Isolation and identification of keratinolytic bacteria from Jember, Indonesia as a biodegradation agent of chicken feather wastes

Chicken feather waste contains compounds consisting of the protein called keratin and other protein. Keratin is derived from chicken feathers and the proteins from chicken organs and blood. The degradation of chicken feather wastes require microorganisms which actively degrade especially keratin compounds, as well as other proteins and blood. This study aimed to screen and identify keratinolytic bacteria hydrolizing other proteins and blood from chicken feather wastes. The degradation of chicken feather keratin and hydrolysis of other protein were assayed by measuring the hydrolysis index of chicken feather keratin and skim milk protein, respectively. Hydrolysis of blood was tested qualitatively using blood agar. Identifying selected isolates used phenotypic and phylogenetic analysis. The strains of GB22.2 and GB23.4 revealed the highest keratinolytic and proteolytic activities, and they could hydrolyze blood. The GB22.2 isolate was most closely related to Bacillus velezensis BCRC 17467T (100% similarity). It is proposed as Bacillus velezensis GB22.2-a novel keratinolytic bacterial species. Bacillus velezensis GB22.2 is species Bacillus velezensis which is firstly reported to be able to degrade chicken feather keratin. The strain of GB23.4 was closely related to Bacillus cereus ATCC 14579T (100% similarity) and it is considered as a new keratinolytic strain of Bacillus cereus. The isolated bacterial strains are new candidates for chicken feather degradation agent.