The key metabolic pathway for enhanced anaerobic digestion of chicken manure with coal slime for methane production

Coal slime can significantly enhance anaerobic digestion (AD) of chicken manure (CM) for methane production; However, the underlying mechanism is still unclear. This study has mainly discussed variation characteristics of key metabolic pathways in the AD process of CM by coal slime. Dry CM and coal slime (CS) were selected and coal seam mine water was applied as bacteria source. CS effects on the metabolic pathway of CM fermentation system were studied by biogas production simulation experiments and metagenomic analyses. The results indicated that variations in pH and CS amount exerted significant effects on the biogas generation in the contest of CM fermentation. Optimal conditions for enhanced biogas production were observed when the pH approached neutrality, and the CS quantity was 0.2 g, highlighting substantial potential of CM for biogas generation. The addition of CS resulted in a 13.1%, 1.9%, and 1.8% increase in the relative abundance of Bacteroides, Aminobacterium, and Methanothrix. This, in turn, elevated gene abundance of essential enzymes in the glycolytic pathway (glycolysis and pyruvate metabolism), promoting acetic acid production and providing a foundational basis for methanogen metabolic gas production. Furthermore, the addition of CS lead to a notable increase in the abundance of the pilA gene in Methanocorpusculuma (111.5%) and Methanothrix (66.1%). This suggested the involvement of CS in DIEF, thereby augmenting the anaerobic methane production potential of CM. These outcomes offer valuable theoretical insights for optimizing the biogas production potential of CM and maximizing the resource utilization of CS.