Partial purification and characterization of metalloprotease of halotolerant alkaliphilic bacterium Bacillus cereus from coastal sediment of Goa, India

We partially purified extracellular metalloprotease of a halotolerant alkaliphilic bacterium isolated from coastal sediment of Goa, India, which was identified as Bacillus cereus strain CS1 based on biochemical characteristics and 16S rDNA sequence. Zymogram of partially purified enzyme clearly revealed two prominent protease isozymes of 210 and 215 kDa. Although, protease showed activity over a wide range of pH (pH 8 to 12) and temperature (30, 37, 45 and 50°C), optimum pH and temperature were 9 and 37°C, respectively. Protease exhibited extreme halotolerance upto 8% NaCl making it one of the industrially valuable enzyme. Among different carbon sources, glucose (1%) enhanced maximum enzyme activity (71U/ml), whereas, among the nitrogen sources, tryptone (0.2%) proved best to enhance enzyme activity (158U/ml). Ca++ ions enhanced protease activity by 7%, whereas, Cu++, Mg++, Pb++ and Hg++ ions inhibited activity by 91, 79, 87 and 77%, respectively. Among inhibitors tested, protease activity was significantly inhibited by Na2–EDTA as residual enzyme activity was only 21%, which clearly confirmed it to be a metalloprotease. The partially purified protease mixed separately with two detergents Rin and Wheel clearly demonstrated significant stain removing capability. Thus, protease produced by Bacillus is a potential candidate as an additive in detergent industry.Keywords: Halo-tolerant, isozymes, zymogram, metalloprotease.African Journal of Biotechnology Vol. 12(31), pp. 4905-491

Biotransformation of Tributyltin chloride by Pseudomonas stutzeri strain DN2

A bacterial isolate capable of utilizing tributyltin chloride (TBTCl) as sole carbon source was isolated from estuarine sediments of west coast of India and identified as Pseudomonas stutzeri based on biochemical tests and Fatty acid methyl ester (FAME) analysis. This isolate was designated as strain DN2. Although this bacterial isolate could resist up to 3 mM TBTCl level, it showed maximum growth at 2 mM TBTCl in mineral salt medium (MSM). Pseudomonas stutzeri DN2 exposed to 2 mM TBTCl revealed significant alteration in cell morphology as elongation and shrinkage in cell size along with roughness of cell surface. FTIR and NMR analysis of TBTCl degradation product extracted using chloroform and purified using column chromatography clearly revealed biotransformation of TBTCl into Dibutyltin dichloride (DBTCl2) through debutylation process. Therefore, Pseudomonas stutzeri strain DN2 may be used as a potential bacterial strain for bioremediation of TBTCl contaminated aquatic environmental sites