Abstract:[Background] Keratin is an insoluble protein ubiquitous in animal feathers, hair, and hoofs (feet). In the fields of animal husbandry, livestock and poultry slaughtering, meat processing, leather processing, and wool processing, a large amount of keratin waste is produced, which poses a threat to the environment while being an important source of protein feed.[Objective] To isolate microbial strains producing keratinase from chicken feathers and study their keratin-degrading ability. [Methods] We employed the hydrolysis circle method in skimmed milk powder medium for preliminary screening and determined the keratinase activity of chicken feather in the liquid medium for rescreening. Additionally, we used the amylase screening medium and liquid fermentation medium to investigate the amylase-producing activity of the strain. [Results] Strain CX-2 with a high yield of keratinase was screened from 36 bacterial strains isolated from chicken feathers by flask fermentation. The strain was identified as Bacillus mycoides by colony observation, Gram staining, and 16S rRNA gene sequencing. The fermentation conditions were optimized by single factor experiments. The optimal fermentation conditions of the strain for enzyme production were as follows: fermentation in a 250 mL conical flask containing 100 mL chicken feather liquid medium and 3% inoculum at 30 ℃, pH 8.0, and 120 r/min for 36 h. Under these conditions, the keratinase activity of the strain was up to 274.327 U/mL. In addition, the strain produced amylase with the activity of 0.807 U/mL. [Conclusion] An active keratinase- and amylase-producing bacterial strain CX-2 was discovered from chicken feather waste. The results of this paper provide a theoretical basis for further studying the keratinase and amylase of this strain and their application in keratin waste degradation.
