Improvement in lignocellulose degradation and humus synthesis by adding gallic acid during cow manure composting

The positive effects of adding polyphenols on humification have been widely explored during composting. However, the precise impact of polyphenols on the breakdown of lignocellulose throughout the composting process has not yet been elucidated. Two experimental treatments were designed to explore the mechanism by which adding natural organic phenols affected interactive relationship between lignocellulose hydrolysis and humus synthesis: a control group and a gallic acid (GA)-amended group. The results indicated that GA effectively promoted the transformation of polyphenols. Degradation rates of lignin and cellulose increased by 42.3 % and 20.6 %, respectively. Meanwhile, the synthesis of highly humified component 3 of humic acid increased by 22.1 % in GA group. GA dramatically enriched core bacteria associated with humic acid components. Structural equation model showed that GA directly stimulated microbial decomposition of lignocellulose and indirectly accelerated its degradation by enhancing microbial utilization of polyphenols. These enhancements in polyphenol transformation and lignin degradation collectively promoted compost humification. The addition of GA presents a highly promising approach to accelerate the degradation of recalcitrant lignocellulose and promote compost humification, while simultaneously addressing the waste generated during the production process of polyphenols.