Freeze-thaw aging and microbial colonization converts microplastics into nitrogen cycling hotspots

Area of Science:

• Environmental Science
• Microbiology
• Ecology

Background:

• Global warming increases freeze-thaw cycles (FTCs), impacting microbial processes.
• The combined effects of FTCs and microplastics (MPs) on microbial communities and nitrogen cycling are poorly understood.

Purpose of the Study:

• To investigate the synergistic effects of FTCs and MPs on microbial community assembly and nitrogen metabolism.
• To elucidate the co-regulatory mechanisms of FTCs and MPs on the plastisphere microbiome.

Main Methods:

• A microcosm experiment was conducted.
• Metagenomic sequencing and random forest modeling were integrated.
• Environmental aging of MPs and microbial community structure/function were analyzed.

Main Results:

• FTCs accelerated MP aging, creating favorable microhabitats for microbes.
• Combined FTCs and MPs increased microbial richness, diversity, and niche specialization.
• FTCs altered plastisphere nitrogen metabolism, enriching nitrite reductase genes and potentially increasing N₂O emissions.

Conclusions:

• FTCs transform MPs into metabolically active microhabitats.
• The interaction between FTCs and MPs significantly impacts microbial communities and nitrogen cycling.
• Findings provide insights into assessing emerging pollutants under climate change scenarios.