Microbial degradation and other environmental aspects of microplastics/plastics

Microplastics removal from stormwater runoff by bioretention cells: A review

Microplastics (MPs), as a new category of environmental pollutant, have been the hotspot of eco-friendly issues nowadays. Studies based on the aging process, the migration pattern of MPs in runoff rainwater, and the use of bioretention cells to remove MPs from runoff rainwater are beginning to attract widespread attention. This review analyses the migration patterns of MPs in rainwater runoff through their sources, structure and characteristics. The mechanism of removing MPs from runoff stormwater, the purification efficiency of different fillers and their influencing factors, and the accumulation, fate, and aging of MPs in bioretention cells are described. Furthermore, the hazards of MP accumulation on the performance of bioretention cells are summarised. Future directions for removing MPs in bioretention cells are proposed: (1) research on MPs smaller than 100 µm; (2) influence of MPs aging process on bioretention cells; (3) exploration of more effective fillers to enhance their removal efficiency; (4) research on synergistic removal mechanism of MPs and other pollution.

Unveiling gut microbiota and metabolic functions contributed to polyvinyl chloride degradation in Spodoptera frugiperda larvae

The accumulation of synthetic plastic waste, particularly polyvinyl chloride (PVC), threatens ecosystems globally. While microbial biodegradation represents a sustainable solution, limited effective PVC-degrading microbial bioresources have been identified. Here, we investigated the gut microbiota of Spodoptera frugiperda larvae, revealing a consistent microbial profile dominated by Enterococcus in both gut contents and tissues. PVC film feeding induced significant microbiota shifts, with functional parallels to PVC powder-fed Tenebrio molitor larvae despite taxonomic divergence. Through enzyme-centric analysis, we found an Enterococcus casseliflavus strain from the gut of S. frugiperda larvae could encode a NAD-dependent oxidoreductase that directly dechlorinates additive-free PVC, representing the first case of enzymatic polymer dechlorination. This enzyme reduced PVC molecular weight (Mn: 12.02 %; Mw: 14.07 %) and notably liberated chloride ions (6.48 mg/L with NADH as a co-factor). Our findings demonstrate the PVC-degrading capacity of S. frugiperda gut microbiota and reveal its dechlorination mechanism, offering an enzymatic candidate for developing novel biocatalysts and engineered microbial strains for enhanced biodegradation. By unravelling insect-associated microbes and enzymes, this work lays a theoretical foundation for their application potentials in sustainable PVC wastes upcycling and microplastic remediation.

Microplastics under siege: Biofilm-forming marine bacteria from the microplastisphere and their role in plastic degradation

Microplastics, a complex category of pollutants containing microorganisms and toxins, pose a significant threat to ecosystems, affecting both biotic and abiotic elements. The plastisphere's bacterial community differs significantly from nearby habitats, suggesting they may significantly contribute to the degradation of plastic waste in the ocean. This study evaluated the diversity of culturable bacterial populations attached to the microplastics in the coastal zones of the A&N Islands and their potential for plastic degradation. Three A&N Islands beaches were surveyed for microplastics. Low-density polyethylene (LDPE) was the most abundant polymer found, followed by Acryl fibre, polyisoprene etc. A total of 24 bacterial isolates were chosen based on their morphological traits and underwent the initial screening processes. With the highest degrading activity (10.79 %), NIOT-MP-52 produced noteworthy results. NIOT-MP-25 (5.07 %), NIOT-MP-43 (3.78 %), NIOT-MP-61 (3.51 %), and NIOT-MP-82 (3.36 %) were the next most active strains. Strain NIOT-MP-52, selected for its superior degradation efficiency, underwent further screening and analysis using FT-IR, SEM, AFM, and DSC. Variations in infrared spectra indicated the breakdown of LDPE while SEM and AFM analyses showed bacterial attachment, roughness, grooves, holes, and pits on the LDPE surface. DSC provided thermal analysis based on the biodegradation potential of the bacterial strain targeting LDPE sheets. These findings highlight the ability of marine bacteria to efficiently degrade microplastics and utilize plastics as an energy source, emphasizing their importance in future plastic waste management.

Microplastics in Agricultural Soils: Sources, Fate, and Interactions with Other Contaminants

Microplastics (MPs) are recognized as emerging soil contaminants. However, the potential risks of MPs to agroecosystems have not been fully revealed, especially the compound toxic effects of MPs with co-existing organic or inorganic pollutants (OPs/IPs) in agricultural fields. In this study, we quantified the contributions of different agronomic practices to the sources of MPs in soil and highlighted the important influences of long-term tillage and fertilization on the migration and aging of MPs in agricultural fields. In addition, the antagonistic and synergistic interactions between MPs and OPs/IPs in soil were explored. We emphasized that the degree of adsorption of MPs and soil particles to OPs/IPs is a key determinant of the co-toxicity of those contaminants in soil. Finally, several directions for future research are proposed, and these knowledge gaps provide an important basis for understanding the contamination process of MPs in agricultural soils.

Mitigating microplastic-induced organ Damage: Mechanistic insights from the microplastic-macrophage axes

We live in a world increasingly dominated by plastic, leading to the generation of microplastic particles that pose significant global health concerns. Microplastics can enter the body via ingestion, inhalation, and direct contact, accumulating in various tissues and potentially causing harm. Despite this, the specific cellular mechanisms and signaling pathways involved remain poorly understood. Macrophages are essential in absorbing, distributing, and eliminating microplastics, playing a key role in the body's defense mechanisms. Recent evidence highlights oxidative stress signaling as a key pathway in microplastic-induced macrophage dysfunction. The accumulation of microplastics generates reactive oxygen species (ROS), disrupting normal macrophage functions and exacerbating inflammation and organ damage. This review serves as the first comprehensive examination of the interplay between microplastics, macrophages, and oxidative stress. It discusses how oxidative stress mediates macrophage responses to microplastics and explores the interactions with gut microbiota. Additionally, it reviews the organ damage resulting from alterations in macrophage function mediated by microplastics and offers a novel perspective on the defense, assessment, and treatment of microplastic-induced harm from the viewpoint of macrophages.

Enzymatic degradation of PET by hydrolase from Brucella intermedia IITR130 and its genomic insights

Plastic pollution, particularly from polyethylene terephthalate (PET), has become a significant environmental concern, necessitating innovative and sustainable degradation strategies. The present study provides valuable perspectives on the genomic and functional characteristics of Brucella intermedia IITR130, a bacterium capable of degrading PET. Hybrid genome sequencing of IITR130 resulted in identification of two chromosomes combining 4.59 Mbp size. Genomic annotation revealed occurrence of key enzymes involved in the PET sheet biodegradation pathway, including hydrolases, ring hydroxylating dioxygenases, protocatechuate 3,4 dioxygenases, genes for metabolism of several other natural and synthetic plastic. A hydrolase gene Hy1 of 24 kDa, was identified, expressed, and characterized, demonstrating an optimal catalytic activity at 37 °C and pH 8.5. Scanning electron microscopy (SEM) and fourier-transform infrared spectroscopy (FTIR) confirmed substantial degradation of PET surfaces treated with Hy1 protein, resulted in surface erosion, crack formation, and functional group modifications in the range 2150-2550 cm⁻1 and 2950-3350 cm⁻1 suggestive of O=C=O stretching and O-H stretching respectively. Monomethyl terephthalate (MMT) and terephthalic acid (TPA) were identified as PET degradation metabolites formed by strain IITR130. Fluorescence quenching showed higher substrate affinity for bis(2-hydroxyethyl) terephthalate (BHET) (Kd = 148.2) than terephthalic acid (TPA) (Kd = 674). Moreover, phylogenetic analysis of Hy1 protein revealed that Hy1 containing conserved catalytic triad (Ser108, His188, Asp155) belonging to the family III of hydrolase enzyme sharing a clade with PET degrading hydrolase PETase from Ideonella sakaiensis. These results demonstrate the potential of B. intermedia IITR130 as an efficient biocatalyst for PET biodegradation which could be exploited appropriately for plastic waste management.

