Molecular Identification and Characterization of Keratinase-Producing Bacteria from Poultry Waste Sites in Enugu State

Abstract

Introduction: Feather waste poses an environmental challenge because keratin is a structural fibrous polypeptide protein that is highly resistant to proteolytic degradation due to its complex bonding structure, which is stabilized by disulfide and hydrogen bonds. Aim: In this research, we aimed to identify and characterize the bacteria keratinase that possess the ability to degrade keratin isolated from some poultry waste dumping sites in Enugu state, Nigeria. Materials and Methods: Six waste soil samples were collected from three different locations, two from each location. A total of thirty bacterial isolates were obtained from the three poultry waste sites. Protease activity served as the main criterion for screening these isolates on skim milk agar plates. Results: Five of the thirty isolates exhibited proteolytic activity and were further confirmed to possess keratinolytic activity on feather basal medium. Within fifteen days, the test showed nearly complete feather degradation. However, three bacterial isolates—FDS1, GARMS1, and GMIS1—that exhibited the highest keratinase activity were characterized. Further identification using 16S rRNA gene sequencing confirmed their molecular identities. Results on molecular characterization revealed that the isolates FDS1, GARMS1, and GMIS1 belong to the genus Bacillus. The isolates showed more than 95% similarity with Bacillus subtilis subsp. stercoris strain 153. Conclusion: The soils from the Gariki Awkunanaw waste dumping sites, regardless of location, contained Bacillus subtilis subsp. stercoris strain 153.