Characterization of alkaline keratinase of Bacillus licheniformis strain HK-1 from poultry waste

Abstract- A feather-degrading Bacillus licheniformis strain HK-1 was isolated from poul-try waste. High keratinolytic activity was observed when it was cultured on broth contain-ing native feather powder. The B. licheniformis strain HK-1 was identified on morphologi-cal and biochemical tests and 16S rRNA sequencing. Maximum keratinase production was observed at 50 ºC and initial pH of 8.0. The enzyme was active over a wide range of pH (with optimum 11.0) and temperature (with optimum 60 ºC) and was relatively heat stable (up to 60 ºC). The enzyme molecular weight was estimated about 46 kDa by SDS-PAGE. Complete feather degradation was achieved at 60 ºC in 3 days incubation in cul-ture supernatant. Keratinolytic activity was partially inhibited by EDTA, 1,10-phenanthro-line, NaCl and PMSF. It was however notably inhibited by ZnCl2. Keratinolytic activity was on the other hand increased by DMSO, TritonX-100, SDS, CaCl2 and sodium sulphite. The bacterium seems to present potential use for biotechnological processes involving keratin hydrolyses. Key words: Bacillus licheniformis HK-1, alkaline keratinase, chicken feather