The production of protease by Penicillium sp. LCJ228 was optimized under submerged fermentation. Nutritional and physical factors that influence protease production were optimized by one factor at a time (OFAT) method in order to achieve high yield of protease. Maximum protease production was obtained on the 4th day in a liquid medium containing glucose (15 g/L), yeast extract (15 g/L), black gram husk (10 g/L) with an initial pH of 10 and an inoculum size of 2 g/L of fungal mycelium. About 2.4 fold increase in protease production was observed in the optimized medium. The maximally yielded crude protease was then precipitated and characterized by SDS-PAGE and native-PAGE. The molecular weight of the ammonium sulphate precipitated protease was ~66 to 70 kDa and native-PAGE showed three isoenzymes. The crude and precipitated protease had the ability to completely remove blood stains on cotton fabric indicating its potential to be used as a stain remover in detergents.
Key words: Protease, Penicillium sp., submerged fermentation, conventional optimization, blood stain removal
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