Microbial Inoculant-Driven Degradation of Microplastics Associated With Garbage Environment and Assessment of Degradation Product Toxicity.

Cardiovascular disease (CVD is the leading non-communicable cause of death accounting for approximately 30% of all deaths worldwide. Recently, different natural and chemical substances including microplastics which are plastic particles with a diameter less than 5 mm have been implicated in causing damage to organs of the body including cardiovascular health and diabetes. Aim: This study was conducted to evaluate the effects of chronic exposure to microplastics in drinking water on some biochemical parameters in albino rats. Methodology: A total of Thirty-seven (37) albino rats weighing 130-150g were used for this study. Polyethylene terephthalate (PET) microplastics pellets were obtained, crushed, dissolved in water and filtered before use. Pilot study was carried out to determine the LD50 of PET microplastic administered orally using the Lorke’s method of pilot toxicity testing. After allowing fourteen (14) days for acclimatization, the rats were randomly assigned into 5 groups with 5 rats in each group. The PET treatment was administered orally for 3 months. 40mg/kg, 80mg/kg and 120mg/kg PET microplastic were given to animals in groups 2, 3, and 4 respectively. Group 5 received water exposed to sunlight between 8am to 4pm daily for 30 days in PET containers while group 1 was normal control receiving food and water only. After the duration of treatments, blood samples were collected for analysis of total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL) and glycated haemoglobin (HBA1c) using colorimetric methods while the LDL cholesterol levels were calculated using the Friedwald’s equation. Atherogenic indices such as Castelli Risk Index I (CRI-I), Castelli Risk Index II (CRI-II) and Atherogenic Coefficient (AC) were also calculated from the lipid profile values. Fasting blood glucose (FBG) were analysed using glucose oxidase method while Cardiac troponin I (cTn-I) and TNF a were evaluated using ELISA method. Statistical analysis was computed using GraphPad Prism Software Version 9.0.0 (121), San Diego, CA. Data obtained from this study were presented as mean ± SD. Statistical comparison between groups were done using one-way ANOVA, while Tukeys multiple comparison were used to obtain specific significant differences among the various groups. Differences were considered significant at P<0.05. Results: Results obtained revealed the LD50 of PET administered orally to be 122.27mg/kg. There was a significant increase in levels of cardiac troponin I, Tumor Necrosis Factor Alpha, total cholesterol, LDL cholesterol, CRI-I, CRI-II, AC, fasting blood glucose and glycated haemoglobin in the PET treated groups compared to the control at (p<0.05). Similarly, the mean cardiac troponin I and TNF a, levels in the group treated with bottled water exposed to sunlight were significantly higher than in the control group but significantly lower than in the PET-treated groups at p<0.05. Conclusions: The findings from this study demonstrate that chronic exposure to PET microplastics induces significant alterations in these biochemical biomarkers in albino rats suggesting that PET microplastics may contribute to inflammation, cardiovascular disorders, and impaired glucose metabolism, which may increase the risk of insulin resistance and diabetes, thus, emphasizing the potential health risks associated with PET microplastic ingestion.

