Chryseobacterium cucumeris FHN1 keratinolytic enzyme valorized chicken feathers to amino acids with polar, anionic and non-polar imino side chain characteristics

Abstract

Keratinolytic bacteria were isolated from poultry sludge samples using chicken feathers formulated media, and the identities of potent isolates were confirmed through 16S rRNA gene sequencing. Fermentation process conditions were optimized, and the amino acid profile of the feather hydrolysate was determined. Ten proteolytic bacteria were obtained from 20 isolates recovered from the samples with halo zone diameters on skimmed milk agar ranging from 15.5 ± 0.71 mm for PSW-15 to 28 ± 1.41 mm for PSW-08. The proteolytic bacteria showed percentage chicken feathers degradation that ranged from 29% for PSW-11 to 84% for PSW-14, and keratinase activity ranged from 99.99 ± 5.14 U/mL for PSW-15 to 761.82 ± 27.42 U/mL for PSW-14. The most potent isolates coded as PSW-14 and PSW-16 were identified as Chryseobacterium cucumeris FHN1 and Sphingobacterium multivorum HNFx, nucleotide sequences were submitted to the GenBank with accession numbers MW165487 and MW165488, respectively. C. cucumeris FHN1 showed the maximum keratinase activity of 1030.90 ± 15.42 U/mL after 72 h, at optimized fermentation conditions of initial medium pH 5–6, inoculum size (4%, v/v), chicken feather (1%, w/v), and incubation temperature (25 °C). The amino acid analysis showed serine (5.19%), aspartic acid (4.75%), glutamic acid (5.86%), and proline (6.08%) were relatively high in concentration and these amino acids possess polar, anionic and non-polar imino side chain characteristics. The chicken feathers-degrading capacity and the amino acid composition of the feather hydrolysate underpin C. cucumeris FHN1 dexterity with keratinous biomass valorization into valuable products with biotechnological application potentials.