Optimization of keratinase production from Pseudomonas oleovorans K1 and Acinetobacter variabilis K2, bacterial isolates obtained from poultry feather waste

Feathers, a major poultry industry by-product, present an environmental challenge due to improper disposal and their resistant nature. A primary method employed to degrade these feathers involves the use of keratinase, an enzyme that breaks down keratin, the principal component of poultry feathers. This study aimed to isolate keratinase-producing bacteria from poultry waste soil collected from Vazhayur, India. The process involved enrichment using feather meal broth followed by isolation and screening through skim milk agar, keratinase plate assays and feather degradation tests. Among the 10 isolates, three isolates designated as isolate 1, 2 and 10 exhibited high keratinase activity. These were identified as Pseudomonas oleovorans K1 (Isolate 1), Acinetobacter variabilis K2 (Isolate 2) and Bacillus tropicus K10 (Isolate 10) respectively. The highest keratinase activity, 29.80±0.36 U/ml, was observed in P. oleovorans, while keratinase derived from A. variabilis demonstrated an activity of 26.23±0.39 U/ml. Optimization of keratinase production revealed that optimal conditions for maximum production included the presence of basal media supplemented with 1% keratin, at pH 7, incubated at 35 °C for 48 hours. Following optimization, an almost two-fold increase in keratinase production was observed highlighting the isolates potential to be used for large scale production of keratinase.