Production and characterization of protease from halophilic virgibacillus species CD6

Abstract

In enzyme production industries, the major challenges that hinder the efficient and economic commercial scale application of proteases are their stability in broad range of pH, temperature, salinity, as well as their optimal activity in the presence of metal ions, organic solvents and detergents. Moreover, the enzyme purification steps also contribute to the cost of production. To overcome this problem, characterization and production of crude protease with attractive properties from wild bacterial isolate could be an alternative as it is a more cost-effective way compared to production of protease that involves purification steps and protein engineering approach. Therefore, crude protease of Virgibacillus sp. CD6 isolated from salted-fish was characterized in this study using azocasein assay and bioinformatics tools. Protease production was found to be highest when using soybean meal and yeast extract as nitrogen source compared to other organic nitrogen sources. The protease exhibited vast range of stability with optimum activity at 10.0 % (w/v) NaCl, 60ºC, pH 7 and 10, indicating its polyextremophilicity. The enzyme activity was enhanced by Mg2+, Mn2+, Cd2+ and Al3+. Both PMSF and EDTA hindered protease activity, denoting the presence of serine protease and metalloprotease properties respectively. High protease stability (>80%) was demonstrated in presence of organic solvents and detergent constituents investigated, and surprisingly it is exceptionally compatible with commercial detergents. Phylogenetic analyses revealed that proteases of Virgibacillus sp. demonstrated far distance relationship with other species, which worth for further exploration. Attributes of this protease can actualize necessity of searching superlative enzymes from extremophiles for diverse applications, particularly in detergent industry.