Polyethylene (PE) dominates global packaging waste, yet its fate remains poorly understood in dark, anoxic environments such as ocean sediments and landfills, which represent important reservoirs for discarded plastics. In this study, 800-day microcosm experiments were performed with PE samples retrieved from an active landfill site with distinct landfill durations. Results demonstrated that anaerobic microbes slowly degrade PE while enhancing the release of secondary pollutants, such as nanoplastics (NPs) and phthalate esters (PAEs). Microbial colonization increased the surface roughness of PE samples and the abundance of oxygenated functional groups, driving oxidative chain scission, NP release (2.4-4.3 × 1011 particles mL-1 leachate), and PAE biodegradation. Logarithmic curves derived from an improved Polymer Aging Index revealed a midage acceleration window, with PE buried for 7 years being the most susceptible to microbial attack. PE-associated microbial communities were dominated by deterministic assembly processes, with functional taxa being the dominant drivers of PE aging, and PAE degraders exhibiting dual-threshold dynamics. Together, this study identifies a coupled oxidation-biodegradation-fragmentation feedbacks mechanism that governs the fate of PE in landfills, highlighting the dual microbial role in degrading PE and amplifying associated pollutant release.

Antibiotic resistance genes (ARGs) represent a critical global public health threat. Effective resistome management within the One Health framework requires a comprehensive understanding of the sources and movement of ARGs across environmental media. This study provides a detailed analysis of resistome characteristics and dynamics in global landfill systems. Landfill systems were found to harbor diverse and highly mobile ARGs, with multidrug-resistant genes (MDRGs) comprising 32.63% of total ARGs, and comparable or even higher levels of associated ARG subtypes than in other environmental media, such as acidic mine wastewater. The ARG density on plasmids was 3.5 times higher than that on chromosomal sequences, with five times more abundant ARG-carrying plasmid-associated contigs in landfill systems than that in wastewater. At the metagenome-assembled genome level, members of the phylum Pseudomonadota were identified as the most abundant hosts (29.72%), harboring 47.74% and 56.47% of the total ARGs and MDRGs, respectively. Genomic analysis of 35 Pseudomonas spp. strains revealed unique Pseudomonas species in landfill systems, including P. aeruginosa . Resistome flow pathways were further mapped, including inflows into landfill (via soil, wastewater, freshwater, and the human and pig gut), movement within landfills (across landfill refuse, leachate, and airborne particles), and outflows from landfills (via landfill leachate effluent, gas emissions, and refuse evacuation). The results emphasized diverse resistome development and movement within landfill systems, ultimately contributing to the environmental spread of ARGs. Thus, our study highlights the urgent need for comprehensive policies and management strategies to mitigate resistome proliferation at every stage of municipal solid waste management.

Biodegradation is a promising and environmentally friendly strategy for plastic pollution management. Landfills decompose municipal solid waste, including almost 50% of global plastic debris and even some of the oldest synthetic plastics, fostering naturally selected plastic biodegradation. Herein, we present a global collection of plastic biocatalytic enzymes from landfills using metagenomics and machine learning. Metagenomic analysis identified 117 plastic-degrading genes, with 39 incorporated in 22 prokaryotic metagenome-assembled genomes (MAGs). A machine-learning approach predicted 978,107 candidate plastic-degrading genes, 712 of which were encoded respectively by 150 MAGs. Our results highlight landfills as reservoirs of diverse, naturally selected plastic-degrading microbes and enzymes, serving as references and/or models for biocatalysis engineering and in situ bioremediation of plastic pollution.

Understanding the dynamics of microbial community and metabolic pathways involved in methanogenesis during municipal solid waste (MSW) decomposition is crucial for effective methane (CH4) management in landfills. This study investigated bacterial and methanogenic community composition, methanogenic metabolism, and their dynamics across typical phases of MSW decomposition-anaerobic acid phase, accelerated methanogenic phase, and decelerated methanogenic phase. Parallel bioreactors (A and B) were analyzed using metagenomics and natural stable carbon isotope analyses. CH4 production kinetics for both reactors were accurately simulated by the Gompertz kinetic model (R2 ​> ​0.98), Capturing key MSW decomposition phases characterized by variations in CH4 production, pH, and volatile fatty acids (VFAs) concentrations. Concurrently, the methanogenic community transitioned from an initial dominance of acetoclastic methanogens Methanothrix in reactor A, and Methanothrix and Methanosarcina in reactor B to a co-dominance of hydrogenotrophic methanogens Methanobacterium and acetoclastic methanogens Methanothrix and Methanosarcina in both reactors. Acetate concentration and CH4 yield were identified as primary factors shaping methanogen community structure. Acetoclastic methanogenesis remained the predominant pathway, accounting for 66.5–85.9 ​% of total methanogenesis modules., This dominance was supported by stable carbon isotope (αc constantly below 1.055 in both reactors) and metagenomic analyses, particularly the prevalence of acetate-metabolizing genes such as acetate kinase and acetyl-CoA synthetase. Despite substantial variability in microbial community composition, acetoclastic methanogenesis consistently dominated CH4 production throughout MSW decomposition. These findings enhance understanding of methanogenesis in MSW landfills, supporting strategies to mitigate CH4 emissions and address climate goals.

