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Size- and polymer-dependent toxicity of microplastics on Achromobacter-mediated PCB biodegradation: Gene suppression, oxidative stress, and morphological responses
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Tiny plastic particles found everywhere in our environment may be making it harder for helpful bacteria to break down PCBs, toxic industrial chemicals still lingering in soil and water decades after being banned. The smaller the plastic pieces (like those 25 micrometers wide, smaller than a human hair), the more they stressed out these cleanup bacteria and shut down the genes they need to do their job. This matters because it suggests microplastic pollution could be secretly slowing down nature's ability to clean up other toxic chemicals, potentially leaving more harmful PCBs in our environment for longer.
The ubiquitous presence of microplastics (MPs) in polychlorinated biphenyl (PCB)-contaminated environments may hinder microbial bioremediation through adsorption and toxicity effects; however, their specific effects on PCB-degrading bacteria remain unclear. In this study, the effects of polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC), each at particle sizes of 25 μm and 250 μm, on the growth and Aroclor 1242-degrading capability of the resuscitated strain Achromobacter sp. HR2 were systematically evaluated. In addition, MP-induced alterations in the expression of functional genes, antioxidant enzyme activity, and morphological and physiological characteristics were assessed. The results revealed that MPs significantly inhibited microbial growth and PCB degradation in a size-dependent manner, with PS25 causing the greatest inhibition. Transcriptional analysis showed significant downregulation of key degradation genes (bphB, bphD, pobA, pcaGH, and pcaB) in MP-amended groups, with PS25 eliciting the most pronounced repression. MPs also induced elevated levels of intracellular reactive oxygen species and malondialdehyde, accompanied by enhanced activities of superoxide dismutase and catalase, indicating activation of the bacterial antioxidant defense system. Morphological and physiological disturbances were more pronounced with smaller (25 μm) MPs. This study provides valuable insights into the evaluation of microbial bioremediation performance in environments co-contaminated with MPs and PCBs.
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Researchers are using genomics and proteomics to identify and engineer microbes and enzymes capable of breaking down microplastics in the environment, a field that holds promise for biological cleanup of plastic pollution. Understanding which genes and proteins drive plastic degradation could lead to targeted bioremediation strategies for soils and waterways contaminated with persistent plastic fragments.
The influence of microplastics on the toxic effects and biodegradation of bisphenol A in the microalgae Chlorella pyrenoidosa
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Researchers discovered that polystyrene microplastics worsen the toxic effects of the common chemical bisphenol A (BPA) on green algae, suggesting that microplastics in aquatic environments can amplify the harm caused by other pollutants and may have cascading effects on aquatic food chains.
Microbial degradation of microplastics by enzymatic processes: a review
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Microorganisms including bacteria, fungi, and algae produce enzymes capable of degrading microplastics, offering a biologically safe remediation pathway that avoids secondary toxic byproducts. Advancing our understanding of specific enzymes and their degradation mechanisms could unlock scalable solutions for eliminating persistent microplastic contamination from marine and terrestrial environments.
Microplastic Pollution in Aquatic Environment: Ecotoxicological Effects and Bioremediation Prospects
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A comprehensive review examined the ecotoxicological effects of microplastics on aquatic organisms and assessed the potential of bioremediation strategies—including microorganisms and plants—to remove microplastics from contaminated water. As chemical and physical removal methods remain costly and incomplete, biological approaches offer promising complementary tools for reducing the aquatic microplastic burden that threatens both ecosystems and human health through contaminated seafood.
Biodegradation of Microplastics by Microbes
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Researchers examined how microplastic-degrading bacteria break down polymer structures by secreting hydrolytic extracellular enzymes including lipase, keratinase, and cellulases, providing foundational insight into the enzymatic pathways that underpin microbial biodegradation of plastic particles.
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