The increasing and simultaneous pollution of plastic debris and antibiotic resistance in aquatic environments makes plastisphere a great health concern. However, the development process of antibiotic resistome in the plastisphere is largely unknown, impeding risk assessment associated with plastics. Here, we profiled the temporal dynamics of antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and microbial composition in the plastisphere from initial microbial colonization to biofilm formation in urban water. A total of 82 ARGs, 12 MGEs, and 63 bacterial pathogens were detected in the plastisphere and categorized as the pioneering, intermediate, and persistent ones. The high number of five MGEs and six ARGs persistently detected in the whole microbial colonization process was regarded as a major concern because of their potential role in disseminating antibiotic resistance. In addition to genomic analysis, D2O-labeled single-cell Raman spectroscopy was employed to interrogate the ecophysiology of plastisphere in a culture-independent way and demonstrated that the plastisphere was inherently more tolerant to antibiotics than bacterioplankton. Finally, by combining persistent MGEs, intensified colonization of pathogenic bacteria, increased tolerance to antibiotic, and potential trophic transfer into a holistic risk analysis, the plastisphere was indicated to constitute a hot spot to acquire and spread antibiotic resistance and impose a long-term risk to ecosystems and human health. These findings provide important insights into the antibiotic resistome and ecological risk of the plastisphere and highlight the necessity for comprehensive surveillance of plastisphere.
Single-cell Raman spectroscopy combined with heavy water revealing the phenotypic antibiotic tolerance of the plastisphere biofilm and planktonic bacteria under CIP treatment. (A) Schematic representation of the single-cell Raman-D2O method for assessing bacterial metabolic activity. (B) Typical single-cell Raman spectra of deuterium-labeled and unlabeled bacteria. (C) Distribution quartiles of C–D ratios measured from around 100 randomly selected single cells in the plastisphere or bacterioplankton. Each point is a measurement of one single cell. The red horizontal line at 3.98% C–D ratios shows the threshold for detection. It was defined as the mean + 3 SD of C–D ratios from randomly selected bacteria incubated without heavy water.
