Microbial degradation and other environmental aspects of microplastics/plastics

Genome analysis of a plastisphere-associated Oceanimonas sp. NSJ1 sequenced on Nanopore MinION platform

Oceanimonas sp. NSJ1 was isolated from macroplastic debris collected previously from Junput, an intertidal beach, facing the northeast coastal Bay of Bengal of the Northern Indian Ocean. The genome of this isolate is closely related to Oceanimonas doudoroffii with a genome size of 3.56 Mbp. The genome annotation confirmed the presence of 5919 total genes, out of which 5809 were CDSs (coding sequences) and all are protein-coding. The genome codes for 110 RNA with 25 rRNA, 84 tRNA (transfer RNA), and one tmRNA (transfer-messenger RNA). Analyses of the annotated genome of Oceanimonas sp. NSJ1 revealed the presence of enzymes involved in the degradation of polycyclic aromatic hydrocarbons. The presence of phthalate 4,5-dioxygenase oxygenase reductase subunit pht2 within the genome also highlights the novelty of this isolate and future functional potential for studying phthalate degradation in marine environment.

Unraveling the potential human health risks from used disposable face mask-derived micro/nanoplastics during the COVID-19 pandemic scenario: A critical review

With the global spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), disposable face masks (DFMs) have caused negative environmental impacts. DFMs will release microplastics (MPs) and nanoplastics (NPs) during environmental degradation. However, few studies reveal the release process of MPs/NPs from masks in the natural environment. This review presents the current knowledge on the abiotic and biotic degradation of DFMs. Though MPs and NPs have raised serious concerns about their potentially detrimental effects on human health, little attention was paid to their impacts on human health from DFM-derived MPs and NPs. The potential toxicity of mask-derived MPs/NPs, such as gastrointestinal toxicity, pneumotoxicity, neurotoxicity, hepatotoxicity, reproductive and transgenerational toxicity, and the underlying mechanism will be discussed in the present study. MPs/NPs serve as carriers of toxic chemicals and pathogens, leading to their bioaccumulation and adverse effects of biomagnification by food chains. Given human experiments are facing ethical issues and animal studies cannot completely reveal human characteristics, advanced human organoids will provide promising models for MP/NP risk assessment. Moreover, in-depth investigations are required to identify the release of MPs/NPs from discarded face masks and characterize their transportation through the food chains. More importantly, innovative approaches and eco-friendly strategies are urgently demanded to reduce DFM-derived MP/NP pollution.

Occurrence of polycyclic aromatic hydrocarbons, microplastics and biofilms in Alqueva surface water at touristic spots

Freshwater pollution is a huge concern. A study aiming to evaluate physico-chemical characteristics, microbiota, occurrence of two groups of persistent environmental pollutants with similar chemical properties (polycyclic aromatic hydrocarbons- PAHs and microplastics - MPs) in Alqueva's surface water was performed during 2021. Water samples were collected at three spots related to touristic activities (two beaches and one marina) during the Winter, Spring, Summer and Autumn seasons. In addition, the presence of biofilms on plastic and natural materials (stone, wood/ vegetal materials) were assessed and compared. Water quality based on physicochemical parameters was acceptable with a low eutrophication level. PAHs concentration levels were lower than the standard limits established for surface waters by international organizations. However, carcinogenic compounds were detected in two sampling locations, which can pose a problem for aquatic ecosystems. PAHs profiles showed significant differences when comparing the dry seasons with the rainy seasons, with a higher number of different compounds detected in Spring. Low molecular weigh compounds, usually associated with the atmospheric deposition and petroleum contamination, were more prevalent. MPs were detected in all samples except one during the Winter season. The polymers detected were poly(methyl-2-methylpropenoate), polystyrene, polyethylene terephthalate, polyamide, polypropylene, styrene butadiene, polyvinyl chloride and low /high density polyethylene with the last being the most frequent. Biofilms were more often detected on plastics than on natural materials. In addition, biofilms detected on plastics were more complex with higher microbial diversity (e.g., bacteria, fungi/yeast and phytoplancton organisms) and richer in extrapolymeric material. Based on morphological analysis a good agreement between microbiota and microorganism present in the biofilms was found. Among microbiota were identified microorganisms previously linked to plastic and PAHs detoxification suggesting the need for further studies to evaluate the viability of using biofilms as part of a green bioremediation strategy to mitigate water pollution.

Nanoplastics: Detection and impacts in aquatic environments - A review

The rise in the global production of plastics has led to severe concerns about the impacts of plastics in aquatic environments. Although plastic materials degrade over extreme long periods, they can be broken down through physical, chemical, and/or biological processes to form microplastics (MPs), defined here as particles between 1 μm and 5 mm in size, and later to form nanoplastics (NPls), defined as particles <1 μm in size. We know little about the abundance and effects of NPls, even though a lot of research has been conducted on the ecotoxicological impacts of MPs on both aquatic biota. Nevertheless, there is evidence that NPls can both bypass the cell membranes of microorganisms and bioaccumulate in the tissues and organs of higher organisms. This review analyzes 150 publications collected by searching through the databases Web of Science, SCOPUS, and Google Scholar using keywords such as nanoplastics*, aquatic*, detection*, toxic*, biofilm*, formation*, and extracellular polymeric substance* as singular or plural combinations. We highlight and critically synthesize current studies on the formation and degradation of NPls, NPls' interactions with aquatic biota and biofilm communities, and methods of detection. One reason for the missing data and studies in this area of research is the lack of a protocol for the detection of, and suitable methods for the characterization of, NPls in the field. Our primary aim is to identify gaps in knowledge throughout the review and define future directions of research to address the impacts of NPls in aquatic environments. The development of consistent and standardized sets of procedures would address the gaps in knowledge regarding the formation and degradation of NPls as well as sampling and characterizing natural NPls needed to observe the full extent of NPls on aquatic biota and biofilm communities.

Recent advances on the effects of microplastics on elements cycling in the environment

Microplastics (<5 mm) are an emerging pollutant which have received increasing concern in recent years. Microplastics pose a serious hazard and potential risk to the environment due to their migration, transformation, adsorption and degradation properties. The effects of different types of microplastics on the elemental cycles (carbon, nitrogen and phosphorus cycles) in ecosystems were comprehensively summarized. The impacts of microplastics on the element cycle occur mainly in the soil environment and to less extent in other environments. Microplastics affect carbon sources, carbon dioxide (CO₂) emissions, and carbon conversion processes, mainly by affecting plant and animal activities, changing gene abundance, enzyme activity, and microbial community composition. Microplastics can affect nitrogen sources, nitrogen fixation, ammonification, nitrification and denitrification processes by changing gene abundance, enzyme activity and microbial community composition. Microplastics can also influence phosphorus content and phosphorus conversion processes by stimulating enzyme activity and changing the composition of microbial communities. Future research needs to analyze the coupling of multiple microplastics and influencing factors on elemental cycling processes. This work provides a better view of the impacts of microplastics on element cycles and the interaction between microplastics and organisms.

