Production of alkaline protease and biosurfactant from waste breads using bacillus subtilis

In this study, the alkaline protease and biosurfactant from Bacillus subtilis isolated from soil sample were produced and characterized. The culture conditions were optimized for maximum alkaline protease production. The best carbon and nitrogen sources for maximum alkaline protease production were 1% waste bread powder and 1% casein, respectively. In addition optimal pH 10.5, temperature 37ºC, agitation rate 200 rpm, inoculum size 5%, inoculum age 4 hours, waste bread powder 1% were determined. Also maximum enzyme production was detected when using baffled erlenmeyer flask. The production of a biosurfactant by Bacillus subtilis was also studied. In hemolytic activity, Bacilllus subtilis showed very good hemolysis and diameter of the hemolytic zone was larger than 3 cm was evaluated as complete hemolysis (++++). Xylen was the best substrates for emulsification (68%). Surface tension of biosurfactant was determined 48.64 mN/M using pendant drop method. The rhamnose test was positive which indicates that biosurfactant could be of rhamnolipid type. It had a good foaming, antimicrobial and antifungal activities. Furthermore, it showed stability during exposure to high temperatures, high salinity and a wide range of pH. Consequently, due to the characteristic features of alkaline protease and biosurfactant produced by Bacillus subtilis their together use will provide improved wash efficiency as a detergent additive.