Sphingobacterium multivorum HNFx produced thermotolerant and chemostable keratinase on chicken feathers

Microbial keratinase dexterity for keratin bioconversion into protein hydrolysates with high economic value is premised on its unique hydrolytic properties. Consequently, a novel keratinolytic Sphingobacterium multivorum HNFx (NCBI: MW165488.1 ) was grown on chicken feathers as the only source of carbon and nitrogen. Accordingly, extracellular keratinase production by the isolate was enhanced by optimizing various physico-nutritional parameters. The amino acid composition of the feather hydrolysate was analyzed, and the biochemical properties of the produced keratinase were evaluated. The results of the study indicated that HNFx elaborated maximum keratinase (1526.36 ± 8.99 U/mL) 72 h post-incubation. Analysis of the feather hydrolysate showed various amino acids with a relatively high abundance of aspartic acid (3.63%) and glutamic acid (3.56%), with significant concentration of arginine (2.44%), serine (2.08%), glycine (2.06%), and leucine (2.03%). HNFx keratinases showed optimal activity at pH of 8 and temperature of 90 o C. Metal ion chelators; EDTA and 1,10-phenanthroline inhibited the enzyme activity, suggesting a metallokeratinase. The enzyme activity was remarkably enhanced by chemical agents; SDS, triton X-100, DMSO, H 2 O 2, and metal ions; Al 3+ , Ba 2+ , Ca 2+ , Fe 2+ ; but significantly affected by Zn 2+ and Co 2+ . S. multivorum HNFx has shown the propensity to add value to keratinous wastes through bioconversion into quality protein hydrolysate with immense prospects in the livestock sector. The properties of HNFx keratinase highlight its biotechnological and industrial significance for the development of eco-friendly bioprocesses.