Study on the synergistic inhibition of Staphylococcus aureus and bacterial diversity in chicken manure by Bacillus velezensis and Black soldier fly larvae

In order to study the killing efficiency of pathogenic microorganisms and reduce potential transmission risks during the resource utilization of chicken manure by Black soldier fly larvae（BSFL）（Hermetiaillucens）. Staphylococcus aureus was used as an indicator bacterium to monitor its population changes during the transformation process, thereby exploring the trend of pathogenic bacteria in chicken manure. Additionally, microbiome analysis was employed to analyze shifts in microbial communities and to predict changes in the abundance of pathogenic microorganisms. The results showed that the bacteria initially increased slightly and then gradually decreasing in CK group and bacteria rapidly decline in T group. By the 192nd hour, the bacteria count in the T group had dropped to 0.2×10⁸ cfu·g⁻¹, which was significantly lower than that in the CK group（1.0×10⁸ cfu·g⁻¹）. The synergistic bioconversion of chicken manure by Bacillus velezensis and BSFL（T group）significantly reduced the abundance of Staphylococcus aureus in chicken manure compared to the BSFL group（CK group）, decreasing from an initial amount of 0.9 × 10⁵ cfu·g⁻¹ to 8.7 × 10² cfu·g⁻¹（T group）and 7.9 × 10³ cfu·g⁻¹（CK group）, respectively. Bacillus velezensis enhanced the microbial diversity in the chicken manure transformation process, significantly affecting the microbial composition at 72 h of transformation by inhibiting the proliferation of Pseudogracilibacillus and Ignatzschineria species. However, its impact on the microbial community composition in the later stages was not significant. The functional bacteria analysis revealed that the potential pathogenic microbial count in the T72 group was significantly lower than that in the CK72 group, indicating that Bacillus velezensis has a strong inhibitory effect on potential pathogenic microorganisms. This study provides a theoretical basis for biosafty to apply black soldier flies and functional microorganisms to produce high-value alternative proteins from organic waste.