Environmental Microorganisms Research Articles

Research progress in isolation strategies and bioactive substances of microorganisms in extreme environments

Microbial resources are diverse and abundant, serving as a crucial source for the discovery of bioactive substances. However, as the research on microbial secondary metabolites deepens, discovering new microorganisms and novel bioactive secondary metabolites from conventional environments is becoming increasingly challenging. The microorganisms inhabiting extreme environments have unique physiological characteristics and can develop distinctive metabolic pathways, holding immense potential for producing chemically diverse and novel bioactive secondary metabolites. This article comprehensively overviews the recent advancements in the isolation strategies of microorganisms from extreme environments and the research progress in their bioactive substances, including antimicrobial, anticancer, and antioxidant compounds. This review aims to serve as a reference for the development and utilization and the related studies of the microbial resources in extreme environments.

A Systematic Review of the Effect of Polyphenols on Alterations of the Intestinal Microbiota and Shared Bacterial Profiles Between Metabolic Syndrome and Acne

Introduction: Microbiota, composed of micro-organisms like bacteria, viruses, and non-pathogenic fungi, plays a crucial role in digestion, vitamin production, and protection against dangerous microbes. Several factors, including age, diet, alcohol consumption, stress, environmental microorganisms, and therapies (particularly antibiotics), as well as birth and nursing, could modify the microbiota. Recent research has highlighted its alteration and involvement in a various disease, including metabolic syndrome and acne. This systematic review aimed to identify common biomarkers and microbiota alterations shared between metabolic syndrome and acne, and to explore how the potential prebiotic activities of polyphenols may promote intestinal eubiosis. Materials and methods: A comprehensive search in PubMed and EMBASE resulted in 4142 articles, from which nine studies were selected based on specific criteria after removing duplicates and reviewing abstracts and full texts. All studies correlated the microbiota alteration in both pathologies and the activity of polyphenols in metabolic syndrome. Results: This review suggests that acne may be influenced by some of the same microorganisms involved in metabolic syndrome. While the literature highlights the effectiveness of polyphenols in treating metabolic syndrome, no studies have yet demonstrated their specific impact on acne. Conclusions: The research points to the potential benefits of polyphenols in modulating the microbiota, which could be relevant for individuals with metabolic syndrome. However, due to the limited data available, it was not possible to establish a direct correlation between metabolic syndrome and acne.

Long-Term Autotrophic Growth and Solar-to-Chemical Conversion in Shewanella Oneidensis MR-1 through Light-Driven Electron Transfer.

Members of the genus Shewanella are known for their versatile electron accepting routes, which allow them to couple decomposition of organic matter to reduction of various terminal electron acceptors for heterotrophic growth in diverse environments. Here, we report autotrophic growth of Shewanella oneidensis MR-1 with photoelectrons provided by illuminated biogenic CdS nanoparticles. This hybrid system enables photosynthetic oscillatory acetate production from CO2 for over five months, far exceeding other inorganic-biological hybrid system that can only sustain for hours or days. Biochemical, electrochemical and transcriptomic analyses reveal that the efficient electron uptake of S. oneidensis MR-1 from illuminated CdS nanoparticles supplies sufficient energy to stimulate the previously overlooked reductive glycine pathway for CO2 fixation. The continuous solar-to-chemical conversion is achieved by photon induced electric recycling in sulfur species. Overall, our findings demonstrate that this mineral-assisted photosynthesis, as a widely existing and unique model of light energy conversion, could support the sustained photoautotrophic growth of non-photosynthetic microorganisms in nutrient-lean environments and mediate the reversal of coupled carbon and sulfur cycling, consequently resulting in previously unknown environmental effects. In addition, the hybrid system provides a sustainable and flexible platform to develop a variety of solar products for carbon neutrality.

The role of the AHR in host-pathogen interactions.

Host-microorganism encounters take place in many different ways and with different types of outcomes. Three major types of microorganisms need to be distinguished: (1) pathogens that cause harm to the host and must be controlled; (2) environmental microorganisms that can be ignored but must be controlled at higher abundance; and (3) symbiotic microbiota that require support by the host. Recent evidence indicates that the aryl hydrocarbon receptor (AHR) senses and initiates signalling and gene expression in response to a plethora of microorganisms and infectious conditions. It was originally identified as a receptor that binds xenobiotics. However, it was subsequently found to have a critical role in numerous biological processes, including immunity and inflammation and was recently classified as a pattern recognition receptor. Here we review the role of the AHR in host-pathogen interactions, focusing on AHR sensing of different microbial classes, the ligands involved, responses elicited and disease outcomes. Moreover, we explore the therapeutic potential of targeting the AHR in the context of infection.

