Co-existence of polyethylene microplastics and tetracycline on soil microbial community and ARGs

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.

Antagonistic effects of polystyrene microplastics and tetracycline on Chlorella pyrenoidosa as revealed by infrared spectroscopy coupled with multivariate analysis

Microplastics and antibiotics are typical emerging contaminants in the environment, posing considerable risks to the ecosystem and human health. Previous studies have reported synergistic or antagonistic effects in the presence of both microplastics and antibiotics, destructing cell membrane, inhibiting photosynthetic capability, and inducing antioxidant enzyme activity. However, there is still lack of comprehensive understanding of the mechanisms. This study applied infrared biospectroscopy and multivariate analysis to explore the physiological and biochemical toxicity of polystyrene microplastics and tetracycline co-exposure on Chlorella pyrenoidosa. Either tetracycline or polystyrene microplastics alone posed toxicities on C. pyrenoidosa, mainly due to changes in photosynthetic content, cell membrane permeability, MDA content and antioxidant enzyme activity. Co-exposure of tetracycline and polystyrene microplastics exhibited an antagonistic effect. Infrared spectroscopy coupled with multivariate analysis isolated the discriminating biomarkers representing different toxicity mechanisms, successfully explaining the mechanism of antagonism as reducing ROS production, regulating antioxidant enzyme activity, stabilizing cell membrane, and interfering with signaling and protein synthesis. A random forest model was developed and satisfactorily recognized the toxicity of individual toxins (accuracy of 98.75 %, sensitivity of 99.22 % and specificity of 99.65 %). It also rapidly apportioned toxicity origin and evidenced that tetracycline contributed to the majority of binary toxicities. This study provided scientific guidance and a theoretical basis for assessing and apportioning the binary toxicities of emerging contaminants.

Effects of nitrogen-driven eutrophication on the horizontal transfer of extracellular antibiotic resistance genes in water-sediment environments

Excessive nitrogen and other nutrients can trigger the eutrophication of freshwater bodies. Antibiotic resistance genes (ARGs) are now recognized as environmental pollutants, with extracellular ARGs (eARGs) being the dominant form in sediments. However, research on the propagation characteristics of eARGs remains limited. This study investigated the transfer characteristics of kanamycin resistance (KR) genes in the pEASY-T1 plasmid to intracellular DNA (iDNA) and extracellular DNA (eDNA) in water and sediment microenvironments under increasing nitrogen concentrations, as well as the community structure of free-living (FL) and particle-attached (PA) bacteria. The results revealed KR genes relative abundance in free extracellular DNA (f-eDNA) and adsorbed extracellular DNA (a-eDNA) of the water initially decreased and then increased with rising nitrogen concentrations. Its abundance in iDNA of the sediments decreased significantly with increasing nitrogen content, with relative abundance ranging from 5.09 × 10-4 to 1.14 × 10-3 copies/16SrRNA. The transfer from eDNA to iDNA in the water showed a rising and then falling trend as nitrogen concentration rose. The transfer of iDNA from the water to iDNA in sediments exhibited the opposite pattern. Additionally, copper (Cu) and zinc (Zn) were identified as key factors influencing the abundance of KR genes in the water, but total phosphorus (TP) was the primary determinant of KR gene distribution in sediments according to random forest analysis. These findings reveal novel mechanisms of eARG propagation in eutrophic environments, providing a theoretical foundation for managing antibiotic resistance in aquatic ecosystems.