Responses of natural plastisphere community and zooplankton to microplastic pollution: a review on novel remediation strategies

The ubiquitous presence of microplastics (MP) in different environments has been well documented. Microplastic contamination has rapidly become a serious environmental issue, threatening marine ecosystems and human health. MP has been reported to accumulate organic pollutants associated with various microbial communities. The MP hazard is specifically serious in urban lakes, near-shore beaches, and benthic sediments. To prevent the further spread of MP and mitigate the increasing level of MP contamination, along with its associated environmental and economic concerns, it is essential to address mitigation strategies and their negative impacts. Contributed by low degradability, hydrophobicity, and sorption potential, the plastic surface acts as an important substrate colonized by several microorganisms known as the plastisphere community. Adaptive responses of the plastisphere community, MP ingestion, and surface modifications by the zooplankton provide insight into novel remediation strategies based on integrated natural community-level approaches. Zooplankton studies are extensive and encompass assessments of their abundance, biomass, distribution, and DNA meta-barcoding. Additionally, zooplankton has been utilized as an indicator in various freshwater environmental policies. Overall, employing zooplankton as an indicator in environmental policies is a vital tool for assessing the health of aquatic ecosystems and can assist in guiding management and conservation efforts. This review summarizes (i) the current literature on the estimation of MP distribution in aquatic environments, (ii) the effects of MP accumulation on the environment and its inhabitants, i.e., the interactions with marine microbiota,, (iii) addresses the bioremediation strategies with an emphasis on microbial degradation, ecological functioning and adaptive responses of marine microbes and finally, (iv) the directions of further research aiming to in situ mitigation of MP pollution. Recent advancements have focused on innovative methods such as membrane bioreactors, synthetic biology, organosilane-based techniques, biofilm-mediated remediation, and nanomaterial-enabled strategies. Nano-enabled technologies show substantial potential to enhance microplastic removal efficiency. Further investigation is necessary to develop advanced treatment technologies that can enhance the removal efficiency of microplastics (MPs) in drinking water. Additionally, more research is needed to understand the toxic impacts of MPs on marine ecosystems, including coral reefs, seagrass beds, mangroves, and other important habitats.

Biodegradation characterization and mechanism of low-density polyethylene by the enriched mixed-culture from plastic-contaminated soil

Plastic pollution poses significant ecological and health risks. In this study, we enriched microbial consortia from plastic-contaminated soil capable of degrading low-density polyethylene (LDPE) film over a 28-day incubation period. Using two kinds of enriched cultures, the mean film weight loss rate (WLR) of 0.27 ± 0.04 % (p < 0.01) was 9 times higher than the control. Scanning electron microscopy (SEM) revealed a average hole occurrence area of 0.67 ± 0.11 μm2 in the topmost sample, while the control had no change. Fourier transform infrared (FTIR) revealed specific changes in hydrophilicity (increased by 5.70 ± 0.02 times) and crystallinity (decreased by 15.73 ± 3.26 %). Meanwhile, FTIR analyses including peak occurrence at 3741 cm-1, carbonyl index and Lambert-Beer law calculations revealed moisture infiltration and predominant aldehyde carbonyl formation (88.69 % in total carbonyl). The results of high-throughput sequencing indicated Brevibacillus, Bacillus and Sporosarcina were dominate genera in the mixed-cultures, and PICRUSt2 implied they could use LDPE as the sole carbon source. Our study aims to provided theoretical basis driving plastic degradation and to mitigate plastic pollution based on microbial resource development.

Biodegradation of polyethylene with polyethylene-group-degrading enzyme delivered by the engineered Bacillus velezensis

Microplastics (MPs) pose an emerging threat to vegetable growing soils in Harbin, which have a relatively high abundance (11,065 n/kg) with 17.26 of potential ecological risk of single polymer hazard (EI) and 33.92 of potential ecological risk index (PERI). Polyethylene (PE) is the main type of microplastic pollution in vegetable growing soils in Harbin. In this study, the engineered Bacillus velezensis with polyethylene-group-degrading enzyme pathway (BCAv-PEase) was constructed to enhance the degradation of MPs of PE (PE-MPs). BCAv-PEase increased the biodegradation of PE-MPs, promoted weight loss of PE films, elevated surface tension, and decreased the surface hydrophobicity of PE through upregulating activities of depolymerases, dehydrogenase, and catalase. Mechanism analysis showed that BCAv-PEase degraded PE-MPs by promoting the secretion of PEase, thereby leading to the generation of new oxygenated functional groups within the PE-MPs substrate, which further accelerated the metabolic pathway of PE-MPs. The analysis of the microbial community during the PE-MPs degradation processes revealed that BCAv-PEase emerged as the principal bacterial player and stimulated the abundance of microbes and functional genes associated with the biodegradation of PE. In conclusion, this study provides a potential mechanism for biodegradation of PE-MPs mediated by BCAv-PEase via modulating substrate selectivity and optimizing biocatalytic pathways.

A novel Gordonia sp. PS3 isolated from the gut of Galleria mellonella larvae: Mechanism of polystyrene biodegradation and environmental toxicological evaluation

Plastic pollution is a global concern, with polystyrene (PS) being a major source of plastic waste. In this study, a PS-degrading bacterial strain, Gordonia sp. PS3, was isolated from the gut of Galleria mellonella larvae. After 40 days, strain PS3 exhibited a 33.59 ± 1.12 % degradation rate of PS-microplastics (PS-MPs). The biodegradation mechanism of PS by strain PS3 was investigated using genomics, molecular docking, and metabolomics. Degradation resulted in a significant decrease in molecular weight, disappearance of characteristic aromatic peaks, and the appearance of new functional groups (e.g., hydroxyl and carbonyl), indicating oxidative depolymerization and enhanced hydrophilicity. Four key enzymes involved in PS degradation were identified, with alkane 1-monooxygenase initiating cleavage of C-C bonds in PS and cytochrome P450 monooxygenase catalyzing oxidation of the aromatic ring. Metabolomics analysis revealed upregulation of proline, branched-chain amino acids, and polyamines, indicating oxidative stress response and energy acquisition during PS degradation. The PS degradation products showed no significant adverse effects on Arabidopsis thaliana growth, and PS residues were less harmful to G. mellonella larvae than untreated PS-MPs. This study presents a novel strain for PS biodegradation and provides new insights into the microbial degradation mechanism of PS and the safety of its degradation products.

Biofilm colonization on non-degradable and degradable microplastics change the adsorption of Cu(II) and facilitate the dominance of pathogenic microbes

Microplastics (MPs) have become a global concern as they can accumulate pollutants in aquatic environments. In this research, Cu(II) and non-degradable (polyamide, PA), degradable (polylactic acid, PLA) MPs were employed to reveal the potential connection among different aged MPs and heavy metal pollutants. The aging processes of MPs induced alterations in the surface morphologies, led to an augmentation of the specific surface area, and formed more biofilm and oxygen-containing groups on the MPs surface. The Qe of PA and PLA MPs increased from 0.102 to 0.989 to 1.192 and 2.457 mg/g after aging, respectively. The analysis of site energy distribution further verified that the enhanced adsorption capacity resulted from more high-energy adsorption sites obtained during the aging processes of MPs. Moreover, pathogenic bacteria and resistant bacteria were accumulated on the surface of MPs regardless of the aging environment, and the abundance and diversity of pathogenic bacteria on the biofilm of the PA surface were greater than those on the PLA MPs. This research offers an insight into the mechanism underlying microbial colonization and adsorption in the relationship between MPs and Cu(II), which is beneficial for judging the enrichment of heavy metals on MPs within the aquatic environment.

Insights Into the Efficiency and Health Impacts of Emerging Microplastic Bioremediation Approaches

The pollution caused by microplastics (MPs) is a global environmental and health concern. These plastic particles disrupt food chains and pose health risks to organisms, including humans. From a total of 827 studies, synthetic textiles (35%) and tires (28%) are the primary sources of MPs, with fibers being the most common shape (60%). MPs were detected in feces (44% of studies), lungs (35%), and blood (17%), indicating widespread contamination and potential health impacts. Bioremediation is a promising and sustainable method for mitigating MP pollution, as it uses microorganisms and plants to break down or convert MPs into less hazardous substances. However, it is important to understand and address the potential unintended consequences of bioremediation methods on the environment and human health. This scoping literature review examines the efficiency of currently emerging approaches for microplastic bioremediation, their strengths and weaknesses, and their potential impacts on the environment and human health. Highly effective methods such as mycoremediation, soil microbes for enhanced biodegradation, and phytoextraction were identified, but they pose high toxicity risks. Moderately effective methods include plant-assisted remediation, rhizosphere degradation, phytodegradation, and biodegradation, with effectiveness rates between 50% and 65% and moderate toxicity risks.

Tiny pollutants, big consequences: investigating the influence of nano- and microplastics on soil properties and plant health with mitigation strategies

The impact of nanoplastics (NPs) and microplastics (MPs) on ecosystems and human health has recently emerged as a significant challenge within the United Nations Agenda 2030, drawing global attention. This paper provides a critical analysis of the influence of plastic particles on plants and soils, with the majority of data collected from recent studies, primarily over the past five years. The absorption and translocation mechanisms of NPs/MPs in plants are first described, followed by an explanation of their effects-especially particles like PE, PS, PVC, PLA, and PES, as well as those contaminated with heavy metals-on plant growth, physiology, germination, oxidative stress, and nutrient uptake. The study also links the characteristics of plastics (size, shape, concentration, type, degradability) to changes in the physical, chemical, and microbial properties of soils. Various mitigation strategies, including physical, chemical, and biological processes, are explored to understand how they address these changes. However, further research, including both laboratory and field investigations, is urgently needed to address knowledge gaps, particularly regarding the long-term effects of MPs, their underlying mechanisms, ecotoxicological impacts, and the complex interactions between MPs and soil properties. This research is crucial for advancing sustainability from various perspectives and should contribute significantly toward achieving sustainable development goals (SDGs).