The Microbiologically Influenced Corrosion and Protection of Pipelines: A Detailed Review

Microbial corrosion is the deterioration of materials associated with microorganisms in environments, especially in oil- and gas-dominated sectors. It has been widely reported to cause great losses to industrial facilities such as drainage systems, sewage structures, food-processing equipment, and oil and gas facilities. Generally, bacteria, viruses, and other microorganisms are the most important microorganisms associated with microbial corrosion. The destructive nature of these microorganisms differs based on the kind of bacteria involved in the corrosion mechanism. Amongst the microorganisms related to microbial corrosion, sulfate-reducing bacteria (SRB) is reported to be the most common harmful bacteria. The detailed mechanistic explanations relating to the corrosion of pipelines by sulfate-reducing bacteria are discussed. The mechanism of microbial corrosion in pipelines showing the formation of pitting corrosion and cathodic depolarization is also reported. The current review provides theoretical information for the control and protection of pipelines caused by microbial corrosion and how new eco-friendly protection methods could be explored.

Microbial Community Structure in the Taklimakan Desert: The Importance of Nutrient Levels in Medium and Culture Methods.

Although the Taklimakan Desert lacks the necessary nutrients and conditions to support an extensive ecosystem, it is a treasure trove of extremophile resources with special structures and functions. We analyzed the bacterial communities using oligotrophic medium and velvet cloth replicate combined with an extended culture duration. We isolated numerous uncultured microorganisms and rare microorganisms belonging to genera not often isolated or recently described, such as Aliihoeflea, Halodurantibacterium, and Indioceanicola. A total of 669 strains were isolated from the soil of the Taklimakan Desert, which were classified into 5 phyla, 7 classes, 25 orders, 42 families, 83 genera, and 379 species. Among them, 148 strains were potential new species. Our data show that even when working with samples from extreme environments, simple approaches are still useful for cultivating stubborn microbes. Through comparing the isolation effects of different nutrient levels on microbial diversity and abundance, the results show that reducing the nutrient level of the medium was more conducive to improving the culturability of microorganisms in low-nutrient environments, while the high-nutrient medium was more suitable for the isolation of dominant fast-growing strains. This study helps to better reflect the diversity of microbial resources and lays a foundation for the further research and utilization of soil microbial resources in the Taklimakan Desert.

Microplastics stress alters microorganism community structure and reduces the production of biogenic dimethylated sulfur compounds

AbstractDimethylsulfoniopropionate (DMSP) is a plentiful organic sulfur metabolite and the primary precursor for dimethyl sulfide (DMS), which plays a crucial role in global sulfur cycling, the formation of clouds, and cooling the warming earth. The origin and fate of DMSP are intricately linked to marine microorganisms, making the variation of the microorganism community crucial for DMSP dynamics. Nonetheless, the impact of pervasive marine microplastics on microorganisms and processes related to DMSP synthesis and degradation remains insufficiently investigated. To bridge this gap, a 14‐d deck‐based microcosm experiment was conducted, revealing that microplastics significantly altered the composition of microorganism communities and dramatically inhibited the release of DMS and DMSP. Furthermore, multivariate analysis demonstrated that the variations both in environmental variables and microorganism communities caused by microplastics were forcing factors in reducing DMS and DMSP release. In addition, the predicted function of the bacterial community showed a significant reduction in the presence of dddP and dmdA genes when exposed to microplastics, which directly disrupted both the demethylation and cleavage pathways of DMSP. These results indicate that the release of DMS and DMSP in marine ecosystems can be significantly affected by microplastics through influencing microorganisms. Thus, it is imperative to conduct research on controlling the synthesis and degradation of DMSP in the ocean, particularly in response to these environmental pollution issues. Such research can help discern new patterns from specific phenomena and identify crucial processes.

Myxococcus xanthus fruiting body morphology is important for spore recovery after exposure to environmental stress.

