Influence of community complexity and regulation by two-component system on community stability in aerobic composting in the presence of penicillin residues

Aerobic composting technology offers an effective solution for addressing antibiotic residues. Despite advancements in improving composting materials and understanding microbial community composition, exploring the impacts of residual antibiotics on microbial community complexity, stability, and functionality is essential. In this study, the mechanisms related to the impacts of residual antibiotics were analyzed using chicken manure and straw as raw materials, with residual penicillin at different concentrations as the environmental stressor. Highthroughput sequencing technology was employed to reveal the characteristics of the bacterial community. The results showed that compared with the CK group (i.e., without penicillin residue), the FHA group (i.e., with 400 mg/kg penicillin residue) exhibited an increase in network topological features such as nodes (384), edges (17320), average degree (90). Additionally, there was a decrease in modularity (1.69) and the average path length (0.24) and an increase in the species and number of bacteria. These findings collectively indicated a tighter network state, a rich and varied bacterial composition, and closer interspecies interactions in the FHA group, indicating that the initial high concentration of penicillin residue could enhance microbial community complexity. The FHA group exhibited a gradual increase in both robustness and vulnerability compared with the CK group. Additionally, bacterial community cohesion improved from 0.84 to 0.93 by day 35, indicating that the FHA group exhibited the highest level of community stability. The KEGG pathway analysis highlighted the prominent role of two-component systems (TCSs) in community stability, whereas no pathways were found to impact community complexity. In the THA (200 mg/kg penicillin residue) and FHA groups, 36 and 34 differentially expressed TCS genes were identified, respectively. These genes were involved in various functions such as quorum sensing, biofilm formation, and bacterial chemotaxis. In conclusion, the initial high concentration of penicillin residue could enhance both the complexity and stability of the community. Residual penicillin presumably regulated community stability by influencing the differential expression of TCS genes. These findings contribute to a deeper understanding of community stability in aerobic composting, offering insights for optimizing aerobic composting methods.