The Research On The Effect Of Surfactants On Enzymatic Hydrolysis Of Straw

Making use of renewable lignocellulose to produce alcohol is a source of alternative energy resource instead of petroleum.Transforming lignocellulose to alcohol contains hydrolyzing to produce reducing sugar and fermenting reducing sugar to produce alcohol, and hydrolyzing is the key step. Using cellulase to accelerate hydrolysis and promoting the activity of cellulase and the hydrolysis yield had been focused on widely at the present time.The method of enzymatic hydrolysis was adopted and straw pretreated by diluted vitriol was used as substrate to study the effects of reducing sugar yield, enzyme stability, surface tension 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 1cmc and 3cmc increased reducing sugar yield by 18.07% and 11.98%, while rhamnolipid at 1cmc and 3cmc 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 3cmc obtained maximal relative CMCA(Sodium carboxymethylcellulose activity)108.06% and maximal relative FPA(Filter paper activity)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.This experience also studied the impacts of reducing sugar yield and protein concentration by renewal straw alone as well as renewal both of straw and surfactants during enzymatic hydrolysis process. The results of this research indicated that the renewable of straw during enzymatic hydrolysis enhanced both reducing sugar yield and protein concentration. Rhamnolipid had higher reducing sugar yield than Tween 80, and rhamnolipid at 3cmc had the best effect. The protein concentration also increased along with enzymatic hydrolysis and rhamnolipid enhanced protein concentration most evidently. Rhamnolipid at 1cmc and 3cmc promoted protein concentration by 75.44% and 77.33% respectively. In renewable both of straw and surfactants enzymatic system, Tween 80 at 3cmc promoted reducing sugar yield by 22.71%, while rhamnolipid at 1cmc enhanced reducing sugar yield by 11.96%. Tween 80 and rhamnolipid enhanced protein concentration notabely. Tween 80 at 3cmc and 1cmc increased protein concentration by 94.38% and 76.07%, while rhamnolipid raised the protein concentration more than 80%.