Toxic effects of tetracycline on non-target lichen Evernia prunastri

Tetracycline (TC) antibiotics are one of the class of drugs widely used in clinical practice but also constitute a significant environmental concern. However, the adverse effects of TC on non-target organisms have not been well studied. The aim of this study was to examine the influence of exposure to high levels of TC on thalli of lichens to determine the impact on (1) physiological parameters including integrity of cell membranes, photosynthetic efficiency and viability, (2) oxidative stress response such as membrane lipid peroxidation, and (3) enzymatic antioxidant activities as catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR). Data demonstrated that exposure to tetracycline did not markedly affect the lichen membrane damage as indicated by no change in conductivity. This antibiotic diminished the potential photosystem II efficiency (FV/FM) indicating enhanced susceptibility as evidenced by lower chlorophyll fluorescence and chlorophyll content. The viability of lichens exposed to high concentrations of tetracycline was significantly reduced. The concentrations of thiobarbituric acid reactive substances were markedly elevated with increasing concentrations of antibiotics. At higher TC concentrations, 500 mg/L SOD activity was significantly elevated. In the case of CAT, APX and GR, TC at higher concentrations significantly decreased these enzymic activities. The findings of this study contribute to the knowledge that TC antibiotics exert adverse ecotoxicological effects on lichens at high concentrations and provided a better understanding of the mechanisms underlying toxicity. Data also indicates that lichens may serve as an effective biomonitoring species for TC antibiotic exposure.

Metagenomics reveals combined effects of microplastics and antibiotics on microbial community structure and function in coastal sediments

Microplastics and antibiotics are emerging pollutants in marine environments, yet their combined effects on coastal sediments remain poorly understood. This study examined the impacts of microplastics and antibiotics on sediment properties and microbial communities through a 60-day laboratory simulation. Results showed that microplastics significantly reduced carbon, nitrogen, and phosphorus levels in sediments, while both antibiotics and combined pollution decreased phosphorus content. Combined pollution also increased NH4+-N concentration. Enzyme activity analysis revealed that microplastics elevated alkaline phosphatase activity, antibiotics increased fluorescein diacetate (FDA) hydrolase activity but decreased urease activity, and their combination further enhanced FDA hydrolase activity. Metagenomics analysis demonstrated that the presence of microplastics and antibiotics altered microbial community structure and metabolic functions. The dominant phylum Pseudomonadota (42.62 %-56.24 %) showed reduced abundance under combined pollution. Antibiotics significantly increased resistance gene abundance, while combined pollution led to selective enrichment of these genes. Both pollutants inhibited ammonia assimilation, and antibiotics also suppressed dissimilatory nitrate reduction. Conversely, combined pollution promoted nitrification and nitrogen fixation. While microplastics and antibiotics inhibited methane synthesis, combined pollution increased methane production via elevated mttB and hdrA genes. Antibiotics also reduced methane-oxidizing bacteria and genes, suppressing methane oxidation. These findings provide crucial insights into the ecological impacts of microplastics and antibiotics on coastal sediments, offering a theoretical basis for future marine pollution management strategies.

Microplastics reduced the natural attenuation of antibiotic resistance genes in fertilized soils

The prolonged application of mulch and manure in agriculture has led to significant microplastic (MP) pollution in fertilized soils, raising global concerns about its potential impacts on soil health and ecosystem function. However, the effects of MP exposure on antibiotic resistance genes (ARGs) and microbial communities in fertilized soils are unknown. Therefore, we comprehensively explored the trends and drivers of ARGs during their natural abatement under the stress of conventional and biodegradable MP addition in fertilized soils using a soil microcosm experiment and metagenomic. The findings indicated that the presence of polybutylene succinate MPs (PBS-MPs) reduced the natural attenuation rate of ARGs in fertilized soils while increasing the fraction of high-risk ARGs in soils. Microbial communities and mobile genetic elements (MGEs) mainly drove the inhibitory effect of MPs on ARG abatement. Interestingly, most potential hosts for the coexistence of ARGs, metal resistance genes (MRGs), and MGEs were annotated as pathogens, such as Escherichia spp., Salmonella spp., and Klebsiella spp. In addition, MP stress in fertilized soil may lead to long-term contamination by highly virulent and antibiotic-resistant Escherichia coli. MPs influence the distribution of carbon sources, which in turn reduces the diversity and stability of soil microbial communities, while simultaneously promoting the colonization of crucial ARG hosts, like Dyella spp. This ultimately prolonged the high-risk state for ARG proliferation in the soil. This study highlights the significant risk posed by MPs to the persistence and spread of ARGs in fertilized soils. These results provide valuable insights for managing MP contamination in agricultural systems, emphasizing the need for sustainable practices to mitigate the long-term environmental risks associated with MP pollution.

