Purification and characterization of an extracellular thermo-alkali stable, metal tolerant chitinase from Streptomyces chilikensis RC1830 isolated from a brackish water lake sediment

摘要

An extracellular thermo-alkali stable chitinase was obtained from Streptomyces chilikensis RC1830, a novel actinobacterial strain isolated from the sediments of Chilika lake, India. Purification of the enzyme was carried out by concentrating the enzyme with centrifugal device followed by chromatographic separation by DEAE Sepharose ion exchange resin.The molecular weight of the enzyme was 10.5 kDa as determined by SDS-PAGE. The optimum pH and temperature for the partially purified chitinase was pH 7 and 60 °C. The chitinase showed 40% activity at pH 11 after 24 h exposure at room temperature. The chitinase exhibited Km and Vmax values are 0.02 mM and 3.184 mol/min/mg of enzyme respectively. The 6 residue N-terminal sequence of the enzyme was not found similar to any of the reported chitinase enzyme. Based on the SDS PAGE, zymogram analysis, activity assays and other characteristics, it is proposed that the purified enzyme from S.chilikensis RC1830 is a chitinase. Keywords: Streptomyces, Chitinase, Halo tolerant, Chio oligosaccharides