Dynamic impact of polyethylene terephthalate nanoplastics on antibiotic resistance and microplastics degradation genes in the rhizosphere of Oryza sativa L

This study examined the effects of polyethylene terephthalate (PET) nanoplastics on the rhizosphere of Oryza sativa L., focusing on dynamic changes and interactions among microbial communities, antibiotic resistance genes (ARGs) and microplastic degradation genes (MDGs). PET exposure altered the structure and function of soil microbial, enabling specific microbial groups to thrive in polluted environments. High-dose PET treatments markedly increased the abundance and dissemination of ARGs, primarily via resistance mechanisms such as antibiotic efflux and target alteration. By providing additional carbon sources and surfaces for microbial attachment, PET stimulated the growth of microorganisms harboring MDGs, resulting in an increase in MDGs abundance. The elevated expression of MDGs facilitated the propagation of ARGs, with overlapping host microorganisms suggesting that certain microbial groups exhibit dual metabolic capabilities, enabling them to endure both antibiotic and microplastic pressures. Toxic byproducts of microplastic degradation, such as mono-ethylhexyl phthalate, further promoted ARGs dissemination by increasing horizontal gene transfer frequency. Structural equation modeling revealed that PET indirectly influenced ARGs and MDGs expression by altering soil C/N ratio, available phosphorus, and enzyme activities. Thus, nanoscale PET exacerbates ecological risks to soil microbial communities by driving co-propagation of ARGs and MDGs, highlighting the persistent threat of composite pollution to agroecosystems.

From bulk to bits: understanding the degradation dynamics from plastics to microplastics, geographical influences and analytical approaches

The popularity of plastics in major application sectors is creating an increasing burden of pollutants in the environment in the forms of plastics and microplastics. More than 6 billion tons of plastics now reside in the environment, which is now an available source of secondary microplastics. Research focused on the degradation of plastics/microplastics dealing with different environmental conditions and their change in properties. Despite being a serious pollutant, sufficient resources are still missing for the transformation of secondary microplastics from large plastics and how to detect the level of degradation before this transition. This article's brief review provides insight into the current scenario of plastics, disposed waste plastics, management system, and their limitations. In addition, a detailed explanation of the transition of plastics to microplastics, their mechanism, and the effect of different geographical conditions on degradation is also demonstrated. Moreover, the available analytical techniques to understand the degradation index of different polymers are also described in addition to the future perspectives for research in this area. This review could provide valuable insight into the formation of microplastics from waste plastics and their mechanisms in addition to a comprehensive knowledge of the quantification of the degradation.

Biofilm-mediated bioremediation of xenobiotics and heavy metals: a comprehensive review of microbial ecology, molecular mechanisms, and emerging biotechnological applications

Environmental pollution, driven by rapid industrialization and urbanization, has emerged as a critical global challenge in the twenty-first century. This comprehensive review explores the potential of bacterial biofilms in bioremediation, focusing on their ability to degrade and transform a wide array of pollutants, including heavy metals, persistent organic pollutants (POPs), oil spills, pesticides, and emerging contaminants, such as pharmaceuticals and microplastics. The unique structural and functional characteristics of biofilms, including their extracellular polymeric substance (EPS) matrix, enhanced genetic exchange, and metabolic cooperation, contribute to their superior pollutant degradation capabilities compared to planktonic bacteria. Recent advancements in biofilm-mediated bioremediation include the application of genetically engineered microorganisms, nanoparticle-biofilm interactions, and innovative biofilm reactor designs. The CRISPR-Cas9 system has shown promise in enhancing the degradative capabilities of biofilm-forming bacteria while integrating nanoparticles with bacterial biofilms demonstrates significant improvements in pollutant degradation efficiency. As global pollution rises, biofilm-based bioremediation emerges as a cost-effective and environmentally friendly approach to address diverse contaminants. This review signifies the need for further research to optimize these techniques and harness their full potential in addressing pressing environmental challenges.

Microplastic Passage through the Fish and Crayfish Digestive Tract Alters Particle Surface Properties

Most studies on the effects of organisms on microplastic characteristics have focused on microorganisms, while the impact of animal feeding behavior, particularly in aquatic species like fish and decapod crustaceans, has been less explored. This study examines how polyethylene spherical microplastics (275 μm in diameter) passing through the digestive tracts of crucian carp (Carassius carassius) and Australian crayfish (Cherax quadricarinatus) affect surface properties, particle size, and bacterial colonization. The species were fed diets with or without microplastics. The particles underwent two rounds of passage through the digestive tracts and were then exposed to known bacterial densities. Surface damage, size, and biofilm coverage were analyzed using scanning electron microscopy, while alterations in surface chemical composition were assessed through Fourier transform infrared spectroscopy with attenuated total reflectance, and the formation and penetration of nanoplastics in gut tissues and glands were determined using Py-GC/MS. Results show that the passage significantly altered surface properties and reduced microplastic size, without affecting chemical composition or nanoplastic penetration into tissues. These changes promoted bacterial colonization compared to controls. The findings suggest that animal feeding activity may play an important role in the mechanical fragmentation of microplastics in aquatic environments, potentially leading to their faster degradation.

New insights into microbial degradation of polyethylene microplastic and potential polyethylene-degrading bacteria in sediments of the Pearl River Estuary, South China

Microplastics (MPs) are widely distributed pollutants in various ecosystems, and biodegradation is a crucial process for removal of MPs from environments. Pearl River Estuary, one of the largest estuaries in China, is an important reservoir for MPs with polyethylene MPs (PE-MPs) as the most abundant MPs. Here, biodegradation of PE-MPs and the potential PE-degrading bacteria in sediments of eight major outlets of Pearl River Estuary were firstly investigated. Results showed that biodegradation extent of PE-MPs varied for different sourced sediments, with highest extent for Hongqimen sediment and lowest extent for Jitimen sediment. Selective enrichment of specific bacteria occurred on PE-MPs with Pseudomonadaceae as the predominant family. Potential PE-degrading bacteria of Pseudomonas, Vulcaniibacterium, Cupriavidus, Bacillus were selectively enriched on PE-MPs and their abundance showed positive correlations with degradation extent of PE-MPs, indicating a vital role of them in degrading PE-MPs. Diverse pure cultured strains affiliated to the genera Bacillus, Pseudomonas, Priestia, Lysinibacillus, Marinobacter, Stutzerimonas and Achromobacter isolated from the plastispheres were capable of degrading PE-MPs rapidly, and members in Bacillus showed highest efffeciency of PE-MPs degradation with 6.5 % weight loss of PE-MPs within 40 days. This study provides a new perspective on the natural degradation potential by microbial communities in sediments.

The wheel of time: The environmental dance of aged micro- and nanoplastics and their biological resonance

The aging of micro- and nanoplastics (MNPs) significantly affects their environmental behavior and ecological impacts in both aquatic and terrestrial ecosystems. This review explored the known effects of aging on MNPs and identified several key perspectives. Firstly, aging can alter the environmental fate and transport of MNPs due to changes in their surface properties. This alteration accelerates their accumulation in specific habitats like oceans and soils, resulting in increased bioaccumulation by organisms. In addition, aged MNPs interact differently with living organisms than their pristine counterparts by influencing the attachment of biofilms and other microorganisms in aquatic ecosystems. Moreover, the aging processes of MNPs exhibit adverse effects on aquatic and terrestrial organisms via increasing the bioavailability and potential toxicity of MNPs as degradation products are released. Last but not least, the biodegradation potential of MNPs can be altered by the aging process, thus affecting their degradation rates and pathways in the environment. However, there are still knowledge gaps regarding the natural aging behaviors of MNPs, such as the aging mechanisms of different types of plastic, the influence of environmental factors, the release of pollutants, and even the effects of aging on their transformation in different ecosystems. Therefore, a great contribution can be made to sustainable plastic use and environmental preservation by studying the natural aging of common MNPs and their subsequent biological effects.

Microplastic interactions with co-existing pollutants in water environments: Synergistic or antagonistic roles on their removal through current remediation technologies

Composite water pollution, caused by microplastics (MPs) and co-occurring pollutants, is an emerging issue that induces synergistic toxicity. Multidimensional interactions occur between MPs and co-existing pollutants in a composite system, which alter the behavior of each component, resulting in unpredictable effects on the treatment processes. However, significant gaps exist in current review papers regarding MP‒pollutant interaction mechanisms and the corresponding synergistic or antagonistic effects on their removal processes. This review comprehensively describes the latest research in composite water pollution caused by MPs and various other pollutants with different compositions and states, systematically discusses their interaction mechanisms, and critically evaluates the impact of co-existing contaminants on the treatment performance of current remediation technologies. Based on current research progress and gaps, opportunities, challenges, and perspectives for future research directions are proposed. This review highlights state-of-the-art research related to composite water pollution caused by MPs and various pollutants, which is expected to inspire new strategies for the effective removal of multiple contaminants from the aquatic environment.