Unraveling the Impact of Microplastic-Tetracycline Composite Pollution on the Moon Jellyfish Aurelia aurita: Insights from Its Microbiome

Microplastics have emerged as a pervasive marine contaminant, with extreme concentrations reported in deep-sea sediments (e.g., 1.9 million particles/m2) and localized accumulations near Antarctic research stations. Particular concern has been raised regarding their synergistic effects with co-occurring antibiotics, which may potentiate toxicity and facilitate antibiotic resistance gene dissemination through microbial colonization of plastic surfaces. To investigate these interactions, a 185-day controlled exposure experiment was conducted using Aurelia aurita polyps. Factorial combinations of microplastics (0, 0.1, 1 mg/L) and tetracycline (0, 0.5, 5 mg/L) were employed to simulate environmentally relevant pollution scenarios. Microbiome alterations were characterized using metagenomic approaches. Analysis revealed that while alpha and beta diversity measures remained unaffected at environmental concentrations, significant shifts occurred in the relative abundance of dominant bacterial taxa, including Pseudomonadota, Actinomycetota, and Mycoplasmatota. Metabolic pathway analysis demonstrated perturbations in key functional categories including cellular processes and environmental signal transduction. Furthermore, microplastic exposure was associated with modifications in polyp life-stage characteristics, suggesting potential implications for benthic-pelagic population dynamics. These findings provide evidence for the impacts of microplastic-antibiotic interactions on cnidarian holobionts, with ramifications for predicting jellyfish population responses in contaminated ecosystems.

Changes in electron distribution of aged microplastic and their environmental impacts in aquatic environments

Microplastics (MPs) are widespread environmental pollutants. This study primarily examines the changes in electro distribution of aged MPs in aquatic environments and their subsequent impact on the environment. Under the action of natural and artificial aging, the electron cloud arrangement of MPs will change, thus affecting the relevant properties of MPs. Among them, the free radicals formed by advanced oxidation technology will be enriched on the surface of MPs carrying benzene rings, and react with other pollutants (organic pollutants, heavy metals, etc.) adsorbed by MPs to form environmental persistent free radicals (EPFRs). The electron cloud density of MPs carrying EPFRs increases, and the reactivity will also increase. Additionally, the oxygen-containing functional groups on the surface of aged MPs enhance their selective adsorption, altering their environmental impact. MPs can serve as a source of free radicals in the environment, enhance the oxidation capacity of other substances in the environment, and even affect the expression of antibiotic resistance genes. In addition, MPs have a high mobility, which will have a greater negative impact in the environment. Additionally, the high mobility of MPs amplifies their negative environmental impact. This study examines the changes in electron distribution of aged MPs and highlights their effects on aquatic ecosystems, providing insights into pollution control, toxicity, and degradation mechanisms.

Vermicomposting significantly reduced antibiotic resistance genes in cow manure even under high tetracycline concentrations

Minimizing antibiotic resistance genes (ARGs) in livestock manure is crucial for curbing ARG dissemination. Vermicomposting can eliminate ARGs, but the effect of residual antibiotics on its reduction efficacy remains unclear. Herein, Eisenia foetida was employed to convert cow manure with varying concentrations of tetracycline (i.e., 0, 10, 100 mg/kg), aiming to explore the impact of tetracycline on ARG fate during vermicomposting for 35 days. Results showed that the total ARG abundance in vermicomposting (0.05 copies/16S rRNA copies) was significantly lower than that in natural composting (0.06 copies/16S rRNA copies) (p < 0.05). Notably, exposure to tetracycline increased total ARG abundance (p < 0.05) and stimulated microbial succession during vermicomposting, with some ARGs increasing and others decreasing. But ARGs removal in vermicomposting was still higher even under tetracycline stress than that in natural composting. Overall, vermicomposting is an effective method for reducing ARGs in cow manure even at high tetracycline levels.

