Microbial Degradation of Wool Waste to Increase Soil Fertility as an Effective and Sustainable Approach

The disposal of wool waste poses significant environmental challenges due to its slow biodegradability and accumulation in landfills. This review examines microbial degradation as an eco-friendly strategy for converting wool waste into soil amendments, addressing the limitations of conventional chemical and high-temperature processing methods. Compared to chemical and thermal hydrolysis, microbial approaches operate under milder conditions, require lower energy input, and preserve amino acid integrity, making them more suitable for sustainable agricultural applications. This review critically evaluates recent advances in microbial and biotechnological wool degradation, highlights key limitations associated with the recalcitrant nature of α-keratin, and outlines future directions for developing scalable wool-based biofertilizers. Keratin-degrading microorganisms such as Bacillus, Stenotrophomonas, Pseudomonas, and Rhodococcus facilitate the release of essential nutrients, including nitrogen, sulfur, and carbon, into the soil. The application of degraded wool enhances soil fertility, microbial activity, moisture retention, and crop productivity. However, field-scale standardization, economic feasibility, and process scalability remain key challenges for widespread agricultural adoption. Overall, microbial wool biodegradation offers a sustainable waste-management solution that supports circular bioeconomy principles by transforming waste into a valuable agricultural resource.