Pig manure often carries antibiotics resistance bacteria (ARB) because antibiotics are usually added in feed. Composting is an effective way to reduce the environmental risk of pig manure returning to the field

but the characteristics of ARB in pig manure composting products are still unclear. The purpose of this study was to reveal the species

number

and distribution of ARB in pig manure composting products. In this study

the number

resistance

and species of resistant bacteria contained in the composting of pig manure and pig manure with additional chlortetracycline (CTC) were investigated through measures such as plate counting

minimum inhibitory concentration (MIC) of antibiotic

and 16S rRNA sequencing. Results show that the number of culturable bacteria in composting process first increased and then decreased

and the number of culturable bacteria in compost was far less than that in fresh manure samples. Antibiotics residues such as CTC

enrofloxacin (ENR)

erythromycin (ERY)

and sulfamerazine (SMZ) were detected in pig manure samples. At the end of composting

ENR resistant bacteria in the compost increased slightly

while SMZ

ERY

and CTC resistant bacteria were effectively reduced. A total of 25 strains of ARB were screened out

and the detection rate for multi-ARB was 20%. Aerobic composting is effective to reduce the number and types of ARB

but there are still a small number of multi-ARB

which poses a potential threat to the environment.