Microbial community niches on microplastics and prioritized environmental factors under various urban riverine conditions

Microplastics (MPs) provide habitats to microorganisms in aquatic environments; distinct microbial niches have recently been elucidated. However, there is little known about the microbial communities on MPs under urban riverine conditions, in which environmental factors fluctuate. Therefore, this study investigated MP biofilm communities under various urban riverine conditions (i.e., organic content, salinity, and dissolved oxygen (DO) concentration) and evaluated the prioritized factors affecting plastisphere communities. Nine biofilm-forming reactors were operated under various environmental conditions. Under all testing conditions, biofilms grew on MPs with decreasing bacterial diversity. Interestingly, biofilm morphology and bacterial populations were driven by the environmental parameters. We found that plastisphere community structures were grouped according to the environmental conditions; organic content in the water was the most significant factor determining MP biofilm communities, followed by salinity and DO concentration. The principal plastisphere communities were Proteobacteria, Bacteroidetes, Cyanobacteria, and Firmicutes phyla. In-depth analyses of plastisphere communities revealed that biofilm-forming and plastic-degrading bacteria were the predominant microbes. In addition, potential pathogens were majorly discovered in the riverine waters with high organic content. Our results suggest that distinct plastisphere communities coexist with MP particles under certain riverine water conditions, implying that the varied MP biofilm communities may affect urban riverine ecology in a variety of ways.

Development of solid agents of the diphenyl ether herbicide degrading bacterium Bacillus sp. Za based on a mixed organic fertilizer carrier

The long-term and widespread use of diphenyl ether herbicides has caused serious soil residue problems and threatens the agricultural ecological environment. The development of biodegrading agents using high-efficiency degrading strains as pesticide residue remediation materials has been widely recognized. In this study, the strain Bacillus sp. Za was used to prepare solid agents for the remediation of diphenyl ether herbicides-contaminated soil. The ratio of organic fertilizer was 1:3 (pig manure: cow dung), the inoculum amount of Za was 10%, the application amount of solid agents was 7%, and the application mode was mixed application, all of which were the most suitable conditions for solid agents. After the solid agents were stored for 120 days, the amount of Za remained above 10⁸ CFU/g. The degradation rates of the solid agents for lactofen, bifenox, fluoroglycofen, and fomesafen in soil reached 87.40, 82.40, 78.20, and 65.20%, respectively, on the 7th day. The application of solid agents alleviated the toxic effect of lactofen residues on maize seedlings. A confocal laser scanning microscope (CLSM) was used to observe the colonization of Za-gfp on the surface of maize roots treated in the solid agents, and Za-gfp mainly colonized the elongation zone and the mature area of maize root tips, and the colonization time exceeded 21 days. High-throughput sequencing analysis of soil community structural changes in CK, J (solid agents), Y (lactofen), and JY (solid agents + lactofen) groups showed that the addition of solid agents could restore the bacterial community structure in the rhizosphere soil of maize seedlings. The development of solid agents can facilitate the remediation of soil contaminated with diphenyl ether herbicide residues and improve the technical level of the microbial degradation of pesticide residues.

The Relationship between Brachionus calyciflorus-Associated Bacterial and Bacterioplankton Communities in a Subtropical Freshwater Lake

Zooplankton bodies are organic-rich micro-environments that support fast bacterial growth. Therefore, the abundance of zooplankton-associated bacteria is much higher than that of free-living bacteria, which has profound effects on the nutrient cycling of freshwater ecosystems. However, a detailed analysis of associated bacteria is still less known, especially the relationship between those bacteria and bacterioplankton. In this study, we analyzed the relationships between Brachionus calyciflorus-associated bacterial and bacterioplankton communities in freshwater using high-throughput sequencing. The results indicated that there were significant differences between the two bacterial communities, with only 29.47% sharing OTUs. The alpha diversity of the bacterioplankton community was significantly higher than that of B. calyciflorus-associated bacteria. PCoA analysis showed that the bacterioplankton community gathered deeply, while the B. calyciflorus-associated bacterial community was far away from the whole bacterioplankton community, and the distribution was relatively discrete. CCA analysis suggested that many environmental factors (T, DO, pH, TP, PO₄^3-, NH₄⁺, and NO₃^-) regulated the community composition of B. calyciflorus-associated bacteria, but the explanatory degree of variability was only 37.80%. High-throughput sequencing revealed that Raoultella and Delftia in Proteobacteria were the dominant genus in the B. calyciflorus-associated bacterial community, and closely related to the biodegradation function. Moreover, several abundant bacterial members participating in carbon and nitrogen cycles were found in the associated bacterial community by network analysis. Predictive results from FAPROTAX showed that the predominant biogeochemical cycle functions of the B. calyciflorus-associated bacterial community were plastic degradation, chemoheterotrophy, and aerobic chemoheterotrophy. Overall, our study expands the current understanding of zooplankton-bacteria interaction and promotes the combination of two different research fields.

Detection of Environmental Microfiber Pollutants through Vibrational Spectroscopic Techniques: Recent Advances of Environmental Monitoring and Future Prospects

A robust environmental monitoring system is highly essential for the instant detection of environmental microfiber pollutants for the sustainable management of the environment and human health. The extent of microfiber pollution is growing exponentially across the globe in both terrestrial and marine environments. An immediate and accurate environmental monitoring system is crucial to investigate the composition and distribution of these micropollutants. Fourier Transform Infrared Spectroscopy and Raman Spectroscopy are vibrational spectroscopic techniques that have the novel ability to detect microfibers within a minute concentration from diverse environmental samples. The major micropollutants which have been analyzed are polyethylene, polypropylene, nylon 6, polystyrene, and polyethylene terephthalate. After a detailed and critical study of the various aspects of spectroscopic analysis, the review is concluded with a comprehensive discussion of the significance of these robust methods and their application in future aspects for further preventing microfiber pollution in the marine environment. This study highlights the utilities and significance of vibrational spectroscopic detection techniques for the immediate and accurate identification of synthetic microfibers. This review also evaluated the implementation of spectroscopic methods as a precise tool for the characterization and monitoring of microfiber pollutants in the environment.

