Antibiotic resistance at environmental multi-media interfaces through integrated genotype and phenotype analysis.

Antibiotic resistance is currently an unfolding global crisis threatening human health worldwide. While antibiotic resistance genes (ARGs) are known to be pervasive in environmental media, the occurrence of antibiotic resistance at interfaces between two or more adjacent media is largely unknown. Here, we designed a microcosm study to simulate plastic pollution in paddy soil and used a novel method, stimulated Raman scattering coupled with deuterium oxide (D₂O) labelling, to compare the antibiotic resistance in a single medium with that at the interface of multiple environmental media (plastic, soil, water). Results revealed that the involvement of more types of environmental media at interfaces led to a higher proportion of active resistant bacteria. Genotypic analysis showed that ARGs (especially high-risk ARGs) and mobile genetic elements (MGEs) were all highly enriched at the interfaces. This enrichment was further enhanced by the co-stress of heavy metal (arsenic) and antibiotic (ciprofloxacin). Our study is the first to apply stimulated Raman scattering to elucidate antibiotic resistance at environmental interfaces and reveals novel pathway of antibiotic resistance dissemination in the environment and overlooked risks to human health.