IntroductionEmerging contaminants such as microplastics (MPs) and antibiotics pose increasing environmental and public health risks due to their persistence and incomplete removal by wastewater treatment processes. MPs can act as vectors for antibiotics, facilitating their environmental spreading and supporting biofilm formation, which can enhance horizontal gene transfer and antibiotic resistance. This study investigates the combined effects of ciprofloxacin (CIP) and polyethylene terephthalate (PET) MPs on microbiota in alpine spring water (SW) sourced from a rock glacier.MethodsFour experimental scenarios (Control, CIP, PET, CIP + PET) were established to assess the sorption dynamics of CIP onto PET particles and the consequent microbial responses. A multidisciplinary analytical approach combining ultra-performance liquid chromatography, microscopy, quantitative PCR, and metabarcoding was applied.ResultsCIP exhibited progressive sorption onto PET, accompanied by a time-dependent increase in biofilm formation, most pronounced in the CIP + PET condition. qPCR revealed elevated copy numbers of resistance genes qnrA and qnrB in CIP + PET, suggesting synergistic effects between antibiotics and MPs in promoting resistance. CIP was the dominant driver of microbial compositional shifts, favoring known CIP-degrading taxa. A shared core microbiome of 216 amplicon sequence variants was detected across all conditions, but specific taxa were differentially enriched under varying exposures. The combined CIP + PET test induced the strongest community shifts, while CIP alone shared fewer taxa with controls, indicating selective pressure for resistant microorganisms like Achromobacter. PET MPs also shaped distinct microbial assemblages, possibly by offering niches favoring biofilm-associated genera such as Luteolibacter. Biodiversity metrics showed highest richness and evenness in CIP-free conditions (Control and PET), while CIP significantly reduced alpha diversity, favoring resistant taxa, as confirmed by NMDS and lower Shannon and Simpson indices. Effects of MPs were still noticeable.ConclusionThese findings demonstrate the disruptive effects of CIP on alpine freshwater microbial communities and highlight the additional, though more moderate, influence of MPs. The combined presence of MPs and antibiotics may exacerbate resistance spreading by enhancing persistence and providing favorable conditions for resistant biofilms. A mechanistic understanding of these interactions is essential for accurate risk assessment and the development of effective mitigation strategies in alpine and other vulnerable freshwater ecosystems.

Enhanced degradation of polyethylene terephthalate (PET) microplastics by an engineered Stenotrophomonas pavanii in the presence of biofilm

Plastic food? Energy compensation of zebrafish (Danio rerio) after long-term exposure to polylactic acid biomicroplastics

Polyethylene terephthalate (PET) microplastics constitute a significant portion of plastic pollution in the environment and pose substantial environmental challenges. In this study, the effectiveness of the Fenton process and post-oxidation coagulation for the removal of non-weathered and UV-weathered PET microplastics (PET MPs) were investigated. A response surface methodology was used to investigate the interplay between PET concentration and ferrous ion (Fe2+) concentration. The models revealed an intricate interplay between these variables, highlighting the need for a balanced system for optimal PET MP removal. For non-weathered PET, the simultaneous increase in the concentrations of both PET microplastics and Fe2+ was found to enhance the removal efficiency. However, this synergistic effect was not observed in UV-weathered PET, which also demonstrated a more pronounced effect from the Fe2+ concentration. The statistical analysis provided a strong basis for the validity of the models. X-ray photoemission spectroscopy (XPS) further elucidated the mechanisms behind these findings, revealing that UV weathering results in surface changes, which facilitate hydroxyl radical oxidation. These findings underline the complexity of the Fenton process in PET microplastic removal and the different behavior of non-weathered and UV-weathered microplastics. This has significant implications for tailoring remediation strategies and underscores the importance of considering environmental weathering in these strategies.

There is a lack of knowledge regarding the mechanisms that induce microplastic fragmentation and degradation within the environment. This research aimed to quantify the combined degradative effects that mechanical abrasion in conjunction with photo-oxidation and hydrolysis, have on polyethylene terephthalate (PET) microplastics. To accomplish this, common routes of degradation were evaluated. Degradation was assessed using three indices indicative of polymer degradation: Carbonyl Index (CI), Carbon-to-Oxygen Index (COI), and Hydroxyl Index (HI). This study assessed the effects that mechanical abrasion (MA), photo-oxidation, and various simulated environmental conditions: aqueous (Aq), aqueous + ultraviolet (UV), and UV only within two distinct settings (lab vs outdoor) have on PET microplastic degradation. Photo-oxidation exposure across a 60-d period induced significant degradation on PET microplastics resulting in a 1-22% increase in carbonyl groups across all treatments except UV and Aq. + UV Chamber (MA). A 6-214% increase in hydroxyl groups across all treatments. A 1-10% decrease in carbon-to-oxygen groups in all treatments except the Chamber Aqueous and Outdoor UV (MA). Mechanical abrasion seemed to accelerate this degradation in combination with both UV and aqueous treatments. Using simulated environmental conditions to induce degradation upon PET microplastics, in both lab and simulated environmentally relevant settings, revealed that the combined effects of hydrolysis and photo-oxidation can accelerate the process, especially in conjunction with mechanical abrasion. The novel findings presented here provide insight into the complex relationship between various polymer degradation pathways and the effects that mechanical abrasion can have on them, while also providing additional data for an understudied yet prevalent plastic polymer.