Decomposition rate and biochemical fate of carbon from natural polymers and microplastics in boreal lakes

Microbial mineralization of organic compounds is essential for carbon recycling in food webs. Microbes can decompose terrestrial recalcitrant and semi-recalcitrant polymers such as lignin and cellulose, which are precursors for humus formation. In addition to naturally occurring recalcitrant substrates, microplastics have been found in various aquatic environments. However, microbial utilization of lignin, hemicellulose, and microplastics as carbon sources in freshwaters and their biochemical fate and mineralization rate in freshwaters is poorly understood. To fill this knowledge gap, we investigated the biochemical fate and mineralization rates of several natural and synthetic polymer-derived carbon in clear and humic lake waters. We used stable isotope analysis to unravel the decomposition processes of different 13C-labeled substrates [polyethylene, polypropylene, polystyrene, lignin/hemicellulose, and leaves (Fagus sylvatica)]. We also used compound-specific isotope analysis and molecular biology to identify microbes associated with used substrates. Leaves and hemicellulose were rapidly decomposed compared to microplastics which were degraded slowly or below detection level. Furthermore, aromatic polystyrene was decomposed faster than aliphatic polyethylene and polypropylene. The major biochemical fate of decomposed substrate carbon was in microbial biomass. Bacteria were the main decomposers of all studied substrates, whereas fungal contribution was poor. Bacteria from the family Burkholderiaceae were identified as potential leaf and polystyrene decomposers, whereas polypropylene and polyethylene were not decomposed.

Uniqueness and Dependence of Bacterial Communities on Microplastics: Comparison with Water, Sediment, and Soil

Revealing the dependence and uniqueness of microbial communities on microplastics could help us better understand the assembly of the microplastic microbial community in river ecosystems. In this study, we investigated the composition and ecological functions of the bacterial community on microplastics from the Three Gorges Reservoir area compared with those in water, sediment, and soil at species-level via full-length 16S rRNA gene sequencing. The results showed that the full-length 16S rRNA sequencing provided more detail and accurate taxa resolution of the bacterial community in microplastics (100%), water (99.90%), sediment (99.95%), and soil (100%). Betaproteobacteriales were the most abundant bacteria in microplastics (14.1%), water (32.3%), sediments (27.2%), and soil (21.0%). Unexpectedly, oligotrophic SAR11 clade was the third abundant bacteria (8.51%) and dominated the ecological functions of the bacterial community in water, but it was less observed on microplastics, with a relative abundance of 2.73×10^-5. However, four opportunistic pathogens identified at the species level were selectively enriched on microplastics. Stenotrophomonas maltophilia was the main opportunistic pathogen on microplastics (0.29%). Sediment rather than soil and water may be contributed mostly to pathogens on microplastics. Moreover, some bacteria species with the biodegradation function of microplastics were enriched on microplastics, such as bacteria Rhodobacter sp., and endemic bacteria Luteimonas sp. The distinct bacteria composition on microplastics enhanced several ecological functions, such as xenobiotics biodegradation, which allows screening the bacteria with the biodegradation function of microplastics through long-term exposure.

Plants oxidative response to nanoplastic

Pollution of the environment with plastic is an important concern of the modern world. It is estimated that annually over 350 million tonnes of this material are produced, wherein, despite the recycling methods, a significant part is deposited in the environment. The plastic has been detected in the industrial areas, as well as farmlands and gardens in many world regions. Larger plastic pieces degraded in time into smaller pieces including microplastic (MP) and nanoplastic particles (NP). Nanoplastic is suggested to pose the most serious danger as due to the small size, it is effectively taken up from the environment by the biota and transported within the organisms. An increasing number of reports show that NP exert toxic effects also on plants. One of the most common plant response to abiotic stress factors is the accumulation of reactive oxygen species (ROS). On the one hand, these molecules are engaged in cellular signalling and regulation of genes expression. On the other hand, ROS in excess lead to oxidation and damage of various cellular compounds. This article reviews the impact of NP on plants, with special emphasis on the oxidative response.

Myco-degradation of microplastics: an account of identified pathways and analytical methods for their determination

Microplastics (MPs) have sparked widespread concern due to their non-degradable and persistent nature in ecosystems. Long-term exposure to microplastics can cause chronic toxicity, including impaired reproduction and malnutrition, threatening biota and humans. Microplastics can also cause ingestion, choking, and entanglement in aquatic populations. Thus, it is crucial to establish remarkably effective approaches to diminish MPs from the environment. In this regard, using fungi for microplastic degradation is beneficial owing to its diverse nature and effective enzymatic system. Extracellular and intracellular enzymes in fungi degrade the plastic polymers into monomers and produce carbon dioxide and water under aerobic conditions whereas methane under anaerobic conditions. Further, fungi also secrete hydrophobins (surface proteins) which serve as a crucial aid in the bioremediation process by promoting substrate mobility and bioavailability. Therefore, the present review provides insight into the mechanism and general pathway of fungal-mediated microplastic degradation. Additionally, analytical techniques for the monitoring of MPs degradation along with the roadblocks and future perspectives have also been discussed. However, more research is required to fully perceive the underlying process of microplastic biodegradation in the environment using fungus, to establish an effective and sustainable practice for its management.

Optimization of Polystyrene Biodegradation by Bacillus cereus and Pseudomonas alcaligenes Using Full Factorial Design

Microplastics (MP) are a global environmental problem because they persist in the environment for long periods of time and negatively impact aquatic organisms. Possible solutions for removing MP from the environment include biological processes such as bioremediation, which uses microorganisms to remove contaminants. This study investigated the biodegradation of polystyrene (PS) by two bacteria, Bacillus cereus and Pseudomonas alcaligenes, isolated from environmental samples in which MPs particles were present. First, determining significant factors affecting the biodegradation of MP-PS was conducted using the Taguchi design. Then, according to preliminary experiments, the optimal conditions for biodegradation were determined by a full factorial design (main experiments). The RSM methodology was applied, and statistical analysis of the obtained models was performed to analyze the influence of the studied factors. The most important factors for MP-PS biodegradation by Bacillus cereus were agitation speed, concentration, and size of PS, while agitation speed, size of PS, and optical density influenced the process by Pseudomonas alcaligenes. However, the optimal conditions for biodegradation of MP-PS by Bacillus cereus were achieved at γ_MP = 66.20, MP size = 413.29, and agitation speed = 100.45. The best conditions for MP-PS biodegradation by Pseudomonas alcaligenes were 161.08, 334.73, and 0.35, as agitation speed, MP size, and OD, respectively. In order to get a better insight into the process, the following analyzes were carried out. Changes in CFU, TOC, and TIC concentrations were observed during the biodegradation process. The increase in TOC values was explained by the detection of released additives from PS particles by LC-MS analysis. At the end of the process, the toxicity of the filtrate was determined, and the surface area of the particles was characterized by FTIR-ATR spectroscopy. Ecotoxicity results showed that the filtrate was toxic, indicating the presence of decomposition by-products. In both FTIR spectra, a characteristic weak peak at 1715 cm⁻¹ was detected, indicating the formation of carbonyl groups (−C=O), confirming that a biodegradation process had taken place.

