Characterization of acidic endoglucanase Cel12A from Gloeophyllum trabeum and its synergistic effects on hydrogen peroxide–acetic acid (HPAC)-pretreated lignocellulose

Abstract

Gloeophyllum trabeum is a potent filamentous fungus that rapidly decomposes lignocellulose. In the present study, we cloned the G. trabeum cel12a gene and expressed it in Pichia pastoris strain GS115. The purified recombinant GtCel12A exhibited high pH stability and very high specific enzymic activity against β-glucan (6546 U mg−1) and carboxymethyl cellulose (1129 U mg−1) compared to GtCel5B, endoglucanases from Trichoderma reesei, and other glycoside hydrolase family 12 (GH12) enzymes. GtCel12A exhibited high enzymic activity with regard to hydrogen peroxide–acetic acid (HPAC)-pretreated lignocellulose biomass, and produced cellobiose as a major product with a small quantity of glucose. In combination with commercial cellulase, this enzyme also showed synergistic effects of 14.5, 16.1, 29.0, and 13.4% on filter paper, HPAC-pretreated pine, corn stover, and rice straw, respectively. The acidic endoglucanase GtCel12A from G. trabeum is a promising tool that can be used in combination with cellulase against HPAC-pretreated lignocellulose.