Influence of process parameters on the production of detergent compatible alkaline protease by a newly isolated Bacillus sp. Y.

Abstract

Detergent compatible alkaline protease production by a newly isolated Bacillus sp.Y from laundry soil was studied under shake flask conditions in growth medium comprised (g/L): peptone, 1; NaCl, 5; skim milk, 100; Na_2CO_3, 4. Different environmental process parameters such as fermentation period, initial pH, incubation temperature, and nutritional parameters such as supplementation of different starch sources and nitrogen sources were standardized for the maximum yield of alkaline protease. Rice flour showed an almost 2.2-fold increase in protease activity followed by wheat flour, which showed a 1.85-fold increase over the basal media. However, supplementation of potato starch, corn starch, and ragi exerted an inhibitory effect on alkaline protease production. Protease production by Bacillus sp. Y was suppressed up to 80% in the presence of most of the organic and inorganic nitrogen sources tested in comparison to rice flour:peptone supplementation. Hence, based on the optimization studies, we achieved a yield of 88 PU/mL (2.2-fold increase) with the Bacillus sp. Y when cultivated for 72 h at pH 7.5, 37 °C in a medium containing: rice flour (1%, w/v), NaCl (0.5%, w/v), and skim milk (10%, v/v) with Na_2CO_3 (0.4%, w/v).