Synthetic Biology: Bottom-Up Assembly of Molecular Systems

The bottom-up assembly of biological and chemical components opens exciting opportunities to engineer artificial vesicular systems for applications with previously unmet requirements. The modular combination of scaffolds and functional building blocks enables the engineering of complex systems with biomimetic or new-to-nature functionalities. Inspired by the compartmentalized organization of cells and organelles, lipid or polymer vesicles are widely used as model membrane systems to investigate the translocation of solutes and the transduction of signals by membrane proteins. The bottom-up assembly and functionalization of such artificial compartments enables full control over their composition and can thus provide specifically optimized environments for synthetic biological processes. This review aims to inspire future endeavors by providing a diverse toolbox of molecular modules, engineering methodologies, and different approaches to assemble artificial vesicular systems. Important technical and practical aspects are addressed and selected applications are presented, highlighting particular achievements and limitations of the bottom-up approach. Complementing the cutting-edge technological achievements, fundamental aspects are also discussed to cater to the inherently diverse background of the target audience, which results from the interdisciplinary nature of synthetic biology. The engineering of proteins as functional modules and the use of lipids and block copolymers as scaffold modules for the assembly of functionalized vesicular systems are explored in detail. Particular emphasis is placed on ensuring the controlled assembly of these components into increasingly complex vesicular systems. Finally, all descriptions are presented in the greater context of engineering valuable synthetic biological systems for applications in biocatalysis, biosensing, bioremediation, or targeted drug delivery.

Distribution, sources, migration, influence and analytical methods of microplastics in soil ecosystems

Microplastics are ubiquitous in soil ecosystems all over the world through source and migration. It is even estimated that the content of microplastics in terrestrial ecosystems exceeds the number of microplastics entering sea ecosystems. However, compared with the research on microplastics in marine ecosystems, the research and discussion on microplastics in soil ecosystems are still less. Transportation, film mulching and sewage sludge are three main sources of soil microplastics. The abundance, polymer type, size and shape of the microplastics are related to the source and they help to clarify the source. The characteristics of microplastics, farming measures, soil animal activities and other factors promote the migration of microplastics, which bring new challenges to the soil ecosystems and humans. This article summarizes the latest research findings on the effects of soil microplasticity on soil properties, plants, animals and microorganisms. The analysis methods of microplastics in soil can refer to the analysis methods of microplastics of aquatic sediments, because soil and aquatic sediments are similar, both of which are complex solid substrates. At present, the development of analytical methods is limited due to the complex matrix of soil and the small volume of microplastics, which requires continuous development and innovation. Through the summary and analysis of related articles, this article reviews the distribution, sources, migration, influence and analysis methods of soil microplastics. This article also critically analyzes the deficiencies in the studies of microplastics in the soil ecosystems, and made some suggestions for future work. The microplastics in soil ecosystems need further research and summary, which will help people further understand the potential hazards of microplastics.

Interactions of microplastics with organic, inorganic and bio-pollutants and the ecotoxicological effects on terrestrial and aquatic organisms

As emerging contaminants, microplastics (MPs) have attracted global attention. They are a potential risk to organisms, ecosystems and human health. MPs are characterized by small particle sizes, weak photodegradability, and are good environmental carriers. They can physically adsorb or chemically react with organic, inorganic and bio-pollutants to generate complex binary pollutants or change the environmental behaviors of these pollutants. We systematically reviewed the following aspects of MPs: (i) Adsorption of heavy metals and organic pollutants by MPs and the key environmental factors affecting adsorption behaviors; (ii) Enrichment and release of antibiotic resistance genes (ARGs) on MPs and the effects of MPs on ARG migration in the environment; (iii) Formation of "plastisphere" and interactions between MPs and microorganisms; (iv) Ecotoxicological effects of MPs and their co-exposures with other pollutants. Finally, scientific knowledge gaps and future research areas on MPs are summarized, including standardization of study methodologies, ecological effects and human health risks of MPs and their combination with other pollutants.

The effects of weathering-induced degradation of polymers in the microplastic study involving reduction of organic matter

The analysis of microplastics in complex environmental samples requires the use of chemicals to reduce the organic matrix. This procedure should be evaluated in terms of the preservation of the microplastic's integrity, typically done with pristine reference microplastics. However, real microplastics are most likely degraded due to weathering, so pristine reference microplastics might not depict the appropriateness of the process. This study performed a purification process using sodium dodecyl sulfate and hydrogen peroxide on sewage sludge containing LLDPE, HDPE, PP, PS, PET, PA66 and SBR samples exposed to simulated environmental weathering. The degradation of the polymers was assessed by analyzing surface morphology, mass variation, and mechanical, thermal and chemical properties. Comparison with pristine polymers revealed that the purification process can lead to more detrimental effects if the polymers are weathered. After the purification process, some important observations were: 1) LLDPE, PP and SBR surfaces had cracks in the weathered samples that were not observed in the pristine samples, 2) weathered LLDPE, PP and PA66 experienced greater mass loss than pristine, 3) the fragmentation propensity of weathered LLDPE, HDPE, PP, PS and SBR increased compared to pristine samples and 4) the main characteristic peaks in FTIR spectrum could be identified and used for chemical identification of most polymers for pristine and weathered samples. Based on the findings of this study, when analyzing the efficiency and adequacy of a purification process with methods based on surface morphology, mass variation and particle counting indicators, it is recommended to consider the differences that potentially arise between pristine and weathered microplastics, especially for polyolefins (PEs and PP).

Elimination of microplastics from the aquatic milieu: A dream to achieve

Microplastics (MPs) have become a significant source of concern as they have emerged as a widespread pollutant that harms the aquatic environment. It has become an enormous challenge, having the capacity to biomagnify and eventually affect human health, biodiversity, aquatic animals, and the environment. This review provides in-depth knowledge of how MPs interact with different toxic organic chemicals, antibiotics, and heavy metals in the aquatic environment and its consequences. Membrane technologies like ultrafiltration (UF), nanofiltration (NF), microfiltration (MF), and dynamic membranes can be highly effective techniques for the removal of MPs. Also, hybrid membrane techniques like advanced oxidation processes (AOPs), membrane fouling, electrochemical processes, and adsorption processes can be incorporated for superior efficiency. The review also focuses on the reactor design and performance of several membrane-based filters and bioreactors to develop practical, feasible, and sustainable membrane technologies. The main aim of this work is to throw light on the alarming scenario of microplastic pollution in the aquatic milieu and strategies that can be adopted to tackle it.

Recent advances in the breakdown of microplastics: strategies and future prospectives

Microplastics pollution is becoming a major environmental issue, and exposure to microplastics has been associated with numerous adverse results to both the ecological system and humans. This work summarized the state-of-the-art developments in the breakdown of microplastics, including natural weathering, catalysts-assisted breakdown and biodegradation. Characterization techniques for microplastic breakdown involve scanning electron microscopy, Fourier infrared spectroscopy, X-ray photoelectron spectroscopy, etc. Bioavailability and adsorption capacity of microplastics may change after they are broken down, therefore leading to variety in microplastics toxicity. Further prospectives for should be focused on the determination and toxicity evaluation of microplastics breakdown products, as well as unraveling uncultivable microplastics degraders via cultivation-independent approaches. This work benefits researchers interested in environmental studies, particularly the removal of microplastics from environmental matrix.

