Characterization of bacillus cereus BM1 with protease activity

Abstract

Microbial alkaline proteases dominate the world enzyme market, accounting fornearly two-thirds shares of the detergent industry. To date, Bacillus species have beenknown to produce a substantial amount of extracellular proteases which gain applicationin commercial industry. A protease producing bacterium was isolated from the eye of seabass, for the first time, in an attempt to search for microbial biocatalyst that is detergentcompatible. The isolate was characterized based on 16S rRNA gene sequence homologyand Biolog Gen III microplate system. The results for identification indicate that theisolate has 97% sequence identity to Bacillus cereus with regard to 16S rRNA genesequence homology which ultimately tally with the result of Biolog system, and hencedesignated as Bacillus cereus BM1. Moreover, protease produced by the isolate BM1 wasassayed according to an established method. Subsequently the protease was partiallycharacterized on the basis of temperature and pH requirements. Further characterizationevaluated the effects of different metal ions (5mM), EDTA (5mM), NaCl (Up to 15%w/v)and commercial detergent (up to 10%w/v) on protease activity and/or stability. The resultsindicate that the Bacillus cereus BM1 produced a protease that is stable in alkaline pHrange of 8-12, with optimum at pH 8 when incubated at 60 o C for 1 hr. The protease wasalso stable at temperature ranges from 40-70 o C, with optimum at 60 o C when incubated for1 hr. It shows activity in the presence of EDTA, as metal chelator suggesting that it is nota metalloprotease. Furthermore, none of the metal ions tested enhances protease activityabove 100% from the control. The protease was also found to be stable in the presence ofNaCl and commercial detergent. The results of partial characterization of the enzymeindicate that it is an alkaline, thermostable, halotolerant and detergent compatible nonmetalloprotease. This suggests that it will find application in detergent industry.