[Effect of Tween 80 and rhamnolipid on enzymatic hydrolysis of straw]

The method of enzymatic hydrolysis was adopted and straw was used as substrate to study the effects of reducing sugar yield, enzyme stability and convention rate of cellulose during the course of enzymatic hydrolysis as well as the impacts of enzyme kinetic characteristics and adsorption of cellulase on cellulose by addition of chemical-surfactant Tween 80 and biosurfactant rhamnolipid. The results indicated that Tween 80 and rhamnolipid at different concentrations enhanced the production of reducing sugar. Tween 80 at 0.016% and 0.048% increased reducing sugar yield by 18.07% and 11.98%, while rhamnolipid at 0.01% and 0.03% increased reducing sugar yield by 23.01% and 22.16%, respectively. It can be seen from the experimental results that surfactants improved enzyme stability availably. Surfactants at high concentrations were superior to those at low concentrations in enzyme stability. Tween 80 at 0.048% obtained maximal relative carboxymethylcellulose activity (CMCA) 108.06% and maximal relative filter paper activity (FPA) 80.26%. Surfactants also enhanced conversion rate of cellulose, and that in the present of rhamnolipid, the percent conversion of cellulose was higher than those with Tween 80 distinctly. Moreover, surfactants not only promoted maximal velocity of enzymatic reaction and largened Michaelis constant but also reduced adsorption of cellulase on cellulose remarkably.