Keratinolytic Potential of Feather-Degrading Bacillus polymyxa and Bacillus cereus

Keratinolytic abilities of Bacillus polymyxa B20 and B. cereus B5esz were evaluated in liquid cultures in mineral media containing chicken feathers. Both tested strains were capable of effective liquefying and biodegradation of feather keratin, up to 56.5 – 72.1% in ten-day cultures, releasing considerable amounts of hydrolysis products. Tested bacteria were mesophilic species, producing highest activity of keratinases and proteases in the presence of keratin (1%) as a sole nutrient source or keratin supplemented with yeast extract, at 30oC. Keratinases of B. polymyxa were predominantly highly alkaline serine proteases, with optimum activity at 50oC, while B. cereus produced mainly a mixture of neutral proteases, optimally active at 45oC. Keratinolytic potential of tested bacterial strains could find a variety of applications, including utilization of keratinous waste from poultry industry and obtaining keratin hydrolysate-based soil fertilizers.