Selection and identification of efficient chicken feather-degrading bacteria

In Thailand, a large amount of chicken feather waste is generated from the process of chicken meat production, causing environmental pollution. Chicken feathers can be used as a raw material to produce protein supplements for animal feed or bioactive keratin peptides for food, cosmeceutical, and medical products. Degradation of chicken feathers by microorganisms and their enzymes is a feasible solution for producing the protein hydrolysate or keratin peptides. This study aimed to screen, select, and identify efficient chicken feather-degrading bacteria. Of the total 108 strains investigated, only 15 strains showed high chicken feather-degradation abilities, and just 3 strains had feather-degrading capabilities greater than 80%, namely CP2.4 (82.33%), LY4.9 (82.45%), and R22 (80.11%). Moreover, high soluble protein amounts of 258.78, 267.67, and 235.11 mg/g chicken feathers were found in the culture supernatants of strains CP2.4, LY4.9, and R22, respectively. The CP2.4, LY4.9 and R22 strains were identified to be closely related to Bacillus subtilis. Furthermore, MTT assay showed the protein hydrolysate obtained from LY4.9 had no toxicity to an animal cell line, namely L-929 at the highest concentration tested, while protein hydrolysates obtained from CP2.4 and R22 were toxic to the cell. Therefore, Bacillus subtilis LY4.9 can be considered safe and suitable for chicken feather degradation to produce protein hydrolysate for use as a protein supplement in animal feed or to produce keratin-peptides. The application of this research would add value to the chicken feather waste and help tackle the associated problem of industrial pollution.