moreover, the end-product inhibition was the dominating factors for the declining hydrolysis rates of SPCS.

Key words: corn stover, steam pretreatment, enzymatic hydrolysis rate, substrate reactivity, end-product inhibition

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