Mechanism of high-temperature and chemical synergistic pretreatment driving composting humification: Elucidating the roles of compost component transformation and microbial community regulation

The rapid expansion of China’s agro-livestock sector has intensified the challenges of lignocellulosic waste management owing to the recalcitrant structures of these materials during conventional composting. This study evaluated synergistic pretreatment strategies combining high-temperature (110°C) with acid/alkali treatment (0.1 mol/L H 2 SO 4 or Ca(OH) 2 ) to enhance the composting efficiency of cherry wood. Results showed that pretreatment disrupted the lignocellulose structure and functional groups of cherry wood. In addition, combined treatments markedly reduced lignin content (AcHTW: 140.24 mg/g; AlHTW: 161.03 mg/g) than that of single pretreatments (AcYTW: 225.87 mg/g; AlYTW: 221.20 mg/g). Acid-high-temperature (AcHTW) and alkali-high-temperature (AlHTW) pretreatments promoted lignocellulose depolymerization, reducing hemicellulose to 70.62 mg/g (AcHTW) and cellulose to 118.25 mg/g (AlHTW) and 138.90 mg/g (AcHTW), respectively. The high-temperature-based synergistic pretreatments demonstrated superior humification performance, elevating humic acid (HA) content to 225.61–253.84 mg/g with corresponding humification indices (HIX) of 0.732–0.780, representing 6.2–13.2% enhancement over untreated controls (HIX: 0.689). Microbial analysis identified Acinetobacter , Comamonas , Psychrobacter , and Pusillimonas as the dominant genera associated with humification, while Gimesia and Ferrovibrio were positively correlated with lignin degradation. Random forest and PLS-PM modeling indicated that bacterial diversity directly promoted lignocellulose decomposition (path coefficient: 0.274*) and humus formation (0.236*), whereas lignocellulose exerted a strong inhibitory effect on humus accumulation (0.770***). These processes were primarily driven by carbohydrate metabolism (15.68%) and the synergistic action of laccase and cellulase. Overall, acid/alkali-high-temperature pretreatment alleviated microbial inhibition and enriched functional taxa, providing mechanistic insight into lignocellulose valorization during composting. • Combining of high-temperature and acid/alkali pretreatments enhanced composting efficiency. • Lignocellulose exhibited excellent degradation in acid/alkali-high-temperature pretreatments. • Gimesia was significantly positively correlated with FA (r=0.2559 *) and Lignin (r=0.2712*). • Amino acid metabolism (14.55%) and carbohydrate metabolism (15.68%) are the main functional genes. • PLS-PM showed bacterial diversity enhanced lignocellulose degradation (0.274) and humification (0.236).