Insight into the mechanism of alkyl polyglucose biosurfactants enhancing antibiotics resistance genes removal during biotransformation of waste activated sludge into medium-chain fatty acids

Abstract

Enhancing the biodegradability of waste activated sludge (WAS) based on environmentally friendly biosurfactants alkyl polyglucose (APG) to promote the recovery of medium-chain fatty acids (MCFAs) is a promising strategy. However, the effect and underlying mechanism of APG on antibiotic resistance genes (ARGs) removal during MCFAs production by WAS anaerobic fermentation are still unclear. This study found that APG significantly enhanced the removal of ARGs during the anaerobic fermentation to produce MCFAs, and the maximum removal efficiency of total ARGs was 95.64 % in 0.3 g APG/g TSS group, which was 46.31 % higher than the control group. The increase in extracellular lactate dehydrogenase, 16S rDNA and ARGs indicated that APG strengthened the lysis of ARGs hosts, thus suppressing the vertical transfer of ARGs caused by host proliferation. Furthermore, APG facilitated the decline in the abundance of mobile gene elements and two-component system genes, which was beneficial to reduce the horizontal transfer of ARGs. Microbial community and network analysis revealed that APG enriched functional microorganism and reduced potential ARGs hosts. Finally, partial least-squares path model analysis further demonstrated that the effectiveness of APG in ARGs removal was related to the restriction of ARGs transfer and change of bacterial community.