Abstract

Rakrudee Sarnthima¹ and Saranyu Khammuang²

DOI : http://dx.doi.org/10.13005/ojc/3404033

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 (CuSO₄) for laccase induction. Pretreatment the rice straw was performed by incubating laccase (2, 5, 10 U) with 10 g of rice straw in buffer at 40 and 50ºC for 24 h. 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 h. 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 higher level of reducing sugar than that of crude laccase without pretreatment. Rice straw hydrolyzed by 2 U of laccase at 40 and 50ºC 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.

Biomass; Cellulase; Laccase; Lignocellulose; Pretreatment

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