Chlorophenol pretreatment enhanced dual-function of laccase to promote lignin humification during composting

During straw composting, chlorophenol was used as microbial pre-culture medium to induce laccase expression for improving synergistic metabolism of lignin and phenolic compounds. A significant increase of 71.5 % in humic acid concentration and 104.6 % humification index were observed in chlorophenol-treated group (CP) compared to control group (CK). The germination index of CP plants was also 40.5 % higher than that of CK, indicating that the chlorophenol did not cause the toxicity of the compost, but also promoted the effectiveness of the products. Co-occurrence network analysis and unsupervised machine learning models revealed that chlorophenol enhanced microbial cooperation and expanded microbial functional networks. This not only improved the expression of laccase genes but also activated the humification pathways (i.e., lignin-protein and polyphenol-protein theories), ultimately enhancing humic substance formation. This study fills a gap in understanding the mechanisms underlying the synergistic treatment of feasible pollutants. These findings have significant implications for organic solid waste management and pollution control.