Influence of Effective Microbial Additives Inoculation on Indigenous Bacterial Community Dynamics and Co-Occurrence Patterns During the Composting of Mixed Food Waste and Livestock Manure

Sustainable management of organic waste, such as food waste (FW) and livestock manure (LS), is essential for reducing pollution and promoting resource recycling. This study investigated the effects of Bacillus sp. inoculation and biochar addition on composting efficiency, microbial dynamics, and physicochemical properties. Bacillus sp. accelerated the breakdown of cellulose and lignin, reduced moisture content, stabilized pH, and mitigated ammonia volatilization. Biochar reduced ammonia emissions by 17.04%, increasing to 28.89% with Bacillus sp. Next-generation sequencing revealed Bacillus sp. enhanced microbial diversity, suppressed pathogens, and promoted beneficial microbial interactions. LS treatments retained Firmicutes dominance (up to 95.17%), improving nitrogen retention, while FW treatments transitioned to Proteobacteria and Bacteroidota, driving plant material decomposition. By day 35, Bacillus sp. increased late-stage microbial taxa (Deinococcota, Myxococcota), linked to cellulose degradation and pathogen suppression. In FW biochar compost (FWBC), Planococcaceae and Bacillaceae synergistically decomposed complex organic matter. LS biochar compost (LSBC) reduced anaerobic families like Clostridiaceae and Peptostreptococcaceae, lowering methane and hydrogen sulfide emissions. Microbial network analysis highlighted improved cooperation under Bacillus sp., with LSBC sustaining positive interactions at higher dosages. These results demonstrate that microbial inoculants and biochar enhance composting efficiency, nutrient cycling, and environmental sustainability.