The key role of magnetic iron-to-biochar mass ratios in the dissipation of oxytetracycline and its resistance genes in soils with and without biodegradable microplastics

There are challenges involved in the synergistic dissipation of antibiotics and antibiotic resistance genes (ARGs) in soil because ARGs are affected by not only the selective pressure of antibiotics but also microbial community succession and co-existing pollutants. Here, magnetic biochars (MBCs) at various magnetic iron-to-biochar mass ratios (3:1, 2:1, 1:1, 1:2, 1:3, 1:5, and 1:7) were synthesized to develop a strategy for the synergistic dissipation of oxytetracycline (OTC) and its resistance gene (tet) in soils with and without polybutylene adipate terephthalate (PBAT) microplastics (MPs). The results showed that MBC12 (1:2) achieved the greatest dissipation efficiencies of OTC in soils without and with PBAT MPs (95.27% and 94.50%, respectively). The reductive degradation of OTC via promoting the electron transfer during conversion between Fe(III) and Fe(II) overwhelmed biodegradation of OTC. MBCs effectively hindered the spread of tet in soil without PBAT MPs, with the efficiencies more than 60%; but they had little influence on its spread in soil with PBAT MPs, excluding MBC15 (1:5). The absolute abundance of tet, regardless of PBAT MPs, just significantly positively correlated with Serratia (the added exogenous tet-host bacterium), indicating that MBCs inhibited the horizontal transfer of tet at the inter-genus level. Down-regulating the degradation/utilization/assimilation metabolic function by MBCs (excluding MBC31, 3:1) contributed to the hindering class 1 integron gene (intI1)-driven tet propagation. After considering efficiency, cost and toxic effects, MBC12 (1:2) was recommended to use for synergistic dissipation of OTC and tet in soils without and with PBAT MPs.

Antibiotic sorption onto MPs in terrestrial environment: a critical review of the transport, bioaccumulation, ecotoxicological effects and prospects

Microplastics (MPs) and antibiotics are prevalent contaminants in terrestrial environment. MPs possess the ability to absorb antibiotics, resulting in the formation of complex pollutants. While the accumulation and fate of MPs and antibiotics in marine ecosystems have been extensively studied, their combined pollution behavior in terrestrial environments remains relatively underexplored. This paper describes the sources, migration, and compound pollution of MPs and antibiotics in soil. It reviews the mechanisms of compound toxicity associated with antibiotics and MPs, combining different biological classifications. Moreover, we highlight the factors that influence the effects of MPs as vectors and the critical elements driving the spread of antibiotic resistance genes (ARGs). These information suggests the potential mitigation measures for MPs contamination from different perspectives to reduce the impact of ARGs-carrying MPs on human health, specifically through transmission via plants, microbes, or terrestrial vertebrates. Finally, we identify gaps in scientific knowledge regarding the interaction between MPs and antibiotics in soil environments, including the need for standardized research methods, multi-dimensional studies on complex ecological effects, and more comprehensive risk assessments of other pollutants on human health. In summary, this paper provides foundational information for assessing their combined toxicity, offers insights into the distribution of these emerging pollutants in soil, and contributes to a better understanding of the environmental impact of these contaminants.

Environmental Health and Safety Implications of the Interplay Between Microplastics and the Residing Biofilm

The increasing prevalence of microplastics in the environment has raised concerns about their potential environmental and health implications. Biofilms readily colonize microplastics upon their entry into the environment, altering their surface characteristics. While most studies have explored how biofilms influence the adsorption and transportation of other contaminants by microplastics, the reciprocal interplay between microplastics and biofilms and the resulting ecological risks remain understudied. This review comprehensively reviews the impact of microplastic properties on biofilm formation and composition, including the microbial community structure. We then explore the dynamic interactions between microplastics and biofilms, examining how biofilms alter the physicochemical properties, migration, and deposition of microplastics. Furthermore, we emphasize the potential of biofilm-colonized microplastics to influence the environmental fate of other pollutants. Lastly, we discuss how biofilm-microplastic interactions may modify the bioavailability, biotoxicity, and potential health implications of microplastics.

