Recombinant expression and characterization of a novel endoglucanase from Bacillus subtilis in Escherichia coli

Abstract

The goal of this work was to produce high levels of endoglucanase in Escherichia coli for its potential usage in different industrial applications. Endoglucanase gene was amplified from genomic DNA of Bacillus subtilis JS2004 by PCR. The isolated putative endoglucanase gene consisted of an open reading frame of 1,701 nucleotides and encoded a protein of 567 amino acids with a molecular mass of 63-kDa. The gene was cloned into pET-28a(+) and expressed in E. coli BL21 (DE3). Optimum temperature and pH of the recombinant endoglucanase were 50 °C and 9, respectively which makes it very attractive for using in bio-bleaching and pulp industry. It had a K M of 1.76 μmol and V max 0.20 μmol/min with carboxymethylcellulose as substrate. The activity of recombinant endoglucanse was enhanced by Mg2+, Ca2+, isopropanol and Tween 20 and inhibited by Hg2+, Zn2+, Cu2+, Ni2+ and SDS. The activity of this recombinant endoglucanase was significantly higher than wild type. Therefore, this recombinant enzyme has potential for many industrial applications involving biomass conversions, due to characteristic of broad pH and higher temperature stability.