Effects of adding different surfactants on antibiotic resistance genes and intI1 during chicken manure composting

Aerobic composting is usually employed to treat livestock manure. In this study, a bio-surfactant (rhamnolipid, RL) and chemical surfactant (Tween 80, Tw) were added to chicken manure during composting and their effects were determined on the variations in ARGs and intI1. After composting, the reductions in the RAs of ARGs and intI1 with the addition of Tw (1-4.7 logs) were generally greater than that with the addition of RL (0.8-3.7 logs) and the control (CK) (0.3-2.6 logs), and the enrichment of ARGs was higher with CK (0.9-1.8 logs). The ARG profiles were affected significantly by temperature and the water-soluble carbon contents. RL and Tw effectively reduced the concentrations of bio-available Cu and Zn, thereby hindering the co-selection of ARGs by heavy metals. The effects of RL and Tw on ARGs and intI1 indicate that the addition of Tw was slightly more effective than RL after composting.