[Composition Characteristics and Construction Mechanism of Microbial Community on Microplastic Surface in Typical...

Area of Science:

• Environmental microbiology
• Biogeochemistry
• Polymer science

Background:

• Microplastics are ubiquitous in the environment and host distinct microbial communities known as plastispheres.
• Redox conditions are crucial environmental factors influencing microbial community structure and function.
• Understanding how different microplastic types interact with microbial communities under varying redox conditions is vital for assessing their environmental fate.

Purpose of the Study:

• To investigate the impact of different redox environments on the microbial community composition and assembly mechanisms on three types of microplastics: PHA, PLA, and PVC.
• To compare the effects of microplastic type and redox environment on plastisphere microbial communities.
• To determine the relationship between microplastic degradability, redox conditions, and microbial community characteristics.

Main Methods:

• Microcosm experiments were conducted using sludge as inoculum.
• Three microplastic types (PHA, PLA, PVC) were incubated in five distinct redox environments (aerobic, nitrate reduction, iron oxide reduction, sulfate reduction, methane production).
• Microbial community composition was analyzed taxonomically and phylogenetically.

Main Results:

• Microplastic type influenced microbial communities by 18.94% (taxonomy) and 46.67% (phylogeny).
• Redox environment had a stronger influence, affecting 31.04% (taxonomy) and 90.00% (phylogeny) of the microbial communities.
• Microbial richness and diversity decreased on microplastics compared to sludge, with the most significant reduction on degradable PHA. Refractory PLA and PVC showed similar microbial communities.
• Dominant genera differed: *Anaerocolumna* on PHA, while *Clostridium_sensu_stricto_7* dominated PLA and PVC.
• Refractory microplastics enriched microbes involved in redox reactions, unlike degradable PHA.

Conclusions:

• Redox factors are primary drivers of plastisphere microbial community structure, more so than microplastic type.
• Refractory microplastics (PLA, PVC) selectively enrich characteristic microbes involved in redox reactions.
• Microplastics, particularly under specific redox conditions, have the potential to influence the rates of biogeochemical cycling.