Interactions between nanoplastics and Tetrahymena thermophila: Low toxicity vs. potential biodegradation

Nanoplastics (NPs) are prevalent throughout the environment and have raised growing environmental concerns. Although numerous studies have examined the toxicological aspects of NPs, few have investigated their environmental fate and behavior when affected by organisms other than bacteria or fungi. Planktonic ciliates are essential components of aquatic ecosystems and play important roles in decomposing organic matter and transferring energy from the microbial food web to higher trophic levels. To investigate the interplay between NPs and the ciliate Tetrahymena thermophila, we executed a sequence of feeding experiments utilizing 50 nm polystyrene nanoplastics (PS-NPs). In the presence of sufficient nutrition, exposure to PS-NPs (even at concentrations up to 500 mg/L) did not significantly inhibit growth in Tetrahymena thermophila, indicating only a mild toxic effect of PS-NPs. When ingested by T. thermophila, the PS-NPs are repackaged into aggregates with lysosomal components in the food vacuole and finally expelled as compacted "fecal pellets". This process modifies the physical attributes of PS-NPs, including their hydrophilicity, aggregability, and buoyancy, influencing their transportation, retention, deposition dynamics, and ultimately their bioavailability within the environment. A total of 73 proteins were identified from the fecal pellets, containing various hydrolases. Gel permeation chromatography (GPC), Fourier transform infrared (FTIR), and thermogravimetric analysis (TGA) were used to identify changes in molecular weights, functional groups, and thermal stabilities of PS-NP residues in fecal pellets. The results verified the degradation of PS-NPs during the passage through the T. thermophila cell.

Bacillus subtilis, a promising bacterial candidate for trapping nanoplastics during water treatment

As a probiotic, Bacillus subtilis (B. subtilis) has a wide range of application values. In this study, the trap by B. subtilis and the effect of NPs on its growth physiology were studied. Confocal laser scanning microscopy (LCSM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that PS-NPs were trapped by B. subtilis when they were exposed to PS-NPs. At this point, most of the PS-NPs are clustered around B. subtilis. Flow cytometry showed that at 10 mg/L, 73.7 % of PS-NPs' environmental state changed. The complexity of 9.73 %, 23.77 %, 43.27 %, and 65.13 % of B. subtilis increased at PS-NP concentrations of 10, 20, 50, and 200 mg/L, respectively. The increase in overall EPS secretion ranged from 0.51 ∼ 7.13 μg/mL after adding different concentrations of PS-NPs. The effect of different concentrations of PS-NPs on NAR activity ranged from -11.38 ∼ 16.2 %, on NIR activity from -17.90 ∼ 7.22 %, on NOR activity from -15.10 ∼ 7.69 % and on NO2R activity from -14.01 ∼ 17.03 %. These results indicated that B. subtilis can process nitrogen compounds in water while capturing NPs in the environment. They have the potential to be candidate bacteria in the water treatment process, and specific applications are needed to research further.

Pulse exposure to microplastics depolarizes the goldfish gill: Interactive effects of DOC and differential degradation

Microplastics (MPs) are constantly degrading while moving through aquatic systems as a result of mechanical abrasion, thermal fluctuations, UV light, and chemical exposure. As such, fish may experience pulse exposures to differentially degraded plastics. This study addresses how pulse exposures, over the course of minutes, to differentially degraded microplastics alters a key ionoregulatory property of the goldfish gill. We used transepithelial potential (TEP) across the gills, a diffusion potential resulting from the differential permeability of cations versus anions, as a sensitive indicator of potential ionoregulatory effects. Virgin (non-degraded) MPs along with mechanically, UV, and thermally degraded plastics immediately depolarized the gills (less negative TEP), whereas chemically degraded MPs resulted in no change to TEP. To further explore the physicochemical interaction between the surface of the gill and MPs, combinations of MPs and a single source of dissolved organic carbon (DOC) were tested and revealed that the presence of DOC negated the effects of MPs at the gill regardless of whether DOC or MPs were introduced first. This study suggests that while MPs have the ability to cause ionoregulatory effects at the gill, the effects of ambient water quality, specifically the presence of DOC, are of greater influence.

The microplastic-crisis: Role of bacteria in fighting microplastic-effects in the digestive system

Plastic particles smaller than 5 mm, referred to as Microplastics, pose health risks, like metabolic, immunological, neurological, reproductive, and carcinogenic effects, after being ingested. Smaller plastic particles are more likely to be absorbed by human cells, with nanoplastics showing higher potential for cellular damage, including DNA fragmentation and altered protein functions. Micro- and nanoplastics (MNPs) affect the gastrointestinal tract by altering the microbial composition, they could influence digestive enzymes, and possibly disrupt mucus layers. In the stomach, they potentially interfere with digestion and barrier functions, while in the intestines, they could increase permeability via inflammation and tissue disruption. MNPs can lead to microbial dysbiosis, leading to gastrointestinal symptoms. By activating inflammatory pathways, altering T cell functions and affecting dendritic cells and macrophages, immune system homeostasis could possibly be disrupted. Probiotics offer potential strategies to alleviate plastic effects, by either degrading plastic particles or directly countering health effects. We compared genetic sequences of probiotics to the genome of known plastic degraders and concluded that no probiotic bacteria could serve the role of plastic degradation. However, probiotics could directly mitigate MNP-health effects. They can restore microbial diversity, enhance the gut barrier, regulate bile acid metabolism, reduce inflammation, regulate insulin balance, and counteract metabolic disruptions. Antioxidative properties protect against lipid peroxidation and MNP-related reproductive system damage. Probiotics can also bind and degrade toxins, like heavy metals and bisphenol A. Additionally, bacteria could be used to aggregate MNPs and reduce their impact. Therefore, probiotics offer a variety of strategies to counter MNP-induced health effects.

Microbial Biodegradation of Synthetic Polyethylene and Polyurethane Polymers by Pedospheric Microbes: Towards Sustainable Environmental Management

This study attempted to isolate and identify pedospheric microbes originating in dumpsites and utilized them for the degradation of selected synthetic polymers for the first time in a cost-effective, ecologically favorable and sustainable manner. Specifically, low-density polyethylene (LDPE) and polyurethane (PUR) were converted by the isolated fungi, i.e., Aspergillus flavus, A terreus, A. clavatus, A. nigers and bacterial coccus and filamentous microbes and assessed in a biotransformative assay under simulated conditions. Commendable biodegradative potentials were exhibited by the isolated microbes against polymers that were analyzed over a span of 30 days. Among the selected fungal microbes, the highest activity was achieved by A. niger, expressing 55% and 40% conversion of LDPE and PUR, respectively. In the case of bacterial strains, 50% and 40% conversion of LDPE and PUR degradation was achieved by coccus. Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) were utilized to analyze the degradative patterns in terms of vibrational and thermal characteristics, and stereomicroscopic analysis was performed for the visual assessment of morphological variations. Profound structural transformations were detected in FT-IR spectra and TGA thermograms for the selected microbes. Stereomicroscopic analysis was also indicative of the remarkable transformation of the surface morphology of these polymers after degradation by microbes in comparison to the reference samples not treated with any pedospheric microbes. The results are supportive of the utilization of the selected pedospheric microbes as environmental remediators for the cleanup of persistent polymeric toxins. This current work can be further extended for the successful optimization of further augmented percentages by using other pedospheric microbes for the successful adoption of these biotechnological tools at a practical level.

Exploring the intricate studies on low-density polyethylene (LDPE) biodegradation by Bacillus cereus AP-01, isolated from the gut of Styrofoam-fed Tenebrio molitor larvae

This study aims to investigate the biodegradation potential of a gut bacterial strain, Bacillus cereus AP-01, isolated from Tenebrio molitor larvae fed Styrofoam, focusing on its efficacy in degrading low-density polyethylene (LDPE). The biodegradation process was evaluated through a series of assays, including clear zone assays, biodegradation assays, and planktonic cell growth assessments in mineral salt medium (MSM) over a 28-day incubation period. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were employed to characterize the alterations in LDPE pellets, followed by molecular characterization. Over three months, sterile soil + LDPE pellets were treated with different concentrations of gut bacterial strain. The degradation capabilities were assessed by measuring pH, total microbial counts, carbon dioxide evolution, weight loss, and conducting phase contrast microscopy and mechanical strength tests. Results demonstrated that MSM containing LDPE as a carbon source with gut bacterial strain produced a clear zone and enhanced planktonic cell growth. FTIR analysis revealed the formation of new functional groups in the LDPE, while SEM images displayed surface erosion and cracking, providing visual evidence of biodegradation. Molecular characterization confirmed the strain as Bacillus cereus AP-01 (NCBI Accession Number: OR288218.1). A 10% inoculum concentration of Bacillus cereus AP-01 exhibited increased soil bacterial counts, carbon dioxide evolution, and pH levels, alongside a notable weight loss of 30.3% in LDPE pellets. Mechanical strength assessments indicated substantial reductions in tensile strength (7.81 ± 0.84 MPa), compression (4.92 ± 0.53 MPa), hardness (51.96 ± 5.62 shore D), flexibility (10.62 ± 1.15 MPa), and impact resistance (14.79 ± 0.94 J). These findings underscore the biodegradation potential of Bacillus cereus AP-01, presenting a promising strategy for addressing the global LDPE pollution crisis.

Microplastics regulate soil microbial activities: Evidence from catalase, dehydrogenase, and fluorescein diacetate hydrolase

Soil microbiomes drive many soil processes and maintain the ecological functions of terrestrial ecosystems. Microplastics (MPs, size <5 mm) are pervasive emerging contaminants worldwide. However, how MPs affect soil microbial activity has not been well elucidated. This review article first highlights the effects of MPs on overall soil microbial activities represented by three soil enzymes, i.e., catalase, dehydrogenase, and fluorescein diacetate hydrolase (FDAse), and explores the underlying mechanisms and influencing factors. Abundant evidence confirms that MPs can change soil microbial activities. However, existing results vary greatly from inhibition to promotion and non-significance, depending on polymer type, degradability, dose, size, shape, additive, and aging degree of the target MPs, soil physicochemical and biological properties, and exposure conditions, such as exposure time, temperature, and agricultural practices (e.g., planting, fertilization, soil amendment, and pesticide application). MPs can directly affect microbial activities by acting as carbon sources, releasing additives and pollutants, and shaping microbial communities via plastisphere effects. Smaller MPs (e.g., nanoplastics, 1 to <1000 nm) can also damage microbial cells through penetration. Indirectly, MPs can change soil attributes, fertility, the toxicity of co-existing pollutants, and the performance of soil fauna and plants, thus regulating soil microbiomes and their activities. In conclusion, MPs can regulate soil microbial activities and consequently pose cascading consequences for ecosystem functioning.

Rhizospheric bacterial communities against microplastics (MPs): Novel ecological strategies based on the niche differentiation

Considerable amounts of microplastics (MPs) are stocked in plant rhizospheres, yielding adverse effects on rhizospheric microorganisms and threatening plant health. However, the adaptation of the rhizospheric microbiota for MPs remains largely unknown. Here, to evaluate the adaptive strategies of rhizospheric bacterial communities against MPs, we characterized the spatial dissimilarities in MPs properties and bacterial communities from mangrove non-rhizosphere to rhizosphere to root hair sediments. Consequently, two strategies were uncovered: (1) Bacterial communities showed significant niche differentiation induced by the increasingly enriched MPs evaluated by piecewise structural equation modeling (piecewise SEM), as increasing specialization (10.2 % to 19.4 % to 23.0 % of specialists) and decreasing generalization (10.4 % to 10.2 % to 8.7 % of generalists). (2) A self-remediation strategy of enhancing microbial plastic-degrading potentials was determined in bacterial communities, tightly coupled to the increase of specialists (linear regression analysis, R2 = 0.54, P < 0.001) and increasing MPs weathering degrees visualized by the scanning electron microscopy (SEM) from non-rhizosphere to rhizosphere to root hair regions. Our study provides a novel insight into the ecological strategies that rhizospheric microbes utilize against MPs, and broadens our knowledge of the interaction between soil microbes and global MPs pollution.

The effect of polyvinyl chloride microplastics on soil properties, greenhouse gas emission, and element cycling-related genes: Roles of soil bacterial communities and correlation analysis

Different shapes (membranes and particles) and concentrations (1 % (w/w) and 2 % (w/w)) of polyvinyl chloride (PVC) microplastics (MPs) were investigated to determine their impact on the soil environment. The incorporation of MPs can disrupt soil macroaggregates. Compared with 1 % (w/w) MPs, 2 % MPs resulted in a significant increase in soil organic carbon content. MP particles significantly increased soil CO2 emissions, and CH4 emissions were enhanced by both membrane and particle MPs at high concentrations. Microplastics can alter the abundance of Actinobacteria, Proteobacteria, Chloroflexi, Acidobacteriota, and Firmicutes at the phylum level, and Nocardioides, Rhodococcus and Bacillus at the genus level. MP particles had a more significant impact on soil bacterial communities than MP membranes. The relative abundances of genes involved in the C, N, and P cycles were detected by qPCR, and more remarkable changes were observed in MP membrane treatments. The relative abundance of Vicinamibacteraceae and Vicinamibacterales exhibited a positive correlation with most C/N/P cycle-related genes, whereas Pseudarthrobacter and Nocardioides demonstrated a negative correlation. This study highlights that the influence of MPs on soil parameters is mediated by soil microorganisms, providing insight into the effects of MPs on the soil microenvironment.

Microbial degradation of polyethylene polymer: current paradigms, challenges, and future innovations

Polyethylene (PE) is the second most commonly used plastic worldwide, mainly used to produce single-use items such as bags and bottles. Its significant resistance to natural biodegradation results in the accumulation of PE in landfills, leading to various ecological and toxicological consequences. Despite extensive research on the microbial degradation of PE, achieving complete biodegradation remains a challenge. Comparing experimental outcomes is complicated by the diverse array of microbes involved in PE biodegradation, variations in culture conditions, and differences in assessment tools. This review discusses the critical hurdles in PE biodegradation experiments, including the chemical complexity of PE substrates and the challenges of isolating effective microbes and forming stable consortia. The review also delves into the difficulties in accurately assessing microbial metabolic activity and understanding the biochemical pathways involved in PE degradation. Furthermore, it addresses the pressing issues of metabolic byproducts, slow degradation rates, scalability concerns, and the challenges in measuring biodegradation levels effectively. In addition to outlining the technical challenges associated with PE experiments, this review offers recommendations for future research directions to enhance PE biodegradation outcomes. Overcoming these challenges and implementing the proposed future strategies will improve the reliability, comparability, and practicality of current PE biodegradation experiments, ultimately contributing to better comprehension and management of PE waste in the environment.

Individual and Combined Effects of Nanoplastics and Cadmium on the Rhizosphere Bacterial Community of Sedum alfredii Hance

Nanoplastics (NPs) and cadmium (Cd) coexist in soil, but the combined effects of NPs and Cd on the rhizosphere bacterial community remain unknown. In this study, high-throughput sequencing and PICRUSt2 functional analysis were employed to explore the individual and combined effects of polystyrene (PS) NPs (low concentration [N1, 100 mg·kg-1] and high concentration [N2, 1000 mg·kg-1]) and Cd (low concentration [C1, 0.6 mg·kg-1] and high concentration [C2, 4 mg·kg-1]) on the diversity, structural composition, and function of the rhizosphere bacterial community associated with Sedum alfredii Hance. Individually, PS NPs and Cd significantly reduced the soil pH, while the combined treatments induced a more significant decrease in pH. In contrast, combined PS NPs and Cd significantly increased the diethylenetriaminepentaacetic acid-Cd (DTPA-Cd) and total Cd concentrations. Compared with individual treatments, C2N2 significantly increased DPTA-Cd by 4.08%. N1 had no significant effect on the Chao1, observed species, or Shannon indices, while N2 significantly reduced the richness and diversity of the rhizosphere bacteria and altered their community structure. Furthermore, adding PS NPs exacerbated the effect of Cd on rhizosphere bacterial communities. Compared with individual Cd treatments, C2N2 significantly reduced the relative abundances of Actinobacteriota, Bacteroidota, Crenarchaeota, and Myxococcota by 19.76%, 2.01%, 1.49%, and 2.00%, respectively, and significantly increased the relative abundance of Acidobacteriota by 16.05%. A cluster heat map showed that the combined treatments attenuated glycan biosynthesis and metabolic function and enhanced the metabolism of cofactors and vitamins. These findings illuminate rhizosphere processes under co-contamination with heavy metals and PS NPs, supporting the practical application of phytoremediation to alleviate combined Cd and PS NP pollution.

Cutting-edge developments in plastic biodegradation and upcycling via engineering approaches

The increasing use of plastics has resulted in the production of high quantities of plastic waste that pose a serious risk to the environment. The upcycling of plastics into value-added products offers a potential solution for resolving the plastics environmental crisis. Recently, various microorganisms and their enzymes have been identified for their ability to degrade plastics effectively. Furthermore, many investigations have revealed the application of plastic monomers as carbon sources for bio-upcycling to generate valuable materials such as biosurfactants, bioplastics, and biochemicals. With the advancement in the fields of synthetic biology and metabolic engineering, the construction of high-performance microbes and enzymes for plastic removal and bio-upcycling can be achieved. Plastic valorization can be optimized by improving uptake and conversion efficiency, engineering transporters and enzymes, metabolic pathway reconstruction, and also using a chemo-biological hybrid approach. This review focuses on engineering approaches for enhancing plastic removal and the methods of depolymerization and upcycling processes of various microplastics. Additionally, the major challenges and future perspectives for facilitating the development of a sustainable circular plastic economy are highlighted.

Bacterial degradation of polyethylene and polypropylene microplastics in a mangrove ecosystem

Microplastics (MPs) contamination presents a major environmental challenge, with accumulation of thousands of tons of MPs in ecosystems worldwide posing significant risks to human health and biodiversity. Identifying bacteria capable of degrading MPs offers a promising long-term solution to this issue. While several bacterial strains have demonstrated varying degrees of plastic degradation, the mechanisms underlying these processes remain poorly understood. In this study, 16S rDNA analysis was used to screen ten bacterial strains isolated from mangrove water samples for their potential to degrade MPs. Among these, Bacillus cereus strain ZRY and Pseudochrobactrum saccharolyticum strain ZRY emerged as the most effective candidates. The degradation of polyethylene (PE) and polypropylene (PP) was monitored through weight loss measurements over a 60-day incubation period. B. cereus strain ZRY achieved weight losses of 1.1% for PE and 1.0% for PP, while P. saccharolyticum strain ZRY recorded losses of 0.6% for PE and 0.4% for PP. Morphological and structural changes during degradation were analyzed using scanning electron microscopy, Fourier transform infrared spectroscopy, and atomic force microscopy, which also identified key enzymes produced by both bacterial strains that facilitate the degradation of MPs. Additionally, the effect of pH, salt concentrations, inorganic ions, and incubation duration on degradation efficiency were evaluated. Our findings demonstrate the potential of these bacterial strains for MPs degradation, underscoring their potential for future applications in addressing MP pollution. This research lays the foundation for optimizing conditions to enhance bioremediation efforts utilizing these microbial candidates.

Characterization, surface deformation analysis and sources of small plastic fragments collected in diverse environments of Egypt

This study investigates the sources and morphological characteristics of plastic waste across diverse Egyptian environments-marine (Mediterranean and Red Seas), freshwater (River Nile), and terrestrial (urban streets). Predominant plastics found in various marine areas include polyethylene and polypropylene, originating from both maritime and urban sources. In the Mediterranean, these plastics show higher levels of UV-induced degradation, resulting in fragments measuring 18-22 mm in size and 1-1.2 mm in thickness. The River Nile exhibits polystyrene fragments, with average sizes of 20-26 mm and thicknesses of 0.7-0.9 mm influenced by urban and agricultural runoff. Urban streets display a mix (polypropylene, polyethylene, and polystyrene), with thicker fragments (averaging 1.8 mm) due to mechanical wear and pollution. Analysis shows varying surface loss: Mediterranean (29 %), Red Sea (20-23 %), freshwater (18 %), and urban streets (up to 30 %), indicate differential degradation influenced by environmental conditions and human activities. These findings underscore the need for targeted policies to mitigate plastic pollution across Egypt's landscapes, crucial for global conservation efforts.

Microplastics-biofilm interactions in biofilm-based wastewater treatment processes: A review

Microplastics, pervasive contaminants from plastic, present significant challenges to wastewater treatment processes. This review critically examines the interactions between microplastics and biofilm-based treatment technologies, specifically focusing on the concepts of "biofilm on microplastics" and "microplastics in biofilm". It discusses the implications of these interactions in contaminant removal and process performance. Advanced characterization techniques, including morphological characterization, chemical composition analysis, and bio-information analysis, are assessed to elucidate the complex interplay between microplastics and biofilms within biofilters, biological aerated filters (BAFs), rotating biological contactors (RBCs), and moving bed biofilm reactors (MBBRs). This review synthesizes current research findings, highlighting that microplastics can either hinder or enhance the treatment processes, contingent on their concentration, physicochemical properties, and the specific biofilm technology employed. The insights gained from this review are essential for developing strategies to mitigate the adverse effects of microplastics and for optimizing the design and operation of wastewater treatment.

Can Mammalian Reproductive Health Withstand Massive Exposure to Polystyrene Micro- and Nanoplastic Derivatives? A Systematic Review

The widespread use of plastics has increased environmental pollution by micro- and nanoplastics (MNPs), especially polystyrene micro- and nanoplastics (PS-MNPs). These particles are persistent, bioaccumulative, and linked to endocrine-disrupting toxicity, posing risks to reproductive health. This review examines the effects of PS-MNPs on mammalian reproductive systems, focusing on oxidative stress, inflammation, and hormonal imbalances. A comprehensive search in the Web of Science Core Collection, following PRISMA 2020 guidelines, identified studies on the impact of PS-MNPs on mammalian fertility, including oogenesis, spermatogenesis, and folliculogenesis. An analysis of 194 publications revealed significant reproductive harm, such as reduced ovarian size, depleted follicular reserves, increased apoptosis in somatic cells, and disrupted estrous cycles in females, along with impaired sperm quality and hormonal imbalances in males. These effects were linked to endocrine disruption, oxidative stress, and inflammation, leading to cellular and molecular damage. Further research is urgently needed to understand PS-MNPs toxicity mechanisms, develop interventions, and assess long-term reproductive health impacts across generations, highlighting the need to address these challenges given the growing environmental exposure.

Metagenomics analysis yields assembled genomes from prokaryotic anaerobes with polymer-degrading potential

Anaerobic microbial communities are often highly degradative, such as those found in the herbivore rumen and large-scale anaerobic digesters. Since the microbial communities in these systems degrade recalcitrant organic polymers, we hypothesize that some microbes in anaerobic environments may be involved in man-made plastic association, deformation, or even breakdown. While efforts have been put toward characterizing microbial communities, many microbes remain unidentified until they can be sufficiently cultivated to generate enough genetic material to assemble high-quality metagenome assemblies and reference genomes. In this study, microbial consortia from goat fecal pellets and anaerobic digester sludge were cultivated for over 6 weeks to assemble metagenomes from novel anaerobic taxa with potential degradative activity. To select for microbes with potential plastic-degrading abilities, plastic strips were included in culture, though the presence of plastic did not appear to enrich for particularly degradative consortia, yet it did select for novel species that otherwise may not have been characterized. Whole-genome shotgun sequencing enabled assembly of 72 prokaryotic metagenome-assembled genomes (MAGs) with >90% completion, <5% contamination, and an N50 >10,000 bp; 17 of these MAGs are classified as novel species given their lack of similarity to publicly available genomes and MAGs. These 72 MAGs vary in predicted carbohydrate-degrading abilities, with genes predicted to encode fewer than 10 or up to nearly 400 carbohydrate-active enzymes. Overall, this enrichment strategy enables characterization of less abundant MAGs in a community, and the MAGs identified here can be further mined to advance understanding of degradative anaerobic microbial consortia.

Beach wracks microbiome and its putative function in plastic polluted Mediterranean marine ecosystem

The coasts of the world's oceans and seas accumulate various types of floating debris, commonly known as beach wracks, including organic seaweeds, seagrass, and ubiquitous anthropogenic waste, mainly plastic. Beach wrack microbiome (MB), surviving in the form of a biofilm, ensures decomposition and remineralization of wracks, but can also serve as a vector of potential pathogens in the environment. Through the interdisciplinary approach and comprehensive sampling design that includes geological analysis of the sediment, plastic debris composition analysis (ATR-FTIR) and application of 16S rRNA gene metabarcoding of beach wrack MBs, this study aims to describe MB in relation to beach exposure, sediment type and plastic pollution. Major contributors in beach wrack MB were Proteobacteria, Bacteroidetes, Actinobacteria, Planctomycetes, Verrucomicrobia and Firmicutes and there was significant dissimilarity between sample groups with Vibrio, Cobetia and Planococcus shaping the Exposed beach sample group and Cyclobacteriaceae and Flavobacterium shaping the Sheltered beach sample group. Our results suggest plastisphere MB is mostly shaped by beach exposure, type of seagrass, sediment type and probably beach naturalness with heavy influence of seawater MB and shows no significant dissimilarity between MBs from a variety of microplastics (MP). Putative functional analysis of MB detected plastic degradation and potential human pathogen bacteria in both beach wrack and seawater MB. The research provides the next crucial step in beach wrack MP accumulation research, MB composition and functional investigation with focus on beach exposure as an important variable.

Microplastics-biofilm in aquatic ecosystem: Formation, pollutants complexation, greenhouse gas emission and ecotoxicology

The omnipresent microplastics (MPs) have gradually become a significant environmental problem due to its adverse consequences for ecological systems. MPs serve as substrates for biofilms colonization, which enhances adsorption of harmful contaminants on MPs surface in the aquatic ecosystem. The present study provides a critical discussion on the mechanism involved in MPs-biofilm formation, microbial colonization and the robust factors influencing the process in the aquatic ecosystem. Subsequently, the impact of MPs-biofilm on adsorption of inorganic and organic contaminants is explored. The ecological significance of MPs-biofilm associated pollutant complex for promoting greenhouse gases (GHGs) emissions from aquatic ecosystem is extensively discussed for understanding the climatic risk. Furthermore, the discussion is extended over ecotoxicological impact of MPs-biofilm on aquatic biodiversity and humans. The protective extracellular polymeric substances secreted by colonised bacteria over MPs during biofilm formation creates sticky MPs surface for heteroaggregates formation with swift adsorption of chemical compounds and microorganisms. MPs with functional aromatic groups facilitate the bacterial adhesion on the surface, but affect formation of biofilm. Alternatively, MPs-biofilm promotes the Mn and Fe hydrous oxides formation that can co-precipitate with heavy metal ions and facilitate in remediation measures. However, MPs biodegradation generates GHGs emission per unit mass, comparably more from freshwater than marine ecosystem. Considering the toxicity, MPs-biofilm induces the oxidative response in fishes, causing painful death and thus, destroys aquatic biodiversity. This study will be useful to address MPs-biofilm associated pollution scenario via trace, test and treat strategy involving future engineering research framework for ecological restoration.

Microplastics and silver nanoparticles compromise detrital food chains in streams through effects on microbial decomposers and invertebrate detritivores

Abundance of microplastics (MPs) in freshwater ecosystems has become an emerging concern due to their persistence, toxicity and potential interactions with other contaminants. Silver nanoparticles (Ag-NPs), which share common sources with MPs (e.g., personal care products), are also a subject of concern. Thus, the high probability of co-occurrence of both contaminants raises additional apprehensions. This study assessed, for the first time, the impacts of MPs and Ag-NPs, alone or in mixtures, on stream detritus food webs. Physiological and ecological responses of aquatic fungal communities, invertebrate shredders (Allogamus sp.) and collectors (Chironomus riparius) were examined. Additionally, antioxidant enzymatic responses of microbes and shredders were analyzed to unravel the mechanisms of toxicity; also, neuronal stress responses of Allogamus sp. were assessed based on the activities of cholinesterases. Organisms were exposed to environmentally realistic concentrations of polyethylene MPs, extracted from a personal care product (0.1, 0.5 and 10 mg L-1), for 7 days, in the absence or presence of Ag-NPs (0.1 mg L-1 and 1 mg L-1). The exposure to both contaminants reduced the growth rates of all tested organisms. MPs, Ag-NPs, and their mixtures led to a decrease in leaf litter decomposition by fungi and shredders. The availability of fine particulate organic matter, released by the shredders, increased when exposed to these contaminants. The negative effects of these contaminants were further strengthened by the responses of antioxidant enzymes that revealed high level of oxidative stress in both fungi and Allogamus sp. Moreover, the activities of cholinesterases showed that Allogamus sp. were under neuronal stress upon exposure to both contaminants. The impacts in mixtures were stronger than those of individual contaminants suggesting interactive effects. Overall, our study showed adverse effects of MPs and Ag-NPs across trophic levels and indicated that they may compromise key processes, such as organic matter decomposition in streams.

Impacts of microplastics on ecosystem services and their microbial degradation: a systematic review of the recent state of the art and future prospects

Microplastics are tiny plastic particles with a usual diameter ranging from ~ 1 μ to 5 µm. Recently, microplastic pollution has raised the attention of the worldwide environmental and human concerns. In human beings, digestive system illness, respiratory system disorders, sleep disturbances, obesity, diabetes, and even cancer have been reported after microplastic exposure either through food, air, or skin. Similarly, microplastics are also having negative impacts on the plant health, soil microorganisms, aquatic lives, and other animals. Policies and initiatives have already been in the pipeline to address this problem to deal with microplastic pollution. However, many obstacles are also being observed such as lack of knowledge, lack of research, and also absence of regulatory frameworks. This article has covered the distribution of microplastics in water, soil, food and air. Application of multimodel strategies including fewer plastic item consumption, developing low-cost novel technologies using microorganisms, biofilm, and genetic modified microorganisms has been used to reduce microplastics from the environment. Researchers, academician, policy-makers, and environmentalists should work jointly to cope up with microplastic contamination and their effect on the ecosystem as a whole which can be reduced in the coming years and also to make earth clean.

Determination of Biodegradation Potential of Aspergillus niger, Candida albicans, and Acremonium sclerotigenum on Polyethylene, Polyethylene Terephthalate, and Polystyrene Microplastics

Plastics are used widely in almost every field of life, but their synthetic and persistent nature makes them harmful for the environment. The aim of this research was to evaluate the degradation abilities of Aspergillus niger, Candida albicans, and Acremonium sclerotigenum on microplastics (MPs). MP pieces of 4 ± 1 mm, including polyethylene, polyethylene terephthalate, and polystyrene, were incubated with fungal inoculums for 30 days. The degradation of treated MPs was determined by biofilm formation, weight loss, scanning electron microscopy (SEM), and Fourier transform analyses. The results indicated that the polyethylene MPs treated with Aspergillus niger exhibited the highest level of biofilm formation (optical density 1.595) and percentage weight loss (16%). In the case of polyethylene terephthalate and polystyrene MPs, Acremonium sclerotigenum and co-culture showed weight loss of 6% and 10%, respectively. Candida albicans was observed to be the least effective in biodegradation analyses. SEM observation revealed the surface modifications as holes, pits, cracks, and increased roughness in treated MPs. Fourier transform infrared (FTIR) spectroscopy showed that the chemical structure of each polymer exhibited some variations. The study concluded that the fungal strains play an important role in the biodegradation of plastics and can be utilized to mitigate environmental pollution.

Impact of microplastics on strength parameters of clayey, Sandy, silty soil: A comparative assessment

The comparative assessment of a variety of microplastic contamination on various soil types hasn't been extensively explored in existing literature. The present study focuses on the comparative analysis of the impact of environmentally relevant concentrations of LDPE, HDPE, and PVC microplastic contamination (2 %, 4 %, and 6 %) on index properties and strength parameters of sandy, silty and clayey soil types at varying observation days 5,10,15,20,25, and 30 days. Extensive experimental investigations are carried out to understand the effect of contamination on moisture content, specific gravity, liquid limit, plastic limit, plasticity index, optimum moisture content, maximum dry density, and shear strength parameters of the respective soil type. It is observed that the depletion in Atterberg's limits is found more in the case of clayey soil as compared to silty soil because clayey soils consist of large specific surface areas leading to van der Waals force of attraction being the predominant force between particles, compared with silty soil which is affected by microplastic addition leading to decrease in net attractive forces. In the case of clayey soil maximum depletion of liquid limit up to 168 %, plastic limit up to 33 %, plasticity index (136 %), and optimum moisture content (9.04 %) is observed for PVC microplastic. The deduction in maximum dry density values is observed more for sandy soil (0.59 g/cc) followed by silty soil (0.21 g/cc) and clayey soil (0.12 g/cc). The maximum depletion of moisture content(delta-8 %), shear strength (delta-0.89 kg/cm2), and maximum dry density (delta-0.44 g/cc) is observed in the case of sandy soil for PVC and LDPE microplastic contamination. Significant depletion in optimum moisture content is observed in the case of clayey soil (9.57 %) compared to sandy (5.62 %) and silty soil (5.3 %). An increase in cohesion is observed for sandy soil (0.09 kg/cm2) and a decrease for clayey (0.19 kg/cm2) and silty soil (0.19 kg/cm2). The angle of internal friction is reduced in the case of clayey soil (∆-14.380) followed by silty soil (∆-11.230) and sandy soil (∆-11.020). For silty soil maximum depletion of specific gravity(delta-1.06) and cohesion (0.192 kg/cm2) is observed for LDPE and HDPE microplastic. The sandy soil type is most affected due to microplastic contamination irrespective of the type of microplastic contamination followed by clayey soil and the silty soil type is least affected. The maximum overall shear strength is reduced due to microplastic contamination in all the soil types.

