Characterization of an alkalophilic extracellular chitosanase from Bacillus cereus GU-02

Abstract

An alkalophilic extracellular chitosanase (ACTase) was characterized from the culture supernatant of Bacillus cereus GU-02. Kinetic properties of ACTase produced from B. cereus GU-02 after cultivation in anaerobic condition, alkaline medium (pH 10) at 37 degrees C for 3 days were investigated. ACTase was found to be stable in alkaline pH range from 8 to 10. Interestingly, optimum pH and temperature were estimated to be 10 and 37 degrees C, respectively, where ACTase showed chitosan degrading activity (87%), which was enhanced by 15% in the presence of calcium ions (8 mM). The ACTase produced from B. cereus GU-02 was partially purified from the culture supernatant, and its enzymatic activity was kinetically characterized. The V-max and K-m were estimated with a chitosan (degree of deacetylation, DD 92% as substrate) as 0.038 U/min/mu g protein and 0327 mu M, respectively. A combination of the TIC and MALDI-TOF MS results showed that the chitosan oligosaccharides obtained from the hydrolysis of high molecular weight chitosan (HMWC) by ACTase of the B. cereus GU-2 comprise oligomers with degree of polymerization (DP) mainly from dimers to pentamers. High production of ACTase and chitooligosaccharides may be useful for various industrial and biological applications. (C) 2013, The Society for Biotechnology, Japan. All rights reserved.