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.
Highlights
200 billion tons of lignocellulose are produced every year
We studied the synergistic effects of GtCel12A with commercial cellulase on hydrogen peroxide–acetic acid (HPAC)-pretreated lignocellulose from pine, corn stover, and rice straw
The recombinant G. trabeum acidic endoglucanase Cel12A expressed by P. pastoris GS115 had an approximate molecular weight of 31 kDa, which differs from that of the enzyme expressed by A. niger
Summary
200 billion tons of lignocellulose are produced every year. These renewable polymers can be used to produce biofuel or biochemicals without competing with the first-generation feedstocks [1]. Enzymatic hydrolysis, which converts lignocellulose into its monomeric sugars, requires a hydrolytic enzyme complex [2]. A synergistic cooperation of cellulases, comprising exo-1,4-β-glucanases (EC 3.2.1.91 and EC 3.2.1.176) and endoglucanase (EC3.2.1.4), is important for the complete hydrolysis of lignocellulose. Endoglucanases, which hydrolyze the internal glucosidic bonds, provide exo-1,4-β-glucanases with new reducing and nonreducing ends. Enzymes have been widely used in the pulp and paper, textile, bioethanol, wine and brewery, food processing, animal feed, agricultural, biomolecular chemical
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