Microplastics in dust from different indoor environments

Microplastics (MPs) are present in global indoor dust, which is an important source of MPs for humans. However, few researchers have investigated differences in the abundance and characteristics of MPs in dust in different indoor environments. In this study, we found that residential apartments (mean: 1174 MPs/g; n = 47) had the highest abundance of MPs in indoor dust samples, followed by offices (896 MPs/g; n = 50), business hotels (843 MPs/g; n = 53), university dormitories (775 MPs/g; n = 48), and university classrooms (209 MPs/g; n = 44). The predominant shape of MPs was fiber in most indoor dust samples. The main size fraction of the MPs in the indoor dust samples from university classrooms and business hotels was 201-500 μm, and it was 501-1000 μm in those from offices, university dormitories, and residential apartments. The main MP polymer in indoor dust samples from business hotels, university dormitories, and residential apartments was polyester, whereas those from offices and university classrooms were mainly polyethylene and polypropylene. We calculated the estimated daily intake (EDI) of MPs through the inhalation of indoor dust, and found that infants (7.4 MPs/kg bw/day) had a higher mean EDI of MPs than toddlers (1.4 MPs/kg bw/day), children (0.49 MPs/kg bw/day), adults (0.23 MPs/kg bw/day), and university students (0.22 MPs/kg bw/day). To the best of our knowledge, we are the first to report differences in MP occurrence in dust samples from different indoor environments, and our findings provide a more accurate understanding of exposure risks of MPs to humans.

Microplastics exposure affects neural development of human pluripotent stem cell-derived cortical spheroids

Plastics have been part of our ecosystem for about a century and their degradation by different environmental factors produce secondary microplastics (MPs). To date, the impact of MPs on human health has not been well investigated. To understand the possible effects of polystyrene-MPs (PS-MPs) on the human brain, a 3D model of human forebrain cortical spheroids has been derived, which mimics early development of human cerebral cortex. The spheroids were exposed to 100, 50, and 5 µg/mL of 1 µm and 10 µm PS-MPs during day 4-10 and day 4-30. The short-term MP exposure showed the promoted proliferation and high gene expression of Nestin, PAX6, ATF4, HOXB4 and SOD2. For long-term exposure, reduced cell viability was observed. Moreover, changes in size and concentration of PS-MPs altered the gene expression of DNA damage and neural tissue patterning. In particular, β-tubulin III, Nestin, and TBR1/TBR2 gene expression decreased in PS-MP treated conditions compare to the untreated control. The results of this study suggest that the size- and concentration-dependent exposure to PS-MPs can adversely affect embryonic brain-like tissue development in forebrain cerebral spheroids. This study has significance in assessing environmental factors in neurotoxicity and degeneration in human.

Characteristics of microplastic pollution and analysis of colonized-microbiota in a freshwater aquaculture system

The microbial communities associated with microplastics (MPs) and their ambient environments have received wide attention. Although previous studies have reported the differences of microbial communities between MPs and natural environment or substrates, the effects of MPs on microbial balance and functions in ambient water remain unclear, particularly for aquaculture water. Here, we investigated the MPs pollution in farm ponds of grass carp located in the Foshan City of Guangdong Province and reported the distinction of bacterial structures, functions, and complexity between microbiota on MPs and in water. MPs with an average abundance of 288.53 ± 74.27 items/L in pond water were mostly fibers and cellulose, mainly transparent and in size of 0.5-1 mm. Structures and functions of bacterial communities on MPs significantly differed from that in pond water. A large number of enriched or depleted OTUs on MPs compared with water belong to the phylum Proteobacteria, the predominant phylum in microbial communities on MPs and in water. Some species included in the phylum Proteobacteria have been shown to be cellulose-degrading and pathogenic. Microbiota on MPs exhibited higher species richness and diversity as well as a more complex network than that in water, illustrating MPs as a distinct habitat in the aquaculture system.

Microplastic pollution in fragile coastal ecosystems with special reference to the X-Press Pearl maritime disaster, southeast coast of India

Microplastics (MPs) are a global environmental concern and pose a serious threat to marine ecosystems. This study aimed to determine the abundance and distribution of MPs in beach sediments (12 beaches), marine biota (6 beaches) and the influence of microbes on MPs degradation in eco-sensitive Palk Bay and Gulf of Mannar coast. The mean MP abundance 65.4 ± 39.8 particles/m² in beach sediments; 0.19 ± 1.3 particles/individual fish and 0.22 ± 0.11 particles g^-1 wet weight in barnacles. Polyethylene fragments (33.4%) and fibres (48%) were the most abundant MPs identified in sediments and finfish, respectively. Histopathological examination of fish has revealed health consequences such as respiratory system damage, epithelial degradation and enterocyte vacuolization. In addition, eight bacterial and seventeen fungal strains were isolated from the beached MPs. The results also indicated weathering of MPs due to microbial interactions. Model simulations helped in tracking the fate and transboundary landfall of spilled MPs across the Indian Ocean coastline after the X-Press Pearl disaster. Due to regional circulations induced by the monsoonal wind fields, a potential dispersal of pellets has occurred along the coast of Sri Lanka, but no landfall and ecological damage are predicted along the coast of India.

Chemical and microbiological changes on the surface of microplastic after long term exposition to different concentrations of ammonium in the environment

The increasing production of plastic in the world has resulted in the widespread pollution of the environment with microplastics (MP). MP enter facilities such as wastewater treatment plants or landfills characterized by various ammonium concentrations. The aim of this study was to determine the structure of the microbial community on MP surfaces at various concentrations of ammonium nitrogen, and in particular, to identify microorganisms capable of polyethylene terephthalate (PET) degradation. Moreover, changes in the chemical characteristics of the MP surface resulting from microbial activity were also investigated, and the potential of MP to serve as a vector for pollutants was determined. The tests were carried out in a reactor filled with PET for a period of 260 days. The experiment was carried out in 3 phases: in I and III phase, the concentration of N-NH₄ was about 70 mg/L, while in II phase, it was about 430 mg/L. On the MP surface, biofilm-forming microorganisms from the genera Rhodococcus, Pseudomonas and Xantomonas were identified at the lower ammonium concentration. At this concentration, MP-degraders belonging to genera Acidovorax, Gordonia, Pseudomonas, Sphingomonas, and Sphingopyxis were identified in the biofilm. At the higher N-NH₄ concentration, the biomass was enriched with bacteria from genera Nitrosospira, Nitrosomonas and Terrimonas, and the number of microorganisms with the potential to degrade MP decreased. Analysis of the MP surface during the experiment has showed the loss of carbonyl groups and formation of carboxyl and hydroxyl groups, which indicated the degradation of MP. Independent of the ammonium concentration in the environment, MP was a carrier of pathogenic microorganisms from the genera Mycobacterium, Enterobacter and Brevundimonas.

