Purification and characterization of a novel extracellular β-1,3-glucanase produced byBacillus clausii NM-1 isolated from ezo abaloneHaliotis discus hannai

Abstract

A novel extracellular alkaline stable β-1,3-glucanase produced byBacillus clausii NM-1 isolated from the ezo abaloneHaliotis discus hannai was purified by ammonium sulfate precipitation, DEAE-Sepharose FF ion exchange chromatography and Sephacryl S-200HR gel filtration. The molecular weight of the purified enzyme was estimated to be 71 kDa from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme was very stable at pH 5.3 to 11.5 but unstable at pH 4.0 to 4.5. The optimum temperature and thermostability of the enzyme increased in the presence of CaC1, The enzyme hydrolyzed R-1,3-glucan from marine organisms, but did not show activity against any other β-1,3-glucans. The major hydrolysis products of β-1,3-glucan fromLaminaria digitata andEisenia bicyclis were laminaritriose and laminaritetraose, respectively. The N-terminal amino acid sequence of the purified enzyme was similar to that of several β-1,3-glucanases in the glycoside hydrolase family 16.