Promotion of microplastic degradation on the conjugative transfer of antibiotic resistance genes in the gut of macrobenthic invertebrates

Microplastics and antibiotic resistance genes are two new pollutants in water environments, and they have potential risks to human health and ecological safety. On the basis of the accumulation of pollutants and microorganisms in sediment, macrobenthic invertebrates are considered as potential practitioners of microplastic degradation and antibiotic resistance gene (ARG) transfer. However, whether microplastic degradation can affect ARG transfer in aquatic environments, especially in the gut of macrobenthic invertebrates, remains unclear. In this study, we demonstrated that microplastics including polyethylene terephthalate (PET), polyvinyl chloride(PVC), polyamide (PA), polystyrene (PS), polypropylene (PP), polyethylene (PE), and polyurethane (PU), and ARGs including tetA , sul1 , sul2 , and sul3 were widely distributed in sediment and benthic invertebrates in Nansi lake. The distribution of ARGs was related to the number and size of microplastic particles. In particular, it was found for the first time that the content of ARGs corresponding to individual particles was linearly and negatively correlated with the size of microplastics. The results of animal feeding experiments showed that microplastic degradation in the gut of Chironomidae larvae could promote the conjugative transfer of ARGs. The underlying molecular mechanism was SOS response. This study provides a new method for the analysis of the interaction effect of multiple pollutants in freshwater environments. • It is found for the first time that the content of ARGs corresponding to individual particles was linearly and negatively correlated with the size of microplastics indicated by macrobenthic invertebrates. • In addition to the microplastics themselves, the degradation process of microplastics has a strong promotion effect on ARG transfer. • SOS response was the underlying molecular mechanism of the promotion effect of microplastic degradation on ARG transfer.