Environmental microorganisms have evolved a variety of strategies to survive fluctuations in environmental conditions, including the production of biofilms and differentiation into spores. Myxococcus xanthus are ubiquitous soil bacteria that produce starvation-induced multicellular fruiting bodies filled with environmentally resistant spores (a specialized biofilm). Isolated spores have been shown to be more resistant than vegetative cells to heat, ultraviolet radiation, and desiccation. The evolutionary advantage of producing spores inside fruiting bodies is not clear. Here, we examine a hypothesis that the fruiting body provides additional protection from environmental insults. We developed a high-throughput method to compare the recovery (outgrowth) of distinct cell types (vegetative cells, free spores, and spores within intact fruiting bodies) after exposure to ultraviolet radiation or desiccation. Our data indicate that haystack-shaped fruiting bodies protect spores from extended UV radiation but do not provide additional protection from desiccation. Perturbation of fruiting body morphology strongly impedes recovery from both UV exposure and desiccation. These results hint that the distinctive fruiting bodies produced by different myxobacterial species may have evolved to optimize their persistence in distinct ecological niches.IMPORTANCEEnvironmental microorganisms play an important role in the production of greenhouse gases that contribute to changing climate conditions. It is imperative to understand how changing climate conditions feedback to influence environmental microbial communities. The myxobacteria are environmentally ubiquitous social bacteria that influence the local microbial community composition. Defining how these bacteria are affected by environmental insults is a necessary component of predicting climatic feedback effects. When starved, myxobacteria produce multicellular fruiting bodies filled with spores. As spores are resistant to a variety of environmental insults, the evolutionary advantage of building a fruiting body is not clear. Using the model myxobacterium, Myxococcus xanthus, we demonstrate that the tall, haystack-shaped fruiting body morphology enables significantly more resistance to UV exposure than the free spores. In contrast, fruiting bodies are slightly detrimental to recovery from extended desiccation, an effect that is strongly exaggerated if fruiting body morphology is perturbed. These results suggest that the variety of fruiting body morphologies observed in the myxobacteria may dictate their relative resistance to changing climate conditions.

Response of earthworm enzyme activity and gut microbial functional diversity to carbendazim in the manured soil.

The effect of pesticide pollution on environmental microorganisms in soil has become the focus of widespread concern in society today. The response of earthworm gut and surrounding soil microbial functional diversity and enzyme activity to carbendazim (CBD) was studied in a soil-earthworm ecosystem amended with manure. In the experiment, CBD was added to the manured soil (MS). Meanwhile, the pesticide treatment without manure and the control treatment without pesticides were also set up. The activities of catalase (CAT) and acetylcholinesterase (AChE) were measured to evaluate the toxicity of CBD. The Biolog method was used to assess the functional diversity of the microbial community. In the 2 mg/kg CBD treatment, earthworm AChE activity decreased significantly in the MS after 14 d, which occurred earlier than in the un-manured soil (NS). The changes of earthworm CAT activity in the pesticide treatments showed a trend of initially increasing and then maintaining at a high activity level. However, the CAT activities at 28 d in the manured soils were clearly lower than that at 7 d for both the CBD treatments, while they remained stable in the control treatments. The carbon source utilization, Simpson index, Shannon index, and McIntosh index of soil microorganisms in the MS treatments were significantly higher than those in the NS treatments. The overall activity of earthworm gut microorganisms in the MS treated with 2 mg/kg CBD was higher than that in the control. Also, CBD treatment (2 mg/kg) increased significantly the Simpson index and McIntosh index of earthworm gut microorganisms. The results indicated that the enzyme activities in the manured soils increased before 7 d for the pesticide treatments. Furthermore, exposure to CBD at a high concentration in the MS not only led to the earlier inhibition of earthworm enzyme activity but also significantly improved the overall activity of earthworm gut microorganisms and microbial functional diversity. This study revealed the ecotoxicological effects of earthworms in response to pesticide stress following the use of organic fertilizers under facility environmental conditions, which can provide a theoretical basis for the remediation of pesticide pollution in soil in the future.

Photoelectron-promoted metabolism of sulphate-reducing microorganisms in substrate-depleted environments.

Sulphate-reducing microorganisms, or SRMs, are crucial to organic decomposition, the sulphur cycle, and the formation of pyrite. Despite their low energy-yielding metabolism and intense competition with other microorganisms, their ability to thrive in natural habitats often lacking sufficient substrates remains an enigma. This study delves into how Desulfovibrio desulfuricans G20, a representative SRM, utilizes photoelectrons from extracellular sphalerite (ZnS), a semiconducting mineral that often coexists with SRMs, for its metabolism and energy production. Batch experiments with sphalerite reveal that the initial rate and extent of sulphate reduction by G20 increased by 3.6 and 3.2 times respectively under light conditions compared to darkness, when lactate was not added. Analyses of microbial photoelectrochemical, transcriptomic, and metabolomic data suggest that in the absence of lactate, G20 extracts photoelectrons from extracellular sphalerite through cytochromes, nanowires, and electron shuttles. Genes encoding movement and biofilm formation are upregulated, suggesting that G20 might sense redox potential gradients and migrate towards sphalerite to acquire photoelectrons. This process enhances the intracellular electron transfer activity, sulphur metabolism, and ATP production of G20, which becomes dominant under conditions of carbon starvation and extends cell viability in such environments. This mechanism could be a vital strategy for SRMs to survive in energy-limited environments and contribute to sulphur cycling.

