Characterisation of a novel Bacillus sp. SJ-10 β-1,3-1,4-glucanase isolated from jeotgal, a traditional Korean fermented fish.

A novel β-1,3-1,4-glucanase gene was identified in Bacillus sp. SJ-10 (KCCM 90078) isolated from jeotgal, a traditional Korean fermented fish. We analysed the β-1,3-1,4-glucanase gene sequence and examined the recombinant enzyme. The open reading frame of the gene encoded 244 amino acids. The sequence was not identical to any β-glucanases deposited in GenBank. The gene was cloned into pET22b(+) and expressed in Escherichia coli BL21. Purification of recombinant β-1,3-1,4-glucanase was conducted by affinity chromatography using a Ni-NTA column. Enzyme specificity of β-1,3-1,4-glucanase was confirmed based on substrate specificity. The optimal temperature and pH of the purified enzyme towards barley β-glucan were 50 °C and pH 6, respectively. More than 80 % of activity was retained at temperatures of 30-70 °C and pH values of 4-9, which differed from all other bacterial β-1,3-1,4-glucanases. The degradation products of barley β-glucan by β-1,3-1,4-glucanase were analysed using thin-layer chromatography, and ultimately glucose was produced by treatment with cellobiase.