Mechanism of microplastics promoting sulfamethoxazole biodegradation in activated sludge as revealed by DNA-stable isotope probing

Microplastics (MPs) often coexist with sulfonamide antibiotics (SAs) in the activated sludge of wastewater treatment plants (WWTPs). Microbial degradation is a crucial pathway for SAs removal in the activated sludge, though its response to MPs still yet to be disclosed. Here, we combined DNA-stable isotope probing (DNA-SIP), PICRUSt and MENA techniques to explore the impact of MPs on the microbial biodegradation of sulfamethoxazole (SMX) in the activated sludge. DNA-SIP revealed 20 genera were responsible for the SMX degradation in the activated sludge, with 13 of these genera being firstly linked with sulfonamide biodegradation. The potential SMX-degrading bacteria showed complex synergistic interaction with the other microbes. Eight degradation pathways were constructed based on the nine identified SMX-related degradation genes. MPs addition enhanced the SMX biodegradation by altering the structure of degrading microbes, increasing their relative abundance and promoting the synergistic interactions between potential SMX-degrading bacteria and other microbes in activated sludge. Besides, genes related to abundant energy production and biofilm formation were involved in SMX degradation in the activated sludge with MPs. Our study reveals the MPs influence on SMX biodegradation in activated sludge, and disclose the potential underlying mechanisms, which will benefit the regulation on antibiotic removal in WWTPs.

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.

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.

Effects of microplastics on dissipation of oxytetracycline and its relevant resistance genes in soil without and with Serratia marcescens: Comparison between biodegradable and conventional microplastics

The biodegradable (polybutylene adipate terephthalate: PBAT) and conventional (polyethylene: PE) microplastics (MPs) at 0.5 %, 1 %, and 2 % dosages (w/w) were added into soils with and without Serratia marcescens ZY01 (ZY01, a tet-host strain) to understand their different effects on the dissipation of oxytetracycline (OTC) and tet. The results showed that the dosages of PBAT MP exhibited different inhibition degrees of OTC biodegradation in soils regardless of ZY01, while the dosages of PE MP did not change the enhancement degree of OTC biodegradation in soils without ZY01. These differences were due to the higher adsorption capacity of OTC on PBAT MP and the stronger toxicity of PBAT MP to microorganisms. Besides soil organic matter, pH and total phosphorus were important factors regulating specific tet-host bacteria in soils with MPs (e.g., the nitrogen-cycling bacteria Steroidobacter and Nitrospira) and MPs + ZY01 (e.g., the phosphorus-cycling bacteria Saccharimonadales and Haliangium), respectively. Regardless of ZY01, a stronger selective harboring of tet-host bacteria in PE MP treatments than PBAT MP treatments was observed at the MP dosage of 1 % (w/w), while the opposite trend was true at the MP dosages of 0.5 % and 2 % (w/w). Some specific genera belonging to Actinobacteriota strongly associated with the class 1 integron-integrase gene (intI1), playing a critical role in the horizontal gene transfer of tet in soils especially for the co-existence of MPs and ZY01. This study will be helpful for understanding on how biodegradable and conventional MPs as hotspots affect the environmental behavior of antibiotics and ARGs in soil.

Global perspective of ecological risk of plastic pollution on soil microbial communities

Introduction

The impacts of plastic pollution on soil ecosystems have emerged as a significant global environmental concern. The progress in understanding how plastic pollution affects soil microbial communities and ecological functions is essential for addressing this issue effectively.

Methods

A bibliometric analysis was conducted on the literature from the Web of Science Core Collection database to offer valuable insights into the dynamics and trends in this field.

Results

To date, the effects of plastic residues on soil enzymatic activities, microbial biomass, respiration rate, community diversity and functions have been examined, whereas the effects of plastic pollution on soil microbes are still controversial.