Substitute for polyethylene (PE) films: A novel cow dung-based liquid mulch on silage cornfields

To prevent soil pollution caused by polyethylene (PE) films in the central region of Gansu, China, liquid mulching made from cow dung (CDLM) was trailed in silage maize fields. The degradation of CDLM and PE films, soil temperature, soil organic matter content, silage maize yield and water use efficiency (WUE) were evaluated for three years (2018–2020). The degradability of CDLM has been found to be much stronger than the one of PE films, with CDLM degrading 40–60 days after sowing and finishing around 100 days. CDLM had a lower insulating impact than PE films but a higher insulating effect than non-mulching films as the control (CK); CDLM could successfully increase soil organic matter, with a total increase of 1.01% over three years. CDLM increased silage maize yield by 6.2% compared to PE films and 17.2% compared to CK. Consequently, CDLM may be an interesting alternative to PE films for enhancing silage maize yield while decreasing soil contamination.

Insights into the removal of polystyrene nanoplastics using the contaminated corncob-derived mesoporous biochar from mining area

Nanoplastic has become a prominent threat to the aquatic ecosystem, and the cost-effective technologies for controlling that are still insufficient. The aim of this study is to use contaminated corncobs collected in mining area to prepare functional mesoporous biochar (MBC) and to investigate its ability to remove polystyrene nanoplastics (PSNPs) from water. The adsorption of PSNPs by MBC could be better described by the Sips isotherm and followed the second-order kinetics, with the theoretical maximum adsorption capacity of MBC for PSNPs was 56.02 mg·g^-1. Then the PSNPs adsorbed on MBC could be hydrothermally degraded and the biochar could be simultaneously regenerated. The ability was affected by various factors, including oxygen-containing functional groups, metallic components, superoxide radicals and holes. The degradation products were dominated as low-molecule-weight oligomers and the main possible pathways involved scission, hydrolysis and radical reaction. The findings highlight the great potential of biochar prepared using contaminated biowaste in mining area to remove the nanoplastic pollutants in the aqueous environment.

Current progress on plastic/microplastic degradation: Fact influences and mechanism

Plastic pollution, particularly non-degradable residual plastic films and microplastics (MPs), is a serious environmental problem that continues to worsen each year. Numerous studies have characterized the degradation of plastic fragments; however, there is known a lack of about the state of current physicochemical biodegradation methods used for plastics treatment and their degradation efficiency. Therefore, this review explores the effects of different physicochemical factors on plastics/MPs degradation, including mechanical comminution, ultraviolet radiation, high temperature, and pH value. Further, this review discusses different mechanisms of physicochemical degradation and summarizes the degradation efficiency of these factors under various conditions. Additionally, the important role of enzymes in the biodegradation mechanism of plastics/MPs is also discussed. Collectively, the topics discussed in this review provide a solid basis for future research on plastics/MPs degradation methods and their effects.

Bioleaching of Typical Electronic Waste-Printed Circuit Boards (WPCBs): A Short Review

The rapid pace of innovations and the frequency of replacement of electrical and electronic equipment has made waste printed circuit boards (WPCB) one of the fastest growing waste streams. The frequency of replacement of equipment can be caused by a limited time of proper functioning and increasing malfunctions. Resource utilization of WPCBs have become some of the most profitable companies in the recycling industry. To facilitate WPCB recycling, several advanced technologies such as pyrometallurgy, hydrometallurgy and biometallurgy have been developed. Bioleaching uses naturally occurring microorganisms and their metabolic products to recover valuable metals, which is a promising technology due to its cost-effectiveness, environmental friendliness, and sustainability. However, there is sparse comprehensive research on WPCB bioleaching. Therefore, in this work, a short review was conducted from the perspective of potential microorganisms, bioleaching mechanisms and parameter optimization. Perspectives on future research directions are also discussed.

The fate of missing ocean plastics: Are they just a marine environmental problem?

The fate of mismanaged plastic waste released into oceans (ocean plastics) remains a topic of debate, where the mass imbalance between the leakage and abundance in the world's oceans appears paradoxical. In the present study, a budget for ocean plastic mass was estimated based on a combination of numerical particle tracking and linear mass-balance models, both validated using a worldwide ocean plastic dataset. Integrating the time series of worldwide macroplastic emission from both rivers and the fisheries industry over the period 1961-2017 yielded a total mass of 25.3 million metric tonnes (MMT). Macro- and microplastics currently floating in the oceans, and microplastics on beaches, each account for 3-4% of the ocean plastics emitted worldwide to date. Overall, 23.4% of ocean plastics were macroplastics on beaches. Meanwhile, 66.7% of ocean plastics were heavier than seawater or microplastics removed from the upper ocean and beaches, which are difficult to monitor under current observation frameworks adopted worldwide. However, the present study on ocean plastics suggested that the whole ocean plastics accounted for only 4.7% of mismanaged plastic waste (542.2 MMT) generated between the 1960s and today.

Microplastics shape microbial communities affecting soil organic matter decomposition in paddy soil

Microplastics (MPs) can alter microbial communities and carbon (C) cycling in agricultural soils. However, the mechanism by which MPs affect the decomposition of microbe-driven soil organic matter remains unknown. We investigated the bacterial community succession and temporal turnover during soil organic matter decomposition in MP-amended paddy soils (none, low [0.01% w/w], or high [1% w/w]). We observed that MPs reduced the CO₂ efflux rate on day 3 and subsequently promoted it on day 15 of incubation. This increased CO₂ emission in MP-amended soil may be related to (i) enhanced hydrolase enzyme activities or; (ii) shifts in the Shannon diversity, positive group interactions, and temporal turnover rates (from 0.018 to 0.040). CO₂ efflux was positively correlated (r > 0.8, p < 0.01) with Ruminiclostridium_1, Mobilitalea, Eubacterium xylanophilum, Sporomusa, Anaerobacteriu, Papillibacter, Syntrophomonadaceae, and Ruminococcaceae_UCG_013 abundance in soil with high MPs, indicating that these genera play important roles in soil organic C mineralization. These results demonstrate how microorganisms adapt to MPs and thus influence the C cycle in MP-polluted paddy ecosystems.

Research and Application of Polypropylene Carbonate Composite Materials: A Review

The greenhouse effect and plastic pollution caused by the accumulation of plastics have led to a global concern for environmental protection, as well as the development and application of biodegradable materials. Polypropylene carbonate (PPC) is a biodegradable polymer with the function of "carbon sequestration", which has the potential to mitigate the greenhouse effect and the plastic crisis. It has the advantages of good ductility, oxygen barrier and biocompatibility. However, the mechanical and thermal properties of PPC are poor, especially the low thermal degradation temperature, which limits its industrial use. In order to overcome this problem, PPC can be modified using environmentally friendly materials, which can also reduce the cost of PPC-based products to a certain extent and enhance their competitiveness in terms of improving their mechanical and thermal properties. In this paper, we present different perspectives on the synthesis, properties, degradation, modification and post-modification applications of PPC. The modification part mainly introduces the influence of inorganic materials, natural polymer materials and degradable polymers on the performance of PPC. It is hoped that this work will serve as a reference for the early promotion of PPC.

