Low aeration rate during the cooling phase facilitated the removal of antibiotic resistance genes in the sludge and straw compost

Abstract

To evaluate the effect of aeration rate on microorganisms and antibiotic resistance genes (ARGs) in an aerobic composting system, co-composting experiments with varying aeration rates were conducted during the high-temperature and cooling phases of composting. The results showed that the content of ARGs in all treatment groups decreased by 1.2–4.2 logs at the end of composting. Furthermore, the low aeration rate treatment during the cooling phase (CAno group) was highly effective in reducing the risk of ARG dissemination. Compared with the control group, ten ARGs decreased by 0.04–1.13 logs, except for sul2, which increased by 0.02 logs. In the CAno group, denitrification slightly increased. Several ARGs associated with bacterial genera were evaluated as potential hosts for ARGs, such as Unspecified_Pseudomonadaceae and Acholeplasma. The CAno group exhibited the lowest abundance of these bacteria, contributing further to the reduction of ARGs in compost.