Cadmium (Cd) accumulation in rice grains poses severe health risks. Conventional straw amendments exhibit inconsistent efficacy, likely because of variations in amendment types and soil sulfur deficiency. The pot experiment was evaluated in a Cd-contaminated paddy soil (3.18 mg Cd kg-1) to compare three treatments (1.0 % w/w) sources: WS (wheat straw), CW (wheat straw compost), and BW (wheat straw biochar) without or with sodium sulfate fertilization (30 mg sulfur kg-1). This experiment aimed to evaluate the Cd mobility, microbial diversity, and Cd accumulation in rice tissues. All treatments resulted in reduced Cd accumulation in brown rice at the maturity stage by 3 % (WS), 26 % (CW), and 60 % (BW), whereas sulfate co-application enhanced this reduction to 30 % (WS+S), 38 % (CW+S), and 66 % (BW+S). This could be attributed to decrease in soil Cd availability (17 %, 37 %, and 41 % for WS+S, CW+S, and BW+S, respectively, at the maturity stage), inhibition of Cd uptake by root iron plaque (-0.01 to -0.05), and decrease of Cd translocation in rice tissues (particularly phloem transfer). Microbial analysis revealed that biochar and compost preferentially increased bacterial alpha diversity and shifted microbial composition irrespective of sulfate supply, especially at the tillering and booting stages. Specifically, biochar and compost reduced Firmicutes (positively related to exchangeable Cd, P ≤ 0.01), and increased Bacteroidota and Proteobacteria (negatively related to exchangeable Cd, P ≤ 0.01) at these stages. These findings demonstrate that co-application of wheat straw biochar and sulfate offers a solution for remediating Cd-contaminated paddy soils while considering soil ecosystem health.

Biogenic gas in deep subsurface has gained significant attention as a clean and efficient energy source. Due to the challenges associated with sample extraction, knowledge regarding the methanogenesis mechanism in deep biogenic gas fields remains limited. Herein, metagenomic sequencing was employed to investigate the microbial communities, functional genes, metabolic pathways, and their potential determinants in rock samples collected from depths of 100, 1000, and 2000 meters within Quaternary biogenic gas fields in the Qaidam Basin. The analysis revealed substantial variation in the methanogenesis-associated microbiome across different depths. Key physicochemical parameters influencing microbial community composition and the relative abundance of methanogenesis-related functional genes included total carbon, carbon-to-nitrogen ratio, chlorine, boron, magnesium, and mineral composition. The dominant methanogens identified were Methanosarcina and Methanohalophilus, with their relative abundance correlating with the distribution of methane metabolism genes. Notably, only genes associated with acetate utilization methanogenic metabolic pathway were detected. Interestingly, significant increases in dolomite concentration at 1000 m and calcite at 2000 m were linked to variations in the abundance of methanogenesis-related functional genes, suggesting that lithological characteristics may serve as an indicator of methanogenic potential. Additionally, the study identified connections between carbon, nitrogen, and sulfur microbial cycling pathways and the abundance of methanogenesis-related functional genes, highlighting the auxiliary role of microbial-mediated carbon, nitrogen, and sulfur cycling in methanogenesis. These findings provide direct evidence of methanogenesis processes and their determinants, offering valuable insights into Quaternary biogenic gas production.

The ratio of soil dissolved organic carbon to nitrogen (DOC:N) influences mineralization and immobilization, consequently impacting soil nitrate nitrogen (NO3--N) accumulation and leaching. However, its relationship with soil NO3--N leaching remains ambiguous, especially in soil profiles. This study employed a soil column leaching experiment and a field investigation to elucidate the association between soil DOC:N ratios and potential leaching risk of NO3--N in fluvoaquic soil across three depths (0-20 cm, topsoil; 20-40 cm, subsoil; 40-60 cm, third-layer soil). Soil column demonstrated a positive linear correlation between both NO3--N concentration and the amount of leached NO3--N in soil leachate and soil NO3--N content extracted via cascade extraction methods. Within each soil layer, both parameters exhibited an exponential decrease with increasing soil DOC:N. Field validation confirmed robust negative exponential correlations between soil DOC:N and the corresponding NO3--N concentration in field soil solutions. High protease activity and high nitrogenase activity were respectively observed under low soil DOC:N ratio and high soil DOC:N ratio. Based on Groundwater Quality Standard (20 mg NO3--N L-1), critical DOC:N thresholds were established at 0.117 (topsoil), 0.145 (subsoil), and 0.137 (third-layer soil). The potential leaching risk of NO3--N was assessed by the DOC:N of soil collected from three depths in 2017. The potential risk for NO3--N leaching across all three layers showcased a consistent spatial distribution pattern: higher risks were identified around greenhouse land on the east bank of Chaobai River. These findings indicate that soil DOC:N can serve as an indicator for evaluating potential nitrate leaching risk.

