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Microbe-Mediated Degradation of Polyethylene and Release of Associated Pollutants under Simulated Dark Environments
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Landfills and deep ocean sediments are dark, oxygen-poor environments where plastic waste may sit for decades, yet little was known about what happens to it there. An 800-day experiment found that anaerobic bacteria slowly colonize and degrade polyethylene (PE), but in doing so they release massive numbers of nanoplastic particles—up to 430 billion per milliliter of leachate—along with phthalate chemical additives. Plastics buried for around seven years appeared most vulnerable to microbial attack. These findings reveal that landfills are not passive plastic storage sites but active generators of secondary nanoplastic and chemical pollution that can leach into surrounding environments.
Polyethylene (PE) dominates global packaging waste, yet its fate remains poorly understood in dark, anoxic environments such as ocean sediments and landfills, which represent important reservoirs for discarded plastics. In this study, 800-day microcosm experiments were performed with PE samples retrieved from an active landfill site with distinct landfill durations. Results demonstrated that anaerobic microbes slowly degrade PE while enhancing the release of secondary pollutants, such as nanoplastics (NPs) and phthalate esters (PAEs). Microbial colonization increased the surface roughness of PE samples and the abundance of oxygenated functional groups, driving oxidative chain scission, NP release (2.4-4.3 × 1011 particles mL-1 leachate), and PAE biodegradation. Logarithmic curves derived from an improved Polymer Aging Index revealed a midage acceleration window, with PE buried for 7 years being the most susceptible to microbial attack. PE-associated microbial communities were dominated by deterministic assembly processes, with functional taxa being the dominant drivers of PE aging, and PAE degraders exhibiting dual-threshold dynamics. Together, this study identifies a coupled oxidation-biodegradation-fragmentation feedbacks mechanism that governs the fate of PE in landfills, highlighting the dual microbial role in degrading PE and amplifying associated pollutant release.
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Biodegradation of polystyrene (PS) and polypropylene (PP) by deep-sea psychrophilic bacteria of Pseudoalteromonas in accompany with simultaneous release of microplastics and nanoplastics
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Researchers discovered that deep-sea bacteria from the genus Pseudoalteromonas can break down polystyrene and polypropylene plastics, though the process also releases smaller micro- and nanoplastic fragments. The bacteria were enriched over a year-long experiment at deep-sea conditions using plastic as their sole carbon source. The study suggests that while microbial degradation of ocean plastics is possible, it may simultaneously generate secondary nanoplastic pollution.
Aging-Driven Mobilization of Endogenous Phthalate Esters from Microplastics and the Ecotoxicity of PAEs toward Soil Microbiota and Plants.
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Lab tests showed microplastics release more phthalate chemicals when exposed to oxidation and mechanical wear than to mild acid conditions. Higher levels of these released chemicals reduced plant growth and germination by up to 91.4%, inhibited some soil and water microorganisms, and changed the makeup of soil bacterial communities.
Selective bacterial colonization processes on polyethylene waste samples in an abandoned landfill site
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Researchers examined polyethylene plastic waste from an abandoned landfill after more than 35 years of weathering, finding that each degraded plastic type hosted a unique community of bacteria that differed from neighboring plastics and from the surrounding soil. The most degraded plastics had bacterial communities most similar to the surrounding soil, suggesting that plastic breakdown gradually reduces the distinct ecological niche that plastics create for microbes.
Biodegradation of micro-polyethylene particles by bacterial colonization of a mixed microbial consortium isolated from a landfill site
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A bacterial consortium isolated from a municipal landfill, dominated by Bacillus and Paenibacillus species, was shown to reduce the dry weight of polyethylene microplastic particles by 14.7% and particle diameter by 22.8% after 60 days of incubation. The study provides evidence that landfill-adapted bacteria can biodegrade PE microplastics under mesophilic conditions.
Degradation of microplastics and the plastisphere bacteria in the acidogenic phase of simulated municipal solid waste landfilling
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Researchers simulated conditions inside a municipal solid waste landfill and found that different microplastic types (PE, PS, and PLA) aged and degraded at very different rates during the acidogenic leachate phase, with distinct microbial communities forming on each plastic type. This matters because landfills are both sources and sinks for microplastics, and understanding how plastics degrade there helps predict what eventually leaches into groundwater and surrounding soil.
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