Discussion

To include a comprehensive examination of the combined effects of plastic residue properties (Type, element composition, size and age), soil properties (soil texture, pH) at environmentally relevant concentrations with various exposure durations under field conditions in future studies is crucial for a holistic understanding of the impact of plastic pollution on soil ecosystems. Risk assessment of plastic pollution, particularly for nanoplasctics, from the perspective of soil food web and ecosystem multifunctioning is also needed. By addressing critical knowledge gaps, scholars can play a pivotal role in developing strategies to mitigate the ecological risks posed by plastic pollution on soil microorganisms.

Investigating the impact of microplastics on triphenyl phosphate adsorption in soil: Insights into environmental factors and soil properties

Microplastics (MPs) pose significant environmental pollution problems owing to their diverse properties such as various shapes, sizes, compositions, surface features, and levels of degradation. Moreover, their interactions with toxic chemicals and aging processes add complexity to environmental research. This study investigated the adsorption of triphenyl phosphate (TPhP) in soil-only, MP-only, and soil-MP simulated environments under different conditions. The experiment involved three phases: initial exposure to a pH of 5.5 under fluorescent light, subsequent introduction of ultraviolet (UV) radiation, and pH adjustment to 4.0 and 7.0, while maintaining UV exposure, each lasting 7 days. The study found that environmental factors affected TPhP sorption capacity, with higher adsorption observed under UV radiation and acidic conditions. In contrast, the MP-only systems showed no clear trend for TPhP adsorption, suggesting kinetic limitations. When MPs were added to the soil, the adsorption dynamics were altered, with varying adsorption capacities observed for different MP polymers under different aging conditions. ATR-FTIR spectroscopy, micro-Raman spectroscopy, and water contact angle measurements suggested potential photooxidation processes and changes in the surface hydrophobicity of the MPs subjected to simulated environmental conditions. This study provides valuable insights into the interplay between soil properties, MP characteristics, and environmental factors in determining TPhP sorption dynamics in soil-MP environments.

Ecotoxicological Effects of Microplastics Combined With Antibiotics in the Aquatic Environment: Recent Developments and Prospects

Both microplastics and antibiotics are commonly found contaminants in aquatic ecosystems. Microplastics have the ability to absorb antibiotic pollutants in water, but the specific adsorption behavior and mechanism are not fully understood, particularly in relation to the impact of microplastics on toxicity in aquatic environments. We review the interaction, mechanism, and transport of microplastics and antibiotics in water environments, with a focus on the main physical characteristics and environmental factors affecting adsorption behavior in water. We also analyze the effects of microplastic carriers on antibiotic transport and long-distance transport in the water environment. The toxic effects of microplastics combined with antibiotics on aquatic organisms are systematically explained, as well as the effect of the adsorption behavior of microplastics on the spread of antibiotic resistance genes. Finally, the scientific knowledge gap and future research directions related to the interactions between microplastics and antibiotics in the water environment are summarized to provide basic information for preventing and treating environmental risks. Environ Toxicol Chem 2024;43:1950-1961. © 2024 SETAC.

Sensitive and selective detection of tetracycline using fluorescence-enhanced Eu(III)-functionalized silver nanoparticles with homocysteine

Utilizing metal luminescence enhancement to design fluorescent probes is a very sensible strategy. Herein, a fluorescent probe based on europium (III)-functionalized silver nanoparticles-conjugated homocysteine (AgNPs-Hcy-Eu3+) was proposed for the selective and sensitive detection of tetracycline (TC). In this probe, Eu(III) was employed as the detection signal unit for TC, while AgNPs-Hcy was used as the ligand of fluorescence enhancement. When TC exists, it can bind to Eu3+ immobilized in AgNPs-Hcy, leading to an enhanced fluorescence signal from Eu3+ through energy transfer. Under optimal conditions, the fluorescence intensity of AgNPs-Hcy-Eu3+ increased linearly with increasing TC concentration in the range of 0.1-30 μM (R2 = 0.9964). The fluorescent probe own fluorescence enhancement, paving the way for sensitive detection with a low detection limit of 0.083 μM. It also has good selectivity for common antibiotics and anions. This work can be applied to the determination of TC in tap water and milk with recoveries of 94-98.5%. We expect AgNPs-Hcy-Eu3+ to have potential applications in environmental testing and food safety.