Sulfur (S) is essential for rice growth and plays a pivotal role in soil pollution remediation. Wheat straw (W) amendment and sulfate (SO42-) fertilization are common agricultural practices in rice cultivation, yet their combined effects on S transformation, including organic sulfur (OS), available sulfate (AS), and reduced inorganic sulfur (RIS), in waterlogged paddy soils remain poorly understood. We conducted a 162-day incubation experiment with different W levels (0 %, 0.1 %, 0.5 %, and 1.0 %, w/w) and S rates (0 and 30 mg center dot sulfur center dot kg-1, as SO42-) in flooded soil. The results demonstrated that both W and S applications alone enhanced RIS formation, and their coapplication exhibited synergistic effects. Compared to the control, the co-application of W and S increased the proportion of RIS in total S by 76 % (90 %), 70 % (54 %), and 94 % (65 %) with 0.1 %, 0.5 %, and 1.0 % W at the early (middle) stages of incubation, respectively. The increase of RIS was attributed to the enhanced reduction of iron oxides and SO42-, mediated by reducing bacteria (especially Fe reducing bacteria) under low pe + pH. Besides, W addition increased AS levels during the early stage irrespective of S application, especially at 1 % W, due to organic sulfate mineralization. In addition, the influence of W and S applications on S transformation diminished over time. These findings suggest that the co-application of W and S under waterlogged soil could optimize sulfate bioavailability and RIS formation, which could meet the demand of rice sulfur nutrition and contribute to soil pollution remediation.

Landfill ecosystems represent significant terrestrial carbon sinks, where municipal solid waste (MSW) undergoes decomposition and transformation through biochemical reactions mediated by multi-kingdom microbiome. However, the spatial and temporal characterization of microbial interactions and collaboration within these multi-kingdom microbiomes remain largely unknown. In this study, we reveal the hierarchical and collaborative mechanisms by which multi-kingdom microbiomes drive carbon, nitrogen, phosphorus, and sulfur cycling across a 30-meter landfilling depth, corresponding to a landfilling age of 1 to 4 years. Through integration of metagenomics and network analyses, we elucidated vertical succession patterns in microbial community structure and function. The surface layer (1-2 years) was centered on bacterial-dominated primary metabolism, with Enterococcus aquimarinus and Brevundimonas bullata inferred to mediate metabolic coupling through fermentation, nitrogen fixation andphosphorus solubilization. Concurrently, phage-driven host lysis may contribute to the suppression of acidification. In the middle layer (2-3 years), co-occurrence patterns between archaea and fungi suggest mutualistic interaction supporting methanogenesis, wherein fungi such as Anaeromyces robustus would supply key substrates for methanogens such as Methanofollis ethanolicus. In the bottom layer (3-4 years), fungi, bacteria, and viruses collaborate under nutrient-limited conditions, with phages employing a "kill-the-winner" approach to sustain ecosystem function and stability. Collectively, our findings indicate that key microbial connectors across kingdoms contribute to elemental cycling through cross-kingdom interaction, including substrate exchange and nutrient supply. This study advances our understanding of multi-kingdom microbial dynamics during MSW decomposition and offers a conceptual framework for enhancing biogeochemical cycling efficiency within landfill ecosystems.

Straw incorporation and sulfur fertilizer are considered promising agronomic practices for remediating cadmium (Cd)-contaminated soil. However, their combined effects on Cd availability and soil bacterial communities in paddy soil remain unclear and may vary depending upon initial soil Cd levels. In this study, we conducted a 162day incubation experiment under waterlogged conditions, applying wheat straw (0 and 1 % w/w) and sulfate (0 and 30 mg kg- 1) individually or in combination to soils with high Cd (3.18 mg Cd kg- 1) and low Cd (0.18 mg Cd kg- 1) contamination. At the early stage, straw alone (W) or in combination with sulfate (W + S) reduced dissolved Cd concentration in both the low- and high-Cd soils. However, an increase in exchangeable Cd was observed only in the low-Cd soil during this period. Sulfate application (S) alone had no significant effect on either dissolved or exchangeable Cd. Both W and W + S treatments reduced bacterial community alpha diversity in the low- and high-Cd soil, primarily effecting the relative abundance of Firmicutes, Bacteroidota, Proteobacteria, and Acidobacteriota. Change in bacterial communities and soