Sustainable Valorization of Poultry Slaughterhouse Waste Using Bacillus Strains Isolated from Poultry Manure

Traditional methods for managing poultry slaughterhouse waste, such as landfilling or incineration, are often costly and unsustainable. Therefore, identifying microbial strains capable of producing specific compounds that facilitate waste degradation has become essential. Bacillus strains were isolated from poultry manure and selected based on their enzymatic production capacity. Following molecular identification, Bacillus sp. B5J22-F and Bacillus paramycoides B4J22-F were selected for keratinolytic activity quantification and the evaluation of antibacterial activity under varying fermentation parameters. The studied strains exhibited optimal keratinolytic activity at pH 8 (33.0 U/mL for B. paramycoides B4J22-F and 24.9 U/mL for Bacillus sp. B5J22-F) and at a temperature of 45°C (43.6 U/mL for B. paramycoides B4J22-F). Bacillus sp. B5J22-F also achieved its peak activity at the same temperature (28.8 U/mL), demonstrating their effectiveness at elevated temperatures a critical factor in composting processes. Regarding antimicrobial assays, B. paramycoides B4J22-F exhibited the highest inhibition zone against E. coli at 30°C (10.2 mm) and pH 8 (9.1 mm). It also showed notable activity against S. aureus at 30°C (10.6 mm) and against B. cereus at pH 5 (12.9 mm), whereas Bacillus sp. B5J22-F displayed significant activity against S. aureus at pH 10 (14.5 mm). The Bacillus strains selected in this study demonstrated strong potential not only in keratin degradation but also in inhibiting the growth of certain pathogenic microorganisms. These findings support their potential use in the valorization of poultry slaughterhouse waste.