Effect of Thermophilic Microbial Agents on Antibiotic Resistance Genes and Microbial Communities during Co-Composting of Pig Manure and Tea Stalks

Antibiotic resistance caused by antibiotic resistance genes (ARGs) threatens human health. ARGs in animal manure can be degraded by composting. This study explored the changes in ARGs and microbial communities during co-composting of pig manure and tea stalks with (T) thermophilic microbial agents, including Geobacillus toebii ZF1 and Geobacillus sp. ZF2 for 15 days in a 4 L vacuum flask. Composting without thermophilic microbial agents served as control (CK). The results showed that the compost temperature of group T peaked at 72.1 °C and maintained above 70 °C for 4 days. The maximum temperature of group CK was 64.0 °C. The seed germination index showed that group T had reached maturity on day 9, while group CK reached maturity on day 15. The dominant bacteria in group CK were Bacillus. In group T, the dominant bacteria changed from Bacillus and Corynebacterium to Geobacillus. Compared with that of group CK, group T increased the removal of cmx, baeS and TaeA by 24.6%, 18.6% and 12.1%, respectively. Group T promoted and inhibited the removal of arlR and novA, respectively (p < 0.05), while group CK showed the opposite effect. Network analysis suggested that group T effectively inactivated Dietzia, Clostridium and Corynebacterium (p < 0.05) and promoted the removal of cmx and baeS. These results showed that thermophilic microbial agents could accelerate the maturation of pig manure and tea stalks, change microbial communities and promote the removal of ARGs. It is of great significance to reduce the spread of ARGs and, in turn, human health risks.