Mixtures of Micro and Nanoplastics and Contaminants of Emerging Concern in Environment: What We Know about Their Toxicological Effects

In real environments, pollutants do not occur in isolation. Instead, they can be found in complex mixtures with effects that are completely different from those of the individual components. In this review, articles from 2017 to May 2024 have been selected to provide an overview of the existing knowledge on complex mixtures between micropollutants and micro and nanoplastics in organisms in terrestrial and aquatic environments. It was found that the corresponding toxicological parameters to determine the interaction between the compounds were not calculated in most of the literature reviewed. Our analysis shows that, in aquatic environments, synergistic effects have been found more frequently than antagonistic effects. In terrestrial environments, the joint toxicological action of microplastics or nanoplastics with emerging contaminants has been less studied, but synergistic effects may also predominate. Future work should thoroughly investigate the nature of the interactions in order to properly assess the risk posed by this cocktail of compounds in ecosystems.

Microplastic pollution promotes soil respiration: A global-scale meta-analysis

Microplastic (MP) pollution likely affects global soil carbon (C) dynamics, yet it remains uncertain how and to what extent MP influences soil respiration. Here, we report on a global meta-analysis to determine the effects of MP pollution on the soil microbiome and CO2 emission. We found that MP pollution significantly increased the contents of soil organic C (SOC) (21%) and dissolved organic C (DOC) (12%), the activity of fluorescein diacetate hydrolase (FDAse) (10%), and microbial biomass (17%), but led to a decrease in microbial diversity (3%). In particular, increases in soil C components and microbial biomass further promote CO2 emission (25%) from soil, but with a much higher effect of MPs on these emissions than on soil C components and microbial biomass. The effect could be attributed to the opposite effects of MPs on microbial biomass vs. diversity, as soil MP accumulation recruited some functionally important bacteria and provided additional C substrates for specific heterotrophic microorganisms, while inhibiting the growth of autotrophic taxa (e.g., Chloroflexi, Cyanobacteria). This study reveals that MP pollution can increase soil CO2 emission by causing shifts in the soil microbiome. These results underscore the potential importance of plastic pollution for terrestrial C fluxes, and thus climate feedbacks.

Ecological effect of microplastics on soil microbe-driven carbon circulation and greenhouse gas emission: A review

Soil organic carbon (SOC) pool, the largest part of terrestrial ecosystem, controls global terrestrial carbon balance and consequently presented carbon cycle-climate feedback in climate projections. Microplastics, (MPs, <5 mm) as common pollutants in soil ecosystems, have an obvious impact on soil-borne carbon circulation by affecting soil microbial processes, which play a central role in regulating SOC conversion. In this review, we initially presented the sources, properties and ecological risks of MPs in soil ecosystem, and then the differentiated effects of MPs on the component of SOC, including dissolved organic carbon, soil microbial biomass carbon and easily oxidized organic carbon varying with the types and concentrations of MPs, the soil types, etc. As research turns into a broader perspective, greenhouse gas emissions dominated by the mineralization of SOC coming into view since it can be significantly affected by MPs and is closely associated with soil microbial respiration. The pathways of MPs impacting soil microbes-driven carbon conversion include changing microbial community structure and composition, the functional enzyme's activity and the abundance and expression of functional genes. However, numerous uncertainties still exist regarding the microbial mechanisms in the deeper biochemical process. More comprehensive studies are necessary to explore the affected footprint and provide guidance for finding the evaluation criterion of MPs affecting climate change.