Prevalence of antibiotic resistance genes in different drinking water treatment processes in a northwest Chinese city.

Antibiotic resistance genes (ARGs) are an emerging issue which are receiving increasing concerns in drinking water safety. However, the factors (e.g. treatment processes and water quality) affecting the removal efficiency of ARGs in the drinking water treatment plants (DWTPs) is still unclear. This work investigated the ARG profiles in each treatment process of two DWTPs located in a northwest Chinese city. The results showed that tetracycline and sulfonamide resistance genes were predominant among the 14 targeted ARGs. After the treatment, the Z water treatment plant which demonstrated a higher removal rate of ARGs (ranging from 50 to 80%), compared to the S plant (50-75%). And the average removal rate of tetracycline resistance genes (tetA, tetG, tetQ, tetX) was about 49.18% (S plant) and 67.50% (Z plant), as well as the removal rate of 64.2% and 72.9% for sulfonamide resistance (sul1 and sul2) at S and Z water plants, respectively. It was found that the relative abundance of main microbial communities (such as Bacteroidota, Actinobacteria, Verrucomicrobiota, Roseomonas), α-diversity index, as well as the abundance of pathogenic bacteria were all significantly reduced after different treatment processes. Network co-occurrence analysis revealed that Methylocystis possibly was the potential host for most ARGs, and sul1 was found across a broad spectrum of microorganisms in the drinking water environment. Adonis analysis showed that heavy metals and microbial communities explain solely 44.1% and 35.7% of variances of ARGs within DWTPs. This study provides insights into the contamination status and removal efficiencies of ARGs in DWTPs, offering valuable references for future studies on ARG removal, propagation, and diffusion patterns in drinking water treatment.

Experimental and numerical study on upper-room Far-UVC system under different ventilation schemes to disinfect airborne microorganisms in indoor environments

Many deadly infectious diseases are transmitted through airborne routes in indoor environments. Far UV upper-room system combined with proper ventilation is regarded as an effective approach to disinfect airborne microorganisms. Despite the current advances in the far UV upper-room system, various types of data are still lacking to guide the efficient design and the safe operation. This study combines field air sampling, laboratory experiments and computational fluid dynamics simulations to advance the knowledge on the potential of far UV radiation for disinfection and its safety design. Our findings reveal that seven out of the eight measured room spaces are categorised as slightly polluted (1201–2000 CFU m−3) or polluted (>2000 CFU m−3). Proteobacteria and Firmicutes constitute 65.2 ± 10.6 % and 21.2 ± 5.68 % of the bacterial composition in congregate settings, respectively. Ultraviolet radiation proves effective in deactivating pathogenic microorganisms, characterized by a decay rate constant ranging from 0.0446 m2 J−1 to 0.464 m2 J−1, depending on the wavelength and the type of pathogenic microorganisms. The time response of Ultraviolet radiation is up to 12 min to achieve 92.1 % sterilisation. Despite the reduction in the sterilisation ratio of Ultraviolet radiation, maintaining a high ventilation rate is highly recommended to eliminate genetic material from pathogenic microorganisms. When the excimer lamp is installed higher than 1.9 m above the floor level, the radiation intensities at both standing and sitting height become lower than the safety threshold value of 0.166 W m−2. A combination of UV radiation at 222 nm and ventilation is effective for neutralising both gram-positive and -negative bacteria and can contribute to stop the spread of infectious diseases in congregate settings.

