Effect and modeling of glucose inhibition and in situ glucose removal during enzymatic hydrolysis of pretreated wheat straw

Appl Biochem Biotechnol. 2010 Jan;160(1):280-97. doi: 10.1007/s12010-008-8512-9. Epub 2009 Jan 23.

Abstract

The enzymatic hydrolysis of lignocellulosic biomass is known to be product-inhibited by glucose. In this study, the effects on cellulolytic glucose yields of glucose inhibition and in situ glucose removal were examined and modeled during extended treatment of heat-pretreated wheat straw with the cellulolytic enzyme system, Celluclast 1.5 L, from Trichoderma reesei, supplemented with a beta-glucosidase, Novozym 188, from Aspergillus niger. Addition of glucose (0-40 g/L) significantly decreased the enzyme-catalyzed glucose formation rates and final glucose yields, in a dose-dependent manner, during 96 h of reaction. When glucose was removed by dialysis during the enzymatic hydrolysis, the cellulose conversion rates and glucose yields increased. In fact, with dialytic in situ glucose removal, the rate of enzyme-catalyzed glucose release during 48-72 h of reaction recovered from 20-40% to become approximately 70% of the rate recorded during 6-24 h of reaction. Although Michaelis-Menten kinetics do not suffice to model the kinetics of the complex multi-enzymatic degradation of cellulose, the data for the glucose inhibition were surprisingly well described by simple Michaelis-Menten inhibition models without great significance of the inhibition mechanism. Moreover, the experimental in situ removal of glucose could be simulated by a Michaelis-Menten inhibition model. The data provide an important base for design of novel reactors and operating regimes which include continuous product removal during enzymatic hydrolysis of lignocellulose.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aspergillus niger / enzymology
  • Biocatalysis / drug effects
  • Cellulose / metabolism
  • Enzymes / metabolism*
  • Glucose / isolation & purification*
  • Glucose / pharmacology*
  • Hydrolysis / drug effects
  • Kinetics
  • Models, Chemical*
  • Trichoderma / enzymology
  • Triticum / metabolism*

Substances

  • Enzymes
  • Cellulose
  • Glucose