Characterization and Production Optimization of Keratinase from Three Bacillus Strains

Indonesia has large coastal areas. The fisheries are good for exploitation. In the previous studies, bacteria producing keratinase were isolated from fish market waste. Keratinase enzyme is able to degrade keratin on the skin. Enzyme activity is influenced by external conditions, such as pH, temperature, and incubation time. The study aimed to investigate the characteristics and the optimal conditions of the keratinase production. The materials used were keratinase from three Bacillus strains: Bacillus thuringensis BRAW_PT, Bacillus aerius BRAW_PB, and Bacillus subtilis BRAW_PI. The keratinase was investigated by sodium dodecyl sulfate (SDS PAGE) and nondenaturing polyacrylamide gel electrophoresis (Native PAGE). Conditions of the production were optimized by pH, temperature and incubation time on enzyme activity. The molecular weights of all keratinases from Bacillus species were 94.803 kDa and 70.115 kDa. The optimum activity of keratinase from B. thuringensis BRAW_PT and B. firmus BRAW_PI was obtained at pH 8, while keratinase from B. aerius BRAW_PB was optimal at pH 6-8. Keratinase from B. thuringensis BRAW_PT has maximum activity at 25°C, whereas keratinase from B. aerius BRAW_PB and B. firmus BRAW_PI at 29°C. All keratinases from Bacillus species are optimal at 90 minutes incubation. Based on the principal component analysis (PCA), B. thuringensis BRAW_PT was discriminated from the other enzymes.