Lessons From Insect Fungiculture: From Microbial Ecology to Plastics Degradation

Anthropogenic activities have extensively transformed the biosphere by extracting and disposing of resources, crossing boundaries of planetary threat while causing a global crisis of waste overload. Despite fundamental differences regarding structure and recalcitrance, lignocellulose and plastic polymers share physical-chemical properties to some extent, that include carbon skeletons with similar chemical bonds, hydrophobic properties, amorphous and crystalline regions. Microbial strategies for metabolizing recalcitrant polymers have been selected and optimized through evolution, thus understanding natural processes for lignocellulose modification could aid the challenge of dealing with the recalcitrant human-made polymers spread worldwide. We propose to look for inspiration in the charismatic fungal-growing insects to understand multipartite degradation of plant polymers. Independently evolved in diverse insect lineages, fungiculture embraces passive or active fungal cultivation for food, protection, and structural purposes. We consider there is much to learn from these symbioses, in special from the community-level degradation of recalcitrant biomass and defensive metabolites. Microbial plant-degrading systems at the core of insect fungicultures could be promising candidates for degrading synthetic plastics. Here, we first compare the degradation of lignocellulose and plastic polymers, with emphasis in the overlapping microbial players and enzymatic activities between these processes. Second, we review the literature on diverse insect fungiculture systems, focusing on features that, while supporting insects' ecology and evolution, could also be applied in biotechnological processes. Third, taking lessons from these microbial communities, we suggest multidisciplinary strategies to identify microbial degraders, degrading enzymes and pathways, as well as microbial interactions and interdependencies. Spanning from multiomics to spectroscopy, microscopy, stable isotopes probing, enrichment microcosmos, and synthetic communities, these strategies would allow for a systemic understanding of the fungiculture ecology, driving to application possibilities. Detailing how the metabolic landscape is entangled to achieve ecological success could inspire sustainable efforts for mitigating the current environmental crisis.

Characteristics of Initial Attachment and Biofilm Formation of Pseudomonas aeruginosa on Microplastic Surfaces

The toxic effect of microplastics on living organisms is emerging as a serious environmental issue nowadays. The biofilm formed on their surface by microorganisms can further increase the toxicity, but the mechanism of biofilm formation on microplastics is not yet fully understood because of the complexities of other factors. This study aimed to identify the factors with an important influence on biofilm formation on microplastic surfaces. The microtiter plate assay was used to evaluate the biofilms formed by Pseudomonas aeruginosa PAO1, a model microorganism, on four types of microplastics, including polyethylene, polystyrene, polypropylene, and polytetrafluoroethylene. The density of microplastics was found to be a key factor in determining the amount of biofilm formation because the density relative to water has a decisive effect on the behavior of microplastics. Biofilm formation on plastics with densities similar to that of water showed remarkable differences based on surface characteristics, whereas biofilm formation on plastics with a higher density was significantly influenced by particle movement in the experimental environment. Furthermore, biofilm formation was inhibited by adding a quorum quenching enzyme, suggesting that QS is critical in biofilm formation on microplastics. This study provides useful information on biofilm formation on microplastic surfaces.

Short-term exposure to soils and sludge induce changes to plastic morphology and 13C stable isotopic composition

There is concern about the buildup of plastic waste in soil, their degradation into microplastics, and their potential to interfere with the natural processing of soil organic carbon and other nutrient cycling processes. Here we used scanning electron microscopy (SEM) and ¹³C isotope ratio mass spectrometry to determine if precut consumer plastics comprised of either high density polyethylene (HDPE), a blend of linear low density polyethylene and low density polyethylene (L/LDPE), or polyethylene terephthalate (PETE) would degrade or transform during a short-term, 32 day, exposure to soil or sludge in laboratory microcosms. SEM confirmed morphological changes occurred to all plastics, but the attachment of biofilm and presence of microorganisms mostly favored PETE and HDPE surfaces. These observations support the idea that abiotic and/or biotic processes may degrade plastics in soil; however distinguishable and significant changes in mean stable isotopic values (Δδ¹³C) of ~0.2-0.7‰ were only observed for exposed PETE and HDPE. This indicates that each plastic's degradation in soil may be dependent on their physical and chemical properties, with L/LDPE being more resistant and less prone to degradation compared to the others, and less dependent on the environmental conditions or properties of the soil or sludge. Our experiments were short-term and while the mechanisms of degradation are not clear, the results provide strong motivation for further studies of plastic fate and processing in soil systems. Direct mechanistic studies using stable isotopic approaches in combination with other characterizations and techniques are clearly warranted and may lead to a significant enhancement in our present understanding of the interactions and dynamics of plastics in the soil environment.

Soil plastisphere: Exploration methods, influencing factors, and ecological insights

Microplastic (MP), an emerging contaminant, is globally prevalent and poses potential environmental threats and ecological risks to both aquatic and terrestrial ecosystems. When MPs enter into natural environments, they may serve as artificial substrates for microbial colonization and plastisphere formation, providing new ecological niches for microorganisms. Recent studies of the plastisphere have focused on aquatic ecosystems. However, our understanding of the soil plastisphere e.g. its formation process, microbial ecology, co-transport of organic pollutants and heavy metals, and effects on biogeochemical processes is still very limited. This review summarizes latest methods used to explore the soil plastisphere, assesses the factors influencing the microbial ecology of the soil plastisphere, and sheds light on potential ecological risks caused by the soil plastisphere. The formation and succession of soil plastisphere communities can be driven by MP characteristics and soil environmental factors. The soil plastisphere may affect a series of ecological processes, especially the co-transport of environmental contaminants, biodegradation of MPs, and soil carbon cycling. We aim to narrow the knowledge gap between the soil and aquatic plastisphere, and provide valuable guidance for future research on the soil plastisphere in MP-contaminated soils.

Effect of LDPE and biodegradable PBAT primary microplastics on bacterial community after four months of soil incubation

Biodegradable plastics would be gradually degraded by microbes after being used and discarded, forming biodegradable microplastics (BMPs). It is however not clear if it, like conventional microplastics, can affect the original soil ecological balance. In this study, the non-degradable LDPE (low density polyethylene) was used as the reference primary microplastic, and the BMP PBAT (polyadipate/butylene terephthalate) was used as the test object. The effects of the amount of PBAT on soil physical-chemical properties, bacterial community were investigated using high throughput sequencing. The results showed that when the highest amount of PBAT applied was up to 250 times higher than the normal application amount, resulted in a certain dose-effect, and a higher amount of PBAT would reduce the content of NO₃^--N and TP. The lower amount of PBAT relatively increased the diversity of soil bacterial communities, and the relative abundance of the unique Azotobacter increased with increasing PBAT amount. The abundance of bacterial community in soil with different PBAT amounts was significantly correlated with the soil's physical-chemical properties. In addition, Mesorhizobium, TM7a and Azotobacter were observed to be highly tolerant bacteria in PBAT containing soil which can be actively explored to study the biodegradation of BMPs PBAT.

Activities of Microplastics (MPs) in Agricultural Soil: A Review of MPs Pollution from the Perspective of Agricultural Ecosystems

Microplastics are emerging persistent pollutants which have attracted increasing attention worldwide. Although microplastics have been widely detected in aquatic environments, their presence in soil ecosystems remains largely unexplored. Plastic debris accumulates in farmland, causing serious environmental problems, which may directly affect food substances or indirectly affect the members in each trophic level of the food chain. This review summarizes the origins, migration, and fate of microplastics in agricultural soils and discusses the interaction between microplastics and the components in farmland from the perspectives of toxicology and accumulation and deduces impacts on ecosystems by linking the organismal response to an ecological role. The effects on farmland ecosystem function are also discussed, emphasizing the supply of agricultural products, food chain pathways, carbon deposition, and nitrogen cycling and soil and water conservation, as microplastic pollution will affect agricultural ecosystems for a long period, posing an ecological risk. Finally, several directions for future research are proposed, which is important for reducing the effect of microplastics in agricultural systems.

Rogue one: A plastic story

Plastic comprises of variety of polymers and has many applications, but the waste generated by plastic pose threat to environment and marine life. Plastic can be classified into two types: thermoplastics and thermosetting and are divided into 7 different categories: (Polyethylene Terephthalate [PETE], High-Density Polyethylene [HDPE], Polyvinyl Chloride [PVC], Low-Density Polyethylene [LDPE], Polypropylene [PP], Polystyrene or Styrofoam [PS] & Polycarbonate or ABS [others]). To curb the deleterious effects of plastic waste various methods have been devised and utilized that include chemical, physical and biological treatments. One of the aspects primarily focused by the researchers is the phenomenon of biodegradation and there are many microorganisms (bacteria) that have the ability to carry out this particular process. These bacteria assist biodegradation by production of several enzymes like PETases and MHETases. There are few microorganisms that have been listed which cannot be applied for industrial use due to its low biodegradation capacity. To overcome this problem, PHA is one of the alternatives to replace the synthetic plastic due to its high degrading capacity.

To Waste or Not to Waste: Questioning Potential Health Risks of Micro- and Nanoplastics with a Focus on Their Ingestion and Potential Carcinogenicity

Micro- and nanoplastics (MNPs) are recognized as emerging contaminants, especially in food, with unknown health significance. MNPs passing through the gastrointestinal tract have been brought in context with disruption of the gut microbiome. Several molecular mechanisms have been described to facilitate tissue uptake of MNPs, which then are involved in local inflammatory and immune responses. Furthermore, MNPs can act as potential transporters ("vectors") of contaminants and as chemosensitizers for toxic substances ("Trojan Horse effect"). In this review, we summarize current multidisciplinary knowledge of ingested MNPs and their potential adverse health effects. We discuss new insights into analytical and molecular modeling tools to help us better understand the local deposition and uptake of MNPs that might drive carcinogenic signaling. We present bioethical insights to basically re-consider the "culture of consumerism." Finally, we map out prominent research questions in accordance with the Sustainable Development Goals of the United Nations.

Microplastics in marine and aquatic habitats: sources, impact, and sustainable remediation approaches

Plastic trash dumped into water bodies degrade over time into small fragments. These plastic fragments, which come under the category of micro-plastics (MPs), are generally 0.05-5 mm in size, and due to their small size they are frequently consumed by aquatic organisms. As a result, widespread MPs infiltration is a global concern for the aquatic environment, posing a threat to existing life forms. MPs easily bind to other toxic chemicals or metals, acting as vector for such toxic substances and introducing them into life forms. Polyethylene, polypropylene, polystyrene, and other polymers are emerging pollutants that are detrimental to all types of organisms. The main route for MPs into the aquatic ecosystems is through the flushing of urban wastewater. The current paper investigates the origin, environmental fate, and toxicity of MPs, shedding light on their sustainable remediation.

Graphical abstract

Unraveling the plastic degradation potentials of the plastisphere-associated marine bacterial consortium as a key player for the low-density polyethylene degradation

The omnipresent accumulation and non-degradable nature of plastics in the environment are posing an ever-increasing ecological threat. In this study, a total of 97 bacteria were isolated from macroplastic debris collected from the coastal environments of Andaman Island. The isolates were screened for LDPE degradation potential and were identified based on phenotypic, biochemical, and molecular characterization. 16S rDNA-based identification revealed that three-three isolates of each belong to the genus Oceanimonas and Vibrio, two were closely related to the genus Paenibacillus whereas, one-one was associated with the genus Shewanella, Rheinheimera, and Bacillus, respectively. A bacterial consortium was formulated using the top four isolates based on their individual LDPE degradation potentials. A significant increase (p < 0.05) in the mean LDPE degradation (47.07 ± 6.67% weight-loss) and change in thickness was observed after 120 days of incubation. FTIR spectrum, ¹³C NMR, and TG-DSC analyses demonstrated changes in the LDPE sheets' functional groups, crystallinity, and in thermal properties after 120 days of incubation. The SEM and AFM images confirmed bacterial attachments, an increase in surface roughness and deformities on LDPE sheets. This study reports a bacterial consortium that can efficiently degrade the plastics and can be used in providing eco-friendly mitigation of plastic waste.

Exploring the role of microbial biofilm for industrial effluents treatment

Biofilm formation on biotic or abiotic surfaces is caused by microbial cells of a single or heterogeneous species. Biofilm protects microbes from stressful environmental conditions, toxic action of chemicals, and antimicrobial substances. Quorum sensing (QS) is the generation of autoinducers (AIs) by bacteria in a biofilm to communicate with one other. QS is responsible for the growth of biofilm, synthesis of exopolysaccharides (EPS), and bioremediation of environmental pollutants. EPS is used for wastewater treatment due to its three-dimensional matrix which is composed of proteins, polysaccharides, humic-like substances, and nucleic acids. Autoinducers mediate significantly the degradation of environmental pollutants. Acyl-homoserine lactone (AHL) producing bacteria as well as quorum quenching enzyme or bacteria can effectively improve the performance of wastewater treatment. Biofilms-based reactors due to their economic and ecofriendly nature are used for the treatment of industrial wastewaters. Electrodes coated with electro-active biofilm (EAB) which are obtained from sewage sludge, activated sludge, or industrial and domestic effluents are getting popularity in bioremediation. Microbial fuel cells are involved in wastewater treatment and production of energy from wastewater. Synthetic biological systems such as genome editing by CRISPR-Cas can be used for the advanced bioremediation process through modification of metabolic pathways in quorum sensing within microbial communities. This narrative review discusses the impacts of QS regulatory approaches on biofilm formation, extracellular polymeric substance synthesis, and role of microbial community in bioremediation of pollutants from industrial effluents.