Unravelling the influence of microplastics with/without additives on radish (Raphanus sativus) and microbiota in two agricultural soils differing in pH

Here we investigated the effects of three types of microplastics (MPs), i.e., PS (P), ABS (B), PVC (V), and each with additive (MPAs) (PA, BA, and VA), on soil health, microbial community, and plant growth in two acidic and slightly alkaline soils. Incubation experiment revealed that although MPs and MPAs consistently stimulated soil nutrients and heavy metals (e.g., Mn, Cu) in weakly alkaline soils, only BA and VA led to increase in soil nutrients and heavy metals in acidic soils. This suggests distinct response patterns in the two soils depending on their initial pH. Concerning microorganisms, MPs and MPAs reduced the assembly degree of bacteria in acidic soils, with a reduction of Chloroflexi and Acidobacteriota but an increase of WPS-2 in VA. Culture experiment showed consistent positive or negative responses in radish seed germination, roots, and antioxidant activity across MPs and MPAs types in both soils, while the responses of seed heavy metals (e.g., Cr, Cd) were consistent in acidic soils but dependent on MPs and MPAs types in alkaline soils. Therefore, our study strongly suggests that the effects of MPs on soil-microbial-plant systems were highly dependent on initial soil characteristics and the types of MPs with plastic additives.

Microplastics in wild fish in the Three Gorges Reservoir, China: A detailed investigation of their occurrence, characteristics, biomagnification and risk

Microplastics (MPs) pollution in freshwater poses a risk to various ecosystems and health security. In 2018, the Chinese government banned fishing since 2018 in the Three Gorges Reservoir (TGR), but the fate and risk of MPs in wild fish remain unclear. Therefore, a detailed investigation was conducted into the occurrence of MPs in 18 wild fish species in the TGR using a Micro Fourier Transform Infrared Spectrometer, and the trophic transfer and risks were assessed. MPs in fish were aged, with abundances ranging from 0.68 ± 0.98 to 4.00 ± 2.12 items/individual. Most particles were less than 1 mm in size (73.4 %), with fibers being the dominant shape (48.9 %) and transparent as the dominant color (35 %). Polyethylene (PE) was the most prevalent type. The bioconcentration factor (BCF), bioaccumulation factor (BAF), trophic magnification factor (TMF) and polymer hazard index (PHI) were low, suggesting no trophic transfer and a low risk of MPs. The BAF may provide a more reasonable description of the degree of enrichment of MPs, and 'items/individual' or 'g/individual' can be used to describe MPs concentrations in fish. This study proposes new insights and prospectives that can help researchers better understand MPs enrichment in fish across various trophic levels.

Isolation and Identification of Four Strains of Bacteria with Potential to Biodegrade Polyethylene and Polypropylene from Mangrove

With the rapid growth of global plastic production, the degradation of microplastics (MPs) has received widespread attention, and the search for efficient biodegradation pathways has become a hot topic. The aim of this study was to screen mangrove sediment and surface water for bacteria capable of degrading polyethylene (PE) and polypropylene (PP) MPs. In this study, two strains of PE-degrading bacteria and two strains of PP-degrading candidate bacteria were obtained from mangrove, named Pseudomonas sp. strain GIA7, Bacillus cereus strain GIA17, Acinetobacter sp. strain GIB8, and Bacillus cereus strain GIB10. The results showed that the degradation rate of the bacteria increased gradually with the increase in degradation time for 60 days. Most of the MP-degrading bacteria had higher degradation rates in the presence of weak acid. The appropriate addition of Mg2+ and K+ was favorable to improve the degradation rate of MPs. Interestingly, high salt concentration inhibited the biodegradation of MPs. Results of scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier-transform infrared spectroscopy (FTIR) indicated the degradation and surface changes of PP and PE MPs caused by candidate bacteria, which may depend on the biodegradation-related enzymes laccase and lipase. Our results indicated that these four bacterial strains may contribute to the biodegradation of MPs in the mangrove environment.

Isolation of marine polyethylene (PE)-degrading bacteria and its potential degradation mechanisms

Microbial degradation of polyethylene (PE) offers a promising solution to plastic pollution in the marine environment, but research in this field is limited. In this study, we isolated a novel marine strain of Pseudalkalibacillus sp. MQ-1 that can degrade PE. Scanning electron microscopy and water contact angle results showed that MQ-1 could adhere to PE films and render them hydrophilic. Analyses using X-ray diffraction, fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy showed a decrease in relative crystallinity, the appearance of new functional groups and an increase in the oxygen-to‑carbon ratio of the PE films, making them more susceptible to degradation. The results of gel permeation chromatography and liquid chromatography-mass spectrometry indicated the depolymerization of the long PE chains, with the detection of an intermediate, decanediol. Furthermore, genome sequencing was employed to investigate the underlying mechanisms of PE degradation. The results of genome sequencing analysis identified the genes associated with PE degradation, including cytochrome P450, alcohol dehydrogenase, and aldehyde dehydrogenase involved in the oxidative reaction, monooxygenase related to ester bond formation, and esterase associated with ester bond cleavage. In addition, enzymes involved in fatty acid metabolism and intracellular transport have been identified, collectively providing insights into the metabolic pathway of PE degradation.

Application of metal-organic frameworks for photocatalytic degradation of microplastics: Design, challenges, and scope

Microplastics (MPs), plastic particles smaller than 5 mm, are pervasive pollutants challenging wastewater treatment due to their size and hydrophobicity. They infiltrate freshwater, marine, and soil environments, posing ecological threats. In marine settings, MPs ingested by organisms cause cytokine release, cellular and DNA damage, and inflammation. As MPs enter the food chain and disrupt biological processes, their degradation is crucial. While biodegradation, pyrolysis, and chemical methods have been extensively studied, the use of metal-organic frameworks (MOFs) for MP pollution mitigation is underexplored. In this study, we explored the photocatalytic degradation mechanisms of MPs by MOFs in aquatic environments. We analyzed the hydrolysis, oxidation, and adsorption processes, while focusing on the environmentally friendly and cost-effective photocatalytic approach. Additionally, we analyzed the literature on MP decomposition for various types of MOFs, providing a detailed understanding of the degradation mechanisms specific to each MOF. Furthermore, we evaluated the degradation efficiencies of different MOFs and discussed the challenges and limitations in their application. Our study highlights the need for an integrated approach that involves the application of MOFs while considering environmental factors and safety concerns to develop effective MP degradation models. This review provides a framework for developing reliable photocatalytic materials with high MP removal and degradation efficiencies, thereby promoting the use of MOFs for marine plastic pollution mitigation.

Effects of polypropylene micro(nano)plastics on soil bacterial and fungal community assembly in saline-alkaline wetlands

Microplastic pollution is a major environmental threat, especially to terrestrial ecosystems. To better understand the effects of microplastics on soil microbiota, the influence of micro- to nano-scale polypropylene plastics was investigated on microbial community diversity, functionality, co-occurrence, assembly, and their interaction with soil-plant using high-throughput sequencing approaches and multivariate analyses. The results showed that polypropylene micro/nano-plastics mainly reduced bacterial diversity, not fungal, and that plastic size had a stronger effect than concentration on the assembly of microbial communities. Nano-plastics decreased the complexity and connectivity of both bacterial and fungal networks compared to micro-plastics. Moreover, bacteria were more sensitive and deterministic to polypropylene micro/nano-plastic stress than fungi, as shown by their different growth rates, guanine-cytosine content, and cell structure. Interestingly, the dominant ecological process for bacteria shifted from stochastic drift to deterministic selection with polypropylene micro/nano-plastic exposure. Furthermore, nano-plastics directly or indirectly disrupted the interactions within intra-microbes and between soil-bacteria-plant by altering soil nutrients and stoichiometry (C:N:P) or plant diversity. Collectively, the results indicate that polypropylene nano-plastics pose more ecological risks to soil microbes and their plant-soil interactions. This study sheds light on the potential ecological consequences of polypropylene micro/nano-plastic pollution in terrestrial ecosystems.

Biodegradation of four polyolefin plastics in superworms (Larvae of Zophobas atratus) and effects on the gut microbiome

Recent studies have demonstrated superworms (larvae of Zophobas atratus) ability to degrade polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), and polypropylene (PP) within their digestive system. This study aimed to compare the ability of superworms to degrade the above four polyolefin plastics over a duration of 30 days. In this study, the degradation rate of PE was the highest, and the final average weight of superworms, as well as the final plastic mass loss consumed by them, significantly increased (73.38 % and 52.33 %, respectively) when PE was fed with wheat bran (1:1 [w/w]). FTIR and TGA indicated the occurrence of oxidation and biodegradation processes in the four polyolefin plastics when exposed to superworms. In addition, the molecular weights (Mw and Mn) of excreted polymer residues decreased by 3.1 % and 2.87 % in PE-fed superworms, suggesting that the depolymerization of PE was not entirely dependent on the gut microbial community. The analysis of the gut microbial communities revealed that the dominant microbial community were different for each type of plastic. The results indicate that the gut microbiome of superworms exhibited remarkable adaptability in degrading various types of plastics, and the intake preferences and efficiency of different plastics are associated with different dominant microbial community species.