Insights into the role of extracellular polymeric substances (EPS) in the spread of antibiotic resistance genes

Antibiotic resistance genes (ARG) are prevalent in aquatic environments. Discharge from wastewater treatment plants is an important point source of ARG release into the environment. It has been reported that biological treatment processes may enhance rather than remove ARG because of their presence in sludge. Attenuation of ARG in biotechnological processes has been studied in depth, showing that many microorganisms can secrete complex extracellular polymeric substances (EPS). These EPS can serve as multifunctional elements of microbial communities, involving aspects, such as protection, structure, recognition, adhesion, and physiology. These aspects can influence the interaction between microbial cells and extracellular ARG, as well as the uptake of extracellular ARG by microbial cells, thus changing the transformative capability of extracellular ARG. However, it remains unclear whether EPS can affect horizontal ARG transfer, which is one of the main processes of ARG dissemination. In light of this knowledge gap, this review provides insight into the role of EPS in the transmission of ARGs; furthermore, the mechanism of ARG spread is analyzed, and the molecular compositions and functional properties of EPS are summarized; also, how EPS influence ARG mitigation is addressed, and factors impacting how EPS facilitate ARG during wastewater treatment are summarized. This review provides comprehensive insights into the role of EPS in controlling the transport and fate of ARG during biodegradation processes at the mechanistic level.