Alkaline Protease from Alkalotolerant Bacillus sp. B12 and Its Application in Detergent

Abstract

Thirty types of microorganisms were cultured in an alkaline soybean meal medium. The alkalotolerantBacillus sp. B12 was able to grow and produce the highest protease level. It is a Gram-variable, rod-shaped, sporeformingand oxygen required bacterium and produced catalase. Protease of the strain B12 was highly stable incommercial detergents such as P1, P2, L1, L2 and L3 when incubated at 50 ^oC for 1 hr. Bacillus sp. B12 couldgrow in the 0.5% soybean meal medium and produced high protease at pH 7.0 to 10.0. The most suitablecondition for alkaline protease production (0.44 Unit/ml) was pH 9.0 at 37 ^oC, and shaking at 250 rpm for 24 hr.Alkaline protease produced by this strain was found to increase along with the cell growth. The crude proteasehad an optimum pH from 8.0 to 11.0 and maintained its stability over a broad range of pH between 6.0 and 11.0for 1 hr. The optimum temperature for crude protease activity was from 30 to 80 ÌC. The protease was stablebetween 30 and 60 ^oC for 1 hr. To evaluate the protease action in improving the washing efficiency of thedetergents, the pieces of white cotton cloth soiled with cow blood stain were washed with L2 and L3 detergentsin the presence of the crude protease from Bacillus sp. B12. It showed the increases in bright values from 77.22and 71.73 to 80.24 and 75.83, respectively and the decreases in red values when compared to the washing onlywith detergents L2 and L3. Therefore, crude alkaline protease from Bacillus sp. 12 was a good candidate to beapplied in detergent industry.

Keywords : Alkaline Protease / Alkalotolerant Bacillus sp. / Detergent