Production of keratinase by Bacillus subtilis S14

Abstract

Bacillus subtilis S14 produces KerS14, a keratinase with potential application in the leather industry, since this enzyme does not damage bovine collagen. This work presents the optimization of a medium composed of feather meal and CaCl2 for the production of keratinases by B. subtilis S14. The keratinase activity of the keratinolytic crude extract obtained from B. subtilis S14 cultivated in the optimized medium (this preparation was named KceBs14) was characterized. KceBs14 activity remains thermostable at 50 °C for 216 h and has an optimum temperature of 50 °C. Moreover, KceBs14 hydrolyzes horns, retaining its enzymatic activity after the process. Additionally, a scale-up to a 5 L bioreactor was performed. Maximum keratinase production was obtained with aeration rate of 1 vvm, agitation of 400 rpm and an oxygen mass transfer rate of 24.48 h−1. These results reveal that it is possible to define a simple medium to produce keratinases on a bioreactor scale within short fermentation times. These enzymes have a potential application in biotechnological processes, like horn degradation, which require thermostability at 50 °C for long periods.