Abstract

Bacillus Subtilis is a saprophytic bacteria which has a widespread distribution in nature and can be easily isolated from soil microbes. Bacillus Subtilis AS1.398 is a major strain of Bacillus Subtilis used extensively in light industry and the pharmaceutical industry and is commonly used in the leather industry in China for depilation and bating. The non-collagenolytic activity of caseinase is correlated with the depilation. Collagenolytic protease has little contribution to depilation. It damages the collagen fibres and reduces the quality of leather. Collagenolytic activity should be inhibited during enzymatic depilation.

Caseinase and collagenase were isolated and purified to homogeneity from commercial Bacillus Subtilis AS1.398 by affinity chromatography on the basis of modified hide powder as supporter. The purified enzyme had an estimated molecular mass of 44.3kDa determined by SDS-PAGE. Assays were also made on the activities of the two proteases. The specific activity of the caseinase showed a recovery of 42%.