Keratinolytic activity of Kocuria rosea

A strain of Kocuria rosea able to secrete keratin-hydrolysing proteinases (keratinases) in submerged batch cultures with finely milled feathers as carbon and nitrogen sources was studied. The highest production of keratinases was obtained when feathers were used as the only fermentation substrate ( 17 U/mg). Considerably lower activity was present in cultures containing glucose and others nutrient supplements. The optimum temperature and pH for keratinolytic activity was 40 degreesC and 10, respectively. Gelatin-sodiumdodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) electrophoresis analysis showed that Kocuria rosea grown on feathers secreted at least two alkaline extracellular proteases with apparent molecular weights of 90.2 and > 200 kDa, respectively. These proteolytic activities appear sequentially during microbial growth. Keratinolytic activity was strongly inhibited by phenylmethanesulphonyl fluoride (PMSF), chymostatin and crystalline soybean trypsin inhibitor, indicating the presence of serine proteases. Proteolytic enzymes derived from the biodegradation of feathers by this microorganism could be a useful biotechnological tool in the leather, food and cosmetic industries.