The widespread use and improper disposal of plastics in the environment lead to microplastic (MP) pollution. Polyethylene terephthalate (PET) plastics are widely used as single-use plastics, and the mass use of these plastics is contaminating aquatic and terrestrial environments. The transportation of those plastic fragments on agricultural land increases the risk to crop production and food safety. Therefore, the study aimed to evaluate the effect of polyethylene terephthalate microplastics (PET-MPs) on plant growth, nutrient uptake, and physiological stress responses. A short-term effect of PET-MPs (0.1 g/L) on plant growth was assessed using radish (Raphanus sativus) and carrot (Daucus carota var. sativa) grown in half-strength Hoagland solution for one week. PET-MPs did not significantly affect plant biomass and nutrient uptake by plants. Micronutrients such as Cu, Fe, Mn, and Zn were mostly increased in roots and decreased in shoot samples of both plants with PET-MP treatment compared to the control. Although short-term exposure of plants to PET-MPs did not significantly affect plant biomass and nutrient uptake, a significant difference was observed in the physiological stress responses. Chlorophyll a and b contents were significantly (p < 0.05) decreased in radish leaves after PET-MP treatment. Malondialdehyde (MDA) content in the leaves of radish plants significantly increased, indicating that the plant was facing abiotic stress in PET-MP treatment. This study advances understanding of MP-induced phytotoxicity and highlights its potential implications for food safety in agroecosystems.

Interactive effects between sinking polyethylene terephthalate (PET) microplastics deriving from water bottles and a benthic grazer

Quantitative analysis of polyethylene terephthalate and polycarbonate microplastics in sediment collected from South Korea, Japan and the USA

This study evaluated the ability of the red microalga Porphyridium cruentum in removing polyethylene terephthalate (PET) microplastics (MPs) from aquatic systems through a hetero‐aggregation mechanism mediated by exopolysaccharides (EPS). Results showed that PET MPs exposure to microalgae at concentrations of 100, 200, and 300 mg/L for 30 days notably reduced microalgae growth at higher concentrations. Conversely, increased PET MPs concentration increased EPS production by microalgae as a defense response to oxidative stress. The highest EPS production was obtained at a 300 mg/L PET MPs exposure, concentration of 4.349 g/L. FTIR analysis showed EPS was rich in negatively charged carboxyl and sulfate groups, electrostatically interacting with positively charged PET MPs, forming stable flocculating hetero‐aggregates. The removal efficiency of PET MPs reached 95.8%–97.5%, with the highest efficiency obtained at a concentration of 200 mg/L PET MPs, demonstrating the effectiveness of P. cruentum in removing PET MPs from water environment. SEM analysis confirmed the formation of a solid EPS matrix encasing the MPs particles and the absence of markedly structural changes in the EPS post‐interaction confirmed through FTIR. These findings underscore the potential of microalgae as an eco‐friendly and energy‐efficient biological solution for MPs remediation in aquatic environments.

Toxic effects of fragmented polyethylene terephthalate particles on the marine rotifer Brachionus koreanus: Based on ingestion and egestion assay, in vivo toxicity test, and multi-omics analysis

