Protection of humus acids in chicken manure compost by inhibiting aromatic degrading bacteria

Microorganisms are a "double-edged sword" for humus (HS) formation in compost. Their degradation activity provides precursors for HS formation, but also leads to HS degradation in nutrient-limited environments. This study aimed to investigate the protective effect of chitosan (CTS) on HS stabilization in compost by inhibiting microbial degradation, taking advantage of CTS's high adsorption efficiency and antibacterial properties. Compared to the control group (CK), the HS contents in the CTSQ group (0 d) and CTSH group (8 d) increased by 9.26 mg/g and 12.91 mg/g, respectively, with the CTSH group showing a significantly better effect on HS content (P < 0.05). Furthermore, CTS significantly reduced the abundance of 18 microbial species capable of degrading aromatic compounds, including Ulvibacter and Brevibacterium, suggesting a possible mechanism by which CTS protects HS from microbial decomposition. These findings provide valuable insights for the practical application of HS stabilization technologies in composting, highlighting the potential of CTS as an effective agent for improving HS preservation.