Bioconversion of Poultry Feather Waste by Bacillus subtilis Strain FWD5: A Sustainable Approach

Feather waste generated by poultry industries primarily composed of recalcitrant keratin protein, poses a significant environmental concern due to its accumulation in landfills and resistance to degradation. In this study efficient keratinolytic bacterium FWD5 capable of degrading poultry feathers and to optimize the biodegradation parameters one variable at a time (OVAT) approach was used. Isolate FWD5 demonstrated the enhanced keratinase production on FMA plate and was identified as Bacillus subtilis through 16S rRNA gene sequencing. The effect of various physicochemical parameters including incubation time, substrate concentration, temperature, pH, and inoculum size on feather degradation was investigated. Optimal keratinase activity (21.08 U/mL) and soluble protein release (891.20 µg/mL) were observed on the fourth day of incubation. The highest degradation efficiency was achieved at 1% feather concentration (16.11 U/mL and 896.25 µg/mL), 35°C temperature (20.13 U/mL & 930.33 µg/mL), pH 7 (16.11 U/mL and 982.00 µg/mL) and 2% inoculum load (17.66 U/mL and 983.43 µg/mL). Scanning electron microscopy (SEM) confirmed the structural breakdown of feathers post-incubation. The findings highlight the potential of B. subtilis as an eco-friendly agent for effective bioconversion of keratinous waste into valuable by-products.