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Biodegradability of microplastics reshapes surface biofilm microbial community structure and nitrogen cycling functions in aquatic environments
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Researchers compared how biodegradable (PLA) and non-biodegradable (polyethylene and PVC) microplastics affect the microbial communities that form on their surfaces in aquatic environments, finding substantial differences in which bacteria colonized each plastic type and how they processed nitrogen. PLA supported communities rich in nitrogen-cycling bacteria, while PVC and polyethylene enriched different microbial groups associated with pollutant degradation. The study suggests that the push toward biodegradable plastics will change — not just reduce — the ecological effects of microplastics in rivers and lakes.
Environmental impacts of microplastics (MPs) in aquatic ecosystems have been extensively studied, limited attention has been given to how their material types affect surface biofilm development and related nutrient cycling. This experimental study involving three types of MPs biodegradable polylactic acid (PLA), non-biodegradable polyethylene (PE), and polyvinyl chloride (PVC) revealed that the PLA surface bioflims had a higher content of chlorophyll a (Chl a), and there are significant differences in the microbial community structure among the three groups of MPs. The PLA group enriched Niveispirillum and Flavobacterium, which are involved in the nitrogen cycle, and were positively associated with increased microbial diversity and community structural shifts at day 55. In contrast, the PE and PVC groups enriched Sediminibacterium, a genus with pollutant-degradation capabilities. Analysis of nitrogen cycling genes revealed that the PLA group had consistently high levels of the nitrite reductase gene (nirS) while the PVC group showed a significant increase in the copper-containing nitrite reductase gene (nirK) during the mid-stage of the experiment. Functional prediction analysis also revealed that PLA group showed enrichment in energy metabolism pathways such as glycolysis, indicating that surface microbes preferentially utilize sugars as carbon and energy sources. In contrast, the PVC group showed higher reliance on amino acid metabolism, with enriched biosynthesis pathways of L-tryptophan and L-ornithine. The PE group had strong organic pollutant degradation, as surface microbes adapt to hydrophobic conditions by decomposing complex organics. Our results reveal that biodegradable PLA and non-biodegradable PE/PVC exert divergent effects on the development and ecological functions of surface biofilms, highlighting the key role of MP biodegradability in mediating these outcomes.
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Insights into soil microbial assemblages and nitrogen cycling function responses to conventional and biodegradable microplastics
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Researchers compared how biodegradable polylactic acid and conventional PVC microplastics affect soil bacteria and nitrogen cycling processes. They found that both types of microplastics altered microbial communities, but biodegradable plastics had distinct effects on nitrogen-processing bacteria and did not simply behave as a harmless alternative. The study suggests that switching to biodegradable plastics may change rather than eliminate the impact of microplastic contamination on soil health.
Effects of microplastics on nitrogen and phosphorus cycles and microbial communities in sediments
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Researchers found that PVC, PLA, and polypropylene microplastics altered nitrogen and phosphorus cycling in freshwater sediments by shifting microbial community composition, with effects varying by polymer type and biodegradability.
Distinct riverine plastispheres and microplastic-specific community complexity in the near-bottom benthic habitat under natural hydrological conditions
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Scientists found that different types of plastic litter sitting at the bottom of rivers each grow their own unique community of microbes, sort of like tiny biofilm "neighborhoods" that vary by plastic type. Interestingly, so-called "biodegradable" plastics (PLA and PHA) hosted different microbes than regular plastics like PET and PVC, including some that support nitrogen cycling in the environment — but this doesn't necessarily mean they break down faster or safer. This matters because these microbial communities can affect how quickly plastics degrade, potentially into smaller microplastic particles that end up in water we drink and
Distinct influence of conventional and biodegradable microplastics on microbe-driving nitrogen cycling processes in soils and plastispheres as evaluated by metagenomic analysis
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Researchers compared how conventional polyethylene and biodegradable microplastics affect nitrogen cycling by soil microbes. They found that biodegradable microplastics caused stronger changes to microbial communities and nitrogen processing pathways than conventional plastics, particularly by enriching certain bacteria on their surfaces. The study suggests that even biodegradable plastic mulch alternatives may significantly alter soil nutrient cycling in agricultural settings.
Microplastic exposure drives divergent assembly mechanisms in riverine microorganisms: Poly(butylene adipate-co-terephthalate) triggers metabolic shifts vs polyethylene-enhanced network complexity
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Researchers compared how conventional polyethylene and biodegradable PBAT microplastics affect microbial communities in river water over 60 days. They found that both types significantly altered bacterial diversity, but through different mechanisms: PBAT triggered metabolic shifts in microorganisms while polyethylene increased the complexity of microbial networks. The study suggests that even biodegradable plastics can meaningfully disrupt aquatic microbial ecosystems.
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When a large batch of papers lands in the Atlas, we read through it and send a short write-up of what stood out.