Optimization of keratinase production by Bacillus SLII-I bacteria in chicken feather waste medium

Keratin is an undissolved protein in water and difficult to transform by proteolytic enzymes because there is a cystine disulphide bond. One of the bacteria that produce keratinase enzyme is Bacillus sp. which is able to break the disulfide bond on the keratin protein into a soluble protein. The purpose of this research is to produce keratinase optimally through analysis of bacterial growth profile, protein content, and keratinase activity by varying pH conditions and composition of chicken feather waste medium. The optimization of keratinase was based on the growth curve of bacteria cultured on 3 medium types namely Nutrien broth, minimal medium feather meal, minimal medium feather meal pepton 1% and 3 types of pH 7, 8, and 9, for keratinase activity from crude enzyme extract, While for protein profile analysis using ammonium sulphate method, isoelectric point, and SDS-PAGE was done to find out protein profile. From the result of optimum keratinase production from minimal medium feather meal pH 7, the highest keratinase enzyme activity was 0.34 unit / ml. The isoelectric point of the keratinase enzyme is known at pH 5.3 while the molecular weight based on the SDS-PAGE yield is 38kDa.