Production of protease by bacillus sp. N-40 isolated from soil and its enzymatic properties

Abstract

Fifty four Bacillus strains isolated from different soils were screened for protease production. One strain producing maximum protease was selected. In order to enhance the production of protease, the effects of major medium ingredients, such as carbon, nitrogen sources and metal ions, on the production of the enzyme were investigated. Among the carbon sources used, fructose showed the highest potential for the production. The best organic nitrogen source was skim milk. Inorganic nitrogen sources were not as effective as organic sources. Addition of combine metal ions minimized the enzyme production. Combinations of Ca2+ and Mg2+ in medium were the best. Both ions were not effective alone. Increased production (51%) of the enyzme was obtained by manipulating the medium composition. The optimum pH and temperature for the purified enzyme activity were 7.0 and 55°C, respectively. The study of its stability showed that the enzyme is stable in the alkaline pH range 6.0-9.0, and at temperatures between 40 and 70 °C. The enzyme was also thermostable (77% at 55 °C for 3 h). The enzyme activity was stimulated by Mn2+ and Ca2+. It showed a single band with a molecular weight of 52 kDA by SDS-PAGE.