Heterologous expression and characterization of detergent stable endoglucanase EG5B from Paenibacillus sp. IHB B 3084

Abstract

The endoglucanase gene EG5B of 1611bp with a predicted molecular weight of 58.6kDa from Paenibacillus sp. IHB B 3084 was cloned and expressed in Escherichia coli BL21(DE3). The analysis of deduced amino acid sequence revealed a modular structure of the endoglucanase EG5B with an N-terminal catalytic domain of glycosyl hydrolase family 5 and a C-terminal carbohydrate-binding module of family 3. The purified enzyme showed high hydrolytic activity on carboxymethylcellulose, low activity on p-nitrophenyl β-d-cellobioside, avicel and filter paper, and no activity on microcrystalline cellulose, p-nitrophenyl β-d-glucoside, cellobiose and salicin as substrates. The enzyme was mild-alkaline active with optimum activity at pH 7–8 and stable over broad pH range. The temperature optimum was at 50°C with >50% activity over 30–60°C. The enzyme stability with >63% residual activity towards non-ionic and anionic surfactants and commercial detergents suggested its compatibility as an additive to detergents.