Decoding the microplastic Micro-interface: a complex Web of gene transfer and pathogenic threats in wastewater.

Area of Science:

• Environmental Microbiology
• Wastewater Treatment Technologies
• Public Health

Background:

• Microplastic micro-interfaces (MPMIs) in municipal wastewater treatment systems (MWTS) create unique niches for microbial communities (MGs) and potential pathogens (PPHs).
• These MPMIs can facilitate the horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs) and virulence factor genes (VFGs).
• The distribution and transfer dynamics of PPHs, ARGs, and VFGs within MPMIs remain largely uncharacterized.

Purpose of the Study:

• To investigate the distribution patterns of MGs, PPHs, ARGs, and VFGs across different microplastic types (PET, PE, PP) within MWTS.
• To elucidate the gene transfer events, particularly HGT of ARGs and VFGs, mediated by mobile genetic elements (MGEs) and PPHs within MPMIs.
• To assess the associated public health risks stemming from ARG and VFG metastasis within MPMI.

Main Methods:

• Utilized metagenomics to analyze three representative MPMIs (PET-MPMI, PE-MPMI, PP-MPMI) along a transverse gradient in MWTS.
• Quantified and analyzed the co-occurrence and connectivity of MGs, PPHs, ARGs, VFGs, and MGEs.
• Employed network analysis to determine centrality and diversity metrics for ARG hosts and gene interactions.

Main Results:

• Significant variations in MGs, PPHs, ARGs, VFGs, and MGEs were observed across transverse gradients and horizontal interfaces.
• MPMIs exhibited enhanced microbial and pathogen connectivity and robustness, with specific ARG hosts showing greater diversity.
• A complex and persistent coexistence of MGs, ARGs, and VFGs was found in MPMIs, increasing pathogenicity risk and accelerating ARG HGT via MGEs and PPHs.

Conclusions:

• MPMIs act as hotspots for microbial communities and pathogens, promoting the HGT of ARGs and VFGs.
• The structure of MPMIs facilitates gene co-occurrence and transfer, posing significant public health risks due to ARG and VFG metastasis.
• A conceptual framework was developed to understand gene dynamics and health implications within MPMIs.