Analysis for microbial denitrification and antibiotic resistance during anaerobic digestion of cattle manure...

This study investigated the effects of tylosin (0, 10, and 100 mg/kg dry weight) on the denitrification genes and microbial community during the anaerobic digestion of cattle manure. N₂ emissions were reduced and N₂O emissions were increased by 10 mg/kg tylosin. Adding 100 mg/kg tylosin increased the emission of both N₂O and N₂. The different responses of denitrifying bacteria and genes to tylosin may have been due to the presence of antibiotic resistance genes (ARGs). Network analysis indicated that denitrification genes and ARGs had the same potential host bacteria. intI1 was more important for the horizontal transfer of denitrification genes and ARGs during anaerobic digestion than intI2. The anaerobic digestion of manure containing tylosin may increase nitrogen losses and the associated ecological risk.