Direct Evidence of Microplastic-Mediated Microbial Migration Across the River-Sea Transition via a Novel...

Area of Science:

• Environmental Science
• Microbiology
• Ecotoxicology

Background:

• Rivers transport significant microplastic (MP) pollution to oceans annually.
• Biofilm-covered MPs, known as the "plastisphere," may facilitate microbial transfer.
• Limited direct evidence exists on the impact of plastispheres on marine microbial communities.

Purpose of the Study:

• To directly evaluate the effects of microplastics (MPs) on marine microbial communities during the river-sea transition.
• To investigate the role of plastispheres in mediating microbial transfer and associated risks.

Main Methods:

• Combined field and laboratory experiments using microplastics incubated in freshwater for varying durations (0, 28, 140 days).
• Transferred incubated MPs to a simulated marine micro-ecosystem with a fresh seawater microbiome.
• Analyzed microbial community dynamics using metagenomic analysis over 1, 3, and 7 days of marine incubation.

Main Results:

• Long-term incubated plastispheres (140 days) rapidly altered marine community structure within 1 day, though this effect diminished by Day 7.
• The presence of 28-day and 140-day plastispheres consistently increased microbial species diversity.
• Plastispheres significantly elevated the abundance of antibiotic resistance genes (ARGs) and virulence factors (VFs), with effects persisting up to 7 days.
• Salt-tolerant, potentially pathogenic bacteria were detected on plastispheres, indicating their role as carriers.

Conclusions:

• Plastispheres act as vectors for microbial transfer, enhancing marine microbial diversity.
• Microplastics contribute to the spread of antibiotic resistance genes and virulence factors in marine environments.
• This research highlights the potential ecological and environmental risks associated with microplastic pollution.