Characterization of Protein-Rich Hydrolysates Produced Through Microbial Conversion of Waste Feathers

The poultry industry generates huge amounts of feather waste, which needs appropriate management to avoid environmental harm. Keratinolytic potential of Chryseobacterium sp. kr6 and Bacillus sp. kr16 was exploited for feathers bioconversion to produce protein hydrolysates. Increasing feather concentrations (10, 20, or 50 g/L) had minor effects on feather degradation by strain kr6, although the performance of strain kr16 was diminished as the feather concentration increased in culture media. At 50 g/L, strain kr6 degraded 75 % of the feathers after 96 h, and strain kr16 degraded 21 %. The feather-degrading efficiency of Chryseobacterium sp. kr6 was corroborated by a direct relationship between feather concentration and the content of released soluble protein and free amino acids, in comparison to Bacillus sp. kr16. In vitro analyses were performed to postulate feather hydrolysates as animal feed supplements. Digestibility of the hydrolysates was lower when compared to controls (soy protein and casein), but higher than feather meal (FM), which is a usual ingredient of animal feed. Methionine was the first limiting essential amino acid in the hydrolysates and FM; however, the protein digestibility-corrected amino acid scoring was higher for the hydrolysates. Predicted protein efficiency ratio and biological value of kr6 hydrolysates were higher than kr16 hydrolysates and FM. Hydrolysates produced through feathers bioprocessing could be considered as interesting protein-rich resources for animal feed, thus representing an alternative for the valorization of waste feathers.