Biochemical characterization of an alkaline surfactant-stable keratinase from a new keratinase producer, Bacillus zhangzhouensis

A new keratinase producer, Bacillus sp. BK111, isolated from a poultry feather was identified as Bacillus zhangzhouensis , which is the first report for its keratinolytic activity. The keratinase production was optimized, followed by the enzyme purification and characterization using biochemical assays. A 2.34-fold increase was observed in the enzyme production under optimized conditions. The enzyme was characterized as a serine protease with 42 kDa molecular weight, stable in a wide range of temperature and pH with maximum keratinolytic activity at 60 °C and pH 9.5. The enzyme had a wide range of different substrates with the best performance on the feather meal substrate. Metal ions of Ca 2+ , K + , Na + and Mn 2+ enhanced the enzyme activity. The enzyme showed a great deal of stability in the presence of ethanol, methanol, acetone, 2-propanol, dimethyl sulfoxide, Tween-80 and Triton X-100. Dithiothreitol (DTT), as a reducing agent, caused a twofold increase in keratinolytic activity. The half-life of the enzyme at optimum temperature was calculated to be 125 min and the ratio of keratinolytic:caseinolytic for the enzyme was 0.8. Our results showed the remarkable features of the enzyme that make it suitable for biotechnological usages.