Chryseobacterium aquifrigidense keratinase liberated essential and nonessential amino acids from chicken feather degradation

Keratinous biomass valorization for value-added products presents a high prospect in ecological management and the advancement of the bio-economy. Consequently, soil samples from the poultry dumpsite were collected. The bacteria isolated on the basal salt medium were screened for keratinolytic activity. The potent chicken feathers degrading bacteria were identified through 16S rRNA gene sequencing and phylogenetic analysis. Fermentation process conditions were optimized, and the amino acid compositions of the feather hydrolysate were likewise quantified. Ten (10) proteolytic bacteria evaluated on skimmed milk agar showed intact chicken feather degradation ranging from 33% (WDS-03) to 88% (FPS-09). The extracellular keratinase activity ranged from 224.52 ± 42.46 U/mL (WDS-03) to 834.55 ± 66.86 U/mL (FPS-07). Based on 16S rRNA gene sequencing and phylogenetic analysis, the most potent keratinolytic isolates coded as FPS-07, FPS-09, FPS-01, and WDS-06 were identified as Chryseobacterium aquifrigidense FANN1, Chryseobacterium aquifrigidense FANN2, Stenotrophomonas maltophilia ANNb, and Bacillus sp. ANNa, respectively. C aquifrigidense FANN2 maximally produced keratinase (1460.90 ± 26.99 U/mL) at 72 h of incubation under optimal process conditions of pH (6), inoculum side (5%; v/v), temperature (30°C), and chicken feather (25 g/L). The feather hydrolysate showed a protein value of 67.54%, with a relative abundance of arginine (2.84%), serine (3.14%), aspartic acid (3.33%), glutamic acid (3.73%), and glycine (2.81%). C. aquifrigidense FANN2 yielded high keratinase titre and dismembered chicken feathers into amino acids-rich hydrolysate, highlighting its significance in the beneficiation of recalcitrant keratinous wastes into dietary proteins as potential livestock feed supplements.