Exploring the microbiome: New horizons for emerging therapeutics

The document discusses the topic of microbiomes, specifically focusing on the human microbiome and its various aspects. It starts by explaining the concept of human microbiota, which refers to the collection of microorganisms that live in and interact with the human body. The document highlights the importance of these microbial ecosystems in maintaining overall health and wellbeing. The composition and function of the gut microbiome undergo significant changes during the first year of life, especially with the introduction of solid foods. The document discusses the different bacterial phyla that dominate the gut microbiome in neonatal infants and adults. It also mentions the role of the human gut microbiome in various health conditions such as liver diseases, diabetes, inflammatory bowel disease, autoimmune diseases, colon cancer, and central nervous system disorders. The document highlights the different sequencing techniques used in microbiome research, such as ITS sequencing, PCR amplicon-based sequencing, and shotgun metagenomic sequencing. It also discusses the concept of the halobiont and holo genome in relation to the microbiome. The document emphasizes the importance of studying the microbiome in the context of ecosystem health and discusses the impact of human populations on environmental microorganisms. Furthermore, the document covers the microbial barrier in the human gut, the role of the gut microbiota in various metabolic processes, and the application of gut microbiomes in bioengineering, both in humans and other organisms. Lastly, it discusses the importance of dietary interventions, prebiotics, and the role of various diets in influencing the composition of the gut microbiome and treating gastrointestinal disorders. Overall, the document provides a comprehensive overview of the human microbiome and its significance in health and disease, as well as its potential applications in bioengineering and dietary interventions.

From Mechanism-Based Retaining Glycosidase Inhibitors to Activity-Based Glycosidase Profiling.

Activity-based protein profiling (ABPP) is an effective technology for the identification and functional annotation of enzymes in complex biological samples. ABP designs are normally directed to an enzyme active site nucleophile, and within the field of Carbohydrate-Active Enzymes (CAZymes), ABPP has been most successful for those enzymes that feature such a residue: retaining glycosidases (GHs). Several mechanism-based covalent and irreversible retaining GH inhibitors have emerged over the past sixty years. ABP designs based on these inhibitor chemistries appeared since the turn of the millennium, and we contributed to the field by designing a suite of retaining GH ABPs modeled on the structure and mode of action of the natural product, cyclophellitol. These ABPs enable the study of both exo- and endo-acting retaining GHs in human health and disease, for instance in genetic metabolic disorders in which retaining GHs are deficient. They are also finding increasing use in the study of GHs in gut microbiota and environmental microorganisms, both in the context of drug (de)toxification in the gut and that of biomass polysaccharide processing for future sustainable energy and chemistries. This account comprises the authors' view on the history of mechanism-based retaining GH inhibitor design and discovery, on how these inhibitors served as blueprints for retaining GH ABP design, and on some current and future developments on how cyclophellitol-based ABPs may drive the discovery of retaining GHs and their inhibitors.

Temporal dynamics changes in the vaginal fluid microbiome: Implications for body fluid identification and estimating time since deposition (TsD) for forensics

Vaginal fluid analysis plays a crucial role in sexual assault investigations. However, vaginal fluid found at crime scenes is usually subject to a certain duration of exposure. This study thus aimed to assess the influence of different durations of exposure to indoor environment on the vaginal microbiota. The 16S rDNA high-throughput sequencing was used on vaginal fluid samples exposed for short-term (30 days) and long-term (240 days), respectively. Despite potential contamination from environmental microorganisms, particularly following long-term exposure, the results indicated that the vaginal microbiota after exposure was still dominated by Lactobacillus. Both in short-term and long-term exposure involving vaginal fluid, there were clusters with time-dependent characteristics, wherein the relative abundances of associated microbial genera showed a trend of increasing or decreasing over time. In addition, each bodily fluid presented with a unique array of dominant bacterial genera, enabling the differentiation of exposed vaginal fluid samples from other bodily fluids (semen, skin, saliva, feces) with a remarkable 98.75 % accuracy rate. Furthermore, the mean absolute error achieved by the long-term deposition time prediction model was 13.54 days. The mean absolute error for the short-term deposition time prediction model was notably lower, reaching just 2.05 days. In summary, this study investigates the variations in microbial communities within vaginal fluid subjected to different indoor exposure durations and explores their potential in body fluid identification and estimating the time since deposition, thereby contributing valuable supporting evidence in forensic investigations.

Intact-cell detection of halohydrin dehalogenase activity and preliminary assessment of marine adaptability

Halohydrin dehalogenase (HHDH) can degrade 1,2,3-trichloropropanol and other halogenated alcohols. These enzymes exhibit stereoselectivity and can be used to produce pure chiral epoxides and β-substituted alcohols of industrial value. The discovery of novel HHDHs from microorganisms in niche environments including the sea requires in-situ analysis of HHDH activity. Owing to its high practical value, HheC was selected as a target enzyme to establish an intact-cell method for detecting HHDH activity based on fluorescence spectroscopy. This approach relied on the principle that HHDH activity can change the pH in a system with weak buffering capacity, and that the fluorescence intensity of certain dyes is influenced by pH. The marine adaptability of the assay was subjected to preliminary investigation. The method is simple, rapid, and highly sensitive, as verified using gas chromatography-mass spectrometry. The detection limit of the method was OD600 (optical density at a 600 nm) of 0.025 for microorganisms containing HHDH which have activity comparable to that of HheC. With some improvements, this method holds potential for in-situ analysis and mining of marine microorganisms containing HHDH.

