Laccase from Lentinus polychrous Increases the Efficiency of Cellulose Hydrolysis of Rice Straw to Glucose

Abstract

This study investigated the pretreatment of rice straw by crude laccase from Lentinus polychrous for preparation of lignocellulosic materials prior to be hydrolysed with cellulase for obtaining reducing sugar. Production of laccase involved cultivation of L. polychrous on solid media containing rice bran and rice husk supplemented with copper sulfate Pretreatment the rice straw was performed by incubating laccase (2, 5, 10 U) with 10 g of rice straw in buffer at 40 and 50 o C for 24 hours. Then the rice straw was analyzed by fourier transform infrared spectroscopy (FT-IR). Laccase-pretreated rice straws were further hydrolyzed by commercial cellulase from Trichoderma reesei at activity of 0, 10, 20, 30 Filter Paper Unit (FPU) for 24 hours. Then reducing sugar was extracted and determined by the dinitrosalicylic acid (DNS) method. It was found that the rice straw pretreated with crude laccase gave a higher level of reducing sugar than that of crude laccase pretreatment. Rice straw hydrolyzed by 2 U of laccase at 40 and 50 o C yielded the highest reducing sugar at every cellulase activity used (10, 20 and 30 FPU). The results showed that crude laccase could be applied to increase the efficiency of lignocellulose hydrolysis by cellulase.

Pre-treatments applied to rice husk enzymatic hydrolysis: effect on structure, lignocellulosic components, and glucose production kinetics

“…Similar results were reported after freezing pre-treatments that increased the rice husk from 48% to 84% Chang, Thitikorn-amorn [9], León, German [10]. However, the obtained glucose yield was higher compared to the obtained after rice husk pre-treatments with Laccase from Lentinus polychrous [11] or after high-pressure microwave [30].…”

“…Some pret-reatments have been studied to modify the structure and composition of lignocellulosic sources from residues. Using rice husk, it was studied freezing pre-treatment [9] and alkaline pre-treatment [10], pre-treatments with laccase from Lentinus polychrous [11], in all cases the enzymatic digestibility was increased. On the other hand, mechanical fractionation pre-treatments at different levels were applied in corn cobs [12]; cellobiose, cellulase and NaOH in pineapple stubble [13]; H2O2, H2SO4 and NaOH in cassava residues [14]; steam explosion, acid and alkaline pre-treatment in pine sawdust [15].…”