Document Type: Original Article


1 Department of Microbiology, Sciences and research branch, Islamic Azad University, Rasht Iran

2 Department of Microbiology, Faculty of Sciences, Islamic Azad University, Rasht Branch, Rasht, Iran

3 Department of Microbiology, Sciences and research branch, Islamic Azad University, Rasht, Iran


Objective: Investigations were carried out to isolate bacteria from saline-alkali soils and determined optimized alkaline protease activity and stability produced by a wild strain of bacillus sp. in submerged fermentation (SMF). Methods: Optimum temperature for enzyme activity in the crude extract was 40 ◦C at a pH between 8.0 and 9.0. The studies on pH stability showed that the enzyme was stable in a range of pH 7.0–10.0 and the effect of the inhibitors showed it to be possibly an alkaline protease. Stability studies revealed temperatures around 40–60 ◦C. Results: The activity was reduced in the presence of Co2+, Fe2+ and Zn2+ ions, while the presence of K+ resulted in a discreet increase in proteolytic activity. The enzyme presented good stability towards organic solvents. Organic solvents such as 2-ethyl-1-hexanol and oleyl alcohol enhanced the activity of enzyme. The enzyme presented good stability towards oxidizing agent. The crude enzyme preparation was compatible with commercial detergents, retaining their 50–60% activities. Conclusions: The results demonstrated the importance of submerged fermentation for the production of protease.


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