Primary succession of Bifidobacteria drives pathogen resistance in neonatal microbiota assembly

Human microbiota assembly commences at birth, seeded by both maternal and environmental microorganisms. Ecological theory postulates that primary colonizers dictate microbial community assembly outcomes, yet such microbial priority effects in the human gut remain underexplored. Here using longitudinal faecal metagenomics, we characterized neonatal microbiota assembly for a cohort of 1,288 neonates from the UK. We show that the pioneering neonatal gut microbiota can be stratified into one of three distinct community states, each dominated by a single microbial species and influenced by clinical and host factors, such as maternal age, ethnicity and parity. A community state dominated by Enterococcus faecalis displayed stochastic microbiota assembly with persistent high pathogen loads into infancy. In contrast, community states dominated by Bifidobacterium, specifically B. longum and particularly B. breve, exhibited a stable assembly trajectory and long-term pathogen colonization resistance, probably due to strain-specific functional adaptions to a breast milk-rich neonatal diet. Consistent with our human cohort observation, B. breve demonstrated priority effects and conferred pathogen colonization resistance in a germ-free mouse model. Our findings solidify the crucial role of Bifidobacteria as primary colonizers in shaping the microbiota assembly and functions in early life.

Using patterns of shared taxa to infer bacterial dispersal in human living environment in urban and rural areas.

Understanding how environmental microorganisms reach and interact with humans is a key question when aiming to increase human contacts with natural microbiota. Few methods are suitable for studying microbial dispersal at relatively large spatial scales. Thus, we tested an indirect method and studied patterns of bacterial taxa that are shared between humans and their living environment.

Effect of Treated Wastewater on the Distribution of Antyibiotic-Resistant Microorganisms in the Aquatic Environment

The effect of waste treatment plants in Pushchino, Russia on abundance of antibiotic-resistant microorganisms and determinants of multiple drug resistance in the Oka River water and sediments was investigated. Treated wastewater was found to contribute to contamination of the Oka surface water layer with aminoglycoside-resistant strains. The role of Pushchino waste treatment plants in the dissemination of multidrug-resistant strains and plasmids of the А/С incompatibility groups (IncA/C) was demonstrated. Waste treatment plants were shown to affect both the total abundance of eubacteria in sediments and to assect their composition, increasing the relative abundance of pseudomonads.

Migration and accumulation of microplastics in soil-plant systems mediated by symbiotic microorganisms and their ecological effects

The coexistence of microorganisms in complex soil environments greatly affects the environmental behavior and ecological effects of microplastics (MPs). However, relevant studies are sparse, and internal mechanisms remain unclear. Herein, arbuscular mycorrhizal fungi (AMF), a common symbiotic microorganism in the soil–plant system, was proved to significantly affect MPs absorption and migration with a “size effect”. Specifically, the existence of AMF accelerated small-sized MPs (0.5 μm) uptake but slowed large-sized MPs (2 μm) uptake in lettuce. The content of 0.5 μm MPs absorbed by plants with AMF was 1.26 times that of the non-AMF group, while the content of 2 μm MPs was only 77.62 % that of non-AMF group. Additionally, the different effects of microorganisms on the intake content of MPs with different particle sizes in plants also led to different toxic effects of MPs on lettuce, that is, AMF exacerbated small-size MPs toxicity in lettuce (e.g., reduced plant biomass, photosynthesis, etc), and it weakened large-sized MPs toxicity (e.g., increased plant height, antioxidant enzyme activity, etc). The above phenomenon mainly because of the change in AMF on the plant root structure, which can be visually observed through the intraradical and extraradical hyphae. The symbiotic structure (hyphae) formed by AMF and host plants root could enhance the absorption pathway for small-sized MPs in lettuce, although not for large-sized MPs. Additionally, the effects of AMF varied with the soil environment of differently sized MPs, which promoted the migration of small-particle MPs to plants but aggravated large-particle MPs fixation at the soil interface. These findings could deepen the understanding of MPs pollution in terrestrial systems and provide theoretical basis and technical support to accurately assess soil MPs pollution.