Enhanced removal of antibiotic resistance genes during chicken manure composting after combined inoculation of Bacillus subtilis with biochar

•The addition of mixed B. subtilis and biochar increased the temperature and extended the thermophilic period.•A 97% removal efficiency of ARGs and 96% reduction in the abundance of MGEs were achieved.•Tn916/1545 and intI2 were the drivers of ARG variation during composting.•Firmicutes and Actinobacteriota might play an important role in the spread of ARGs.•FM influenced the abundance of ARGs by affecting bacterial composition. This study explored the combined effects of Bacillus subtilis inoculation with biochar on the evolution of bacterial communities, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs) during the composting of chicken manure. The results showed that B. subtilis inoculation combined with biochar increased bacterial abundance and diversity as well as prolonged the compost thermophilic period. Promoted organic matter biodegradation and facilitated the organic waste compost humification process, reduced the proliferation of ARGs by altering the bacterial composition. Firmicutes and Actinobacteriota were the main resistant bacteria related to ARGs and MGEs. The decrease in ARGs and MGEs was associated with the reduction in the abundance of related host bacteria. Compost inoculation with B. subtilis and the addition of biochar could promote nutrient transformation, reduce the increase in ARGs and MGEs, and increase the abundance of beneficial soil taxa. [Display omitted]