Leaching risk of antibiotic resistance contamination from organic waste compost in rural areas

Composting is an important decentralized technology for treating multiple biodegradable organic wastes in rural areas. However, compared to industrial composting (i.e., time and temperature protocols), rural composting is less well-controlled, and the risk of antibiotic resistance genes (ARGs) in these composts needs to be determined. We performed a quantitative determination of ARGs and both prokaryotes and eukaryotes to investigate the liquid-solid leaching ratio and the relationship between ARGs and microbial communities in solid and water extracts of composts collected from rural areas. We observed a high level of sulfonamides resistance genes and tetracyclines resistance genes (10^-4-10^-2 copies/16S copies). Tet-C and tet-X show the strongest leaching potential in rural organic waste composts with complex hosts in solid and liquid phases. This study showed high ARG abundances in compost solid and water extracts, highlighting the leaching risk of compost ARGs when exposed to runoff or groundwater during open storage and field application.