Isolation and Screening of Protease Producing Bacteria from Local Environment for Detergent Additive

Abstract

Proteases are among the most important hydrolytic enzymes that found in every organism to undertake important physiological functions. They are multipurpose enzymes used in various industries such as detergent, silver recovery, food, pharmaceutical, leather, and textile industries. This work aimed to produce protease from indigenous microbes for use as detergent additive. Isolation of protease producer was undertaken using skim milk agar medium. Crude enzyme was characterized in terms of wash and stain removal tests. A total of 188 protease positive bacteria were isolated from seven samples collected from Arba Minch town. Out of 36 alkaline protease producing bacteria, one isolate designated as Bacillus sp. Cab44 was selected. The optimum activity was reached at pH 9 and 50°C. The enzyme was stable in the pH range of 7 to 10. It retained 75%, 86% and 72% activity after one hr pre-incubation at 50°C, in 15% H2O2 and 0.3% commercial detergent respectively. The enzyme activity was increased by Mg2+, Cu2+, and Mn2+, was not affected by Ca2+ but decreased by Zn2+, Hg2+ and Fe2+. It removed stains of blood and egg yolk on cotton cloth at pH 9, 40°C, 5.07 U/ml in 30-40 min. These properties suggest that protease from Bacillus sp. Cab44 could find potential application in detergent industries as good candidate of additive in detergent formulation which have economic implication.