A new study published in International Microbiology has demonstrated how two keratin-degrading bacteria — Pseudomonas aeruginosa PA1045 and Alcaligenes faecalis IHB B 6507 — can transform chicken feather waste into nutrient-rich organic fertilizer. With billions of tons of poultry feathers produced globally each year, their disposal remains a major environmental challenge due to keratin’s insoluble, highly resistant structure.
The researchers optimized keratinase production by adjusting temperature, pH, substrate concentration and inoculum size. Peak keratinase activities reached 42.48 U/mL for P. aeruginosa at day 5 and 40.88 U/mL for A. faecalis at day 7. Feather degradation efficiency was visually confirmed, with 22% weight loss for P. aeruginosa and 18% for A. faecalis after 10 days.
To understand how the feathers were transformed, the team characterized the chicken-feather hydrolysates (CFH) using Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR). SEM images revealed disrupted, fragmented feather microstructures, confirming the breakdown of keratin fibers. FTIR spectra showed distinct amide and functional-group peaks, indicating structural changes and the presence of protein-derived compounds.
Further biochemical analysis found that the hydrolysates contained soluble proteins and essential amino acids, with L-threonine emerging as the most abundant in both bacterial treatments. Nitrogen content was also high: 6.688% in the P. aeruginosa hydrolysate and 5.722% in the A. faecalis hydrolysate.
When applied to maize plants as organic fertilizer, both hydrolysates produced impressive growth enhancement. Plants treated with the P. aeruginosa hydrolysate showed the highest shoot height, while those treated with A. faecalis displayed the greatest root length and leaf area. In several parameters, the hydrolysates outperformed conventional NPK fertilizer, demonstrating their agronomic value.
Overall, the study highlights a sustainable, biotechnology-driven approach to valorizing poultry feather waste. By converting a difficult-to-decompose byproduct into a functional biofertilizer, these keratinolytic bacteria offer an environmentally friendly solution with potential applications in organic agriculture and circular-economy systems.
Reference
Otuyelu, F.O., Omojasola, P.F., Adebisi, O.O. et al. Bioconversion of chicken feather waste: optimizing keratinase production by Pseudomonas aeruginosa PA1045 and Alcaligenes faecalis IHB B 6507, characterization and application as organic fertilizers. Int Microbiol (2025). https://doi.org/10.1007/s10123-025-00750-8
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