Background: The efficiency of vermicomposting in reducing antibiotic resistance genes (ARGs) in dairy manure may be compromised by co-pollutants like arsenic (As) and microplastics. Specifically, plasmids serving as carriers and vectors of ARGs were largely distributed in this process. However, the impact of As and microplastics on plasmids carrying ARGs during vermicomposting is largely unknown. Methods: This study utilized a controlled experimental design and applied plasmid metagenomics to investigate the individual and combined effects of As and polyethylene terephthalate (PET) microplastics on plasmid-mediated ARG dynamics during vermicomposting. Results: We found that vermicomposting alone mainly enriched non-mobilizable plasmids, while PET microplastics selectively promoted conjugative and mobilizable plasmids, whereas As significantly increased all plasmid types. Moreover, both PET or As alone and combined exposure (PET and As) increased total ARG abundance, with their combination inducing synergistic ARG enrichment despite unchanged total plasmid abundance. Furthermore, co-occurrence network analysis combined with ARGs/plasmid ratio assessments demonstrated that As influences ARGs through co-selective pressure by enriching ARGs co-localized with As resistance genes (e.g., the ars operon) on plasmids while simultaneously promoting horizontal gene transfer (HGT) via activation of oxidative stress and SOS response pathways. In contrast, PET primarily facilitates ARG dissemination through a “metabolism-resistance” coupling strategy by enriching colonizing bacteria with PET-degrading capacity. Their co-exposure formed As-enrichment hotspots on PET microplastic surfaces, functioning as a “super-mixer” that selectively screened for superbugs carrying potent resistance mechanisms (e.g., blaOXA-50 and mdtB/mdtE). Conclusions: This study provides the first plasmidome-level evidence of synergistic ARG propagation by As and PET microplastics during vermicomposting, highlighting mobile genetic elements’ critical role in co-pollutant risk assessments.

Polyethylene terephthalate microplastics affect hydrogen production from alkaline anaerobic fermentation of waste activated sludge through altering viability and activity of anaerobic microorganisms

The use of plastic bakeware is a potential source of human exposure to microplastics (MPs). However, characterizing MPs remains a challenge. This study aims to employ optical photothermal infrared (O-PTIR) and quantum cascade laser infrared (QCL-IR) technology to characterise polyethylene terephthalate (PET) MPs shed from PET bakeware during the baking process. The bakeware, filled with ultrapure water, underwent baking cycles at 220 °C for 20 min, 60 min, and three consecutive cycles of 60 min each. Subsequently, particles present in the ultrapure water were collected using an Al2O3 filter. O-PTIR and QCL-IR were used to characterise PET MPs collected from the filtration. Analysis revealed that QCL-IR spectra exhibited broader absorption peaks, compared to O-PTIR. Notably, MP spectra obtained from both techniques displayed common absorption peaks around 1119, 1623, 1341 and 1725 cm−1. The dominant size of PET MPs detected by O-PTIR and QCL-IR was 1–3 μm and 5–20 μm, respectively. The quantity of identified PET MPs using O-PTIR was 18 times greater than that with QCL-IR, which was attributed to variations in spatial resolution, sampling methods for spectra collection, and data analysis employed by the two methods. Importantly, findings from both techniques highlighted a notably large quantity of MPs released from PET bakeware, particularly evident after 3 cycles of 60 min of baking, suggesting a substantial increase in the potential ingestion of MPs, especially in scenarios involving extended baking durations. The research outcomes will guide consumers on minimizing the intake of microplastics by using PET bakeware for shorter baking time. Additionally, the study will yield valuable insights into the application of O-PTIR and QCL-IR for MPs detection, potentially inspiring advancements in MPs detection methodologies through cutting-edge technologies.

Microplastics (MPs) raise environmental concerns. However, their effects on the ruminal-gastro-intestinal system have not yet been studied. This study aims to investigate the effects of polyethylene terephthalate (PET) MPs on the ability of the ruminal-gastro-intestinal system to degrade and digest mixed hay. Using a three-step in vitro ruminal-gastro-intestinal incubation system, PET MPs were introduced at concentrations of 0, 5, 10, and 15 g/L in ruminal and gastro-intestinal solutions. Ruminal fluid was collected from three 16-month-old Piedmontese bulls. The experiment was conducted on three mixed hays and was repeated three times, with triplicate incubations in each run. The results reveal that PET MPs reduced the degradability and digestibility of crude protein. Specifically, crude protein degradation was reduced by 9% at medium and 16% at high PET MP concentrations in the ruminal phase, while the crude protein digestibility of undegraded crude protein was reduced by 8% at the lowest PET MPs concentration in the gastro-intestinal tract. Additionally, PET MPs reduced the degradation of neutral detergent fiber at medium and high PET MP concentrations in the ruminal phase by 9% and 13%, respectively. These results highlight the risks of PET MPs contamination on ruminal-gastro-intestinal functions and underscore the urgent need to mitigate MPs contamination in the livestock sector.