Effects of microplastics on soil microorganisms and microbial functions in nutrients and carbon cycling - A review

The harmful effects of microplastics (MPs) pollution in the soil ecosystem have drawn global attention in recent years. This paper critically reviews the effects of MPs on soil microbial diversity and functions in relation to nutrients and carbon cycling. Reports suggested that both plastisphere (MP-microbe consortium) and MP-contaminated soils had distinct and lower microbial diversity than that of non-contaminated soils. Alteration in soil physicochemical properties and microbial interactions within the plastisphere facilitated the enrichment of plastic-degrading microorganisms, including those involved in carbon (C) and nutrient cycling. MPs conferred a significant increase in the relative abundance of soil nitrogen (N)-fixing and phosphorus (P)-solubilizing bacteria, while decreased the abundance of soil nitrifiers and ammonia oxidisers. Depending on soil types, MPs increased bioavailable N and P contents and nitrous oxide emission in some instances. Furthermore, MPs regulated soil microbial functional activities owing to the combined toxicity of organic and inorganic contaminants derived from MPs and contaminants frequently encountered in the soil environment. However, a thorough understanding of the interactions among soil microorganisms, MPs and other contaminants still needs to develop. Since currently available reports are mostly based on short-term laboratory experiments, field investigations are needed to assess the long-term impact of MPs (at environmentally relevant concentration) on soil microorganisms and their functions under different soil types and agro-climatic conditions.

Contaminants of Emerging Concern: Antibiotics Research in Mussels from the Coasts of the Tyrrhenian Sea (Sardinia, Italy)

Contaminants of emerging concern (CECs) are compounds found in several environmental compartments whose ubiquitous presence can cause toxicity for the entire ecosystem. Several personal care products, including antibiotics, have entered this group of compounds, constituting a major global threat. It is essential to develop simple and reliable methods by which to quantify these contaminants in several matrices. In this work, mussels were chosen as sentinel organisms to assess environmental pollution and the safety of bivalve mollusk consumption according to the "One Health perspective". A liquid chromatographic tandem mass spectrometry method (LC-MS/MS) was developed for the quantification of two macrolides, erythromycin (ERY) and azithromycin (AZI), in mussels. This new method was validated according to international guidelines, showing high selectivity, good recoveries (>60% for both of them), sensitivity, and precision. The method was successfully applied for ERY and AZI research in mussels farmed along the Sardinian coasts (Italy), demonstrating itself to be useful for routine analysis by competent authorities. The tested macrolides were not determined in the analyzed sites at concentrations above the limits of detection (LODs). These results demonstrate the food safety of mussels (as concerns the studied antibiotics) and a negligible amount of pollution derived from these drugs in the studied area.

Effects of hexabromocyclododecane and polyethylene microplastics on soil bacterial communities

Hexabromocyclododecane (HBCD) and polyethylene (PE) microplastic are ubiquitous pollutants, and knowledge about the effects of HBCD and PE pollution on soil bacterial communities remains obscure. In this study, the effects of different HBCD and PE concentrations and combined HBCD and PE exposure on the diversity, composition, and function of agricultural soil bacterial communities over 4 months were systematically examined for the first time. Generally, soil bacterial communities were influenced in both the 1-month and 4-month scenarios through HBCD and PE separately as well as combined exposure. After 4 months of exposure, PE and combined exposure significantly affected soil bacterial alpha diversity, however, low concentration of HBCD showed no apparent influence. 1-month and 4-month HBCD, PE, and combined exposure significantly influenced bacterial beta diversity. Compared with 1 month of exposure, HBCD, PE, and combined exposure demonstrated remarkable influences on soil bacteria after 4 months of exposure, especially on Nitrospirae, Elusimicrobia, Rokubacteria at the phylum level, and on MND1, Ruminiclostridium, Lysobacter, Anaeromyxobacter, Alistipes, WCHB1 at the genus level. The bacterial function analysis indicated that amino acid metabolism, carbohydrate metabolism, and membrane transport were the three predominant enriched bacterial functions after 1-month and 4-month HBCD and PE exposure. This research provides a comprehensive grasp of the effects of HBCD and PE pollution on soil microbial communities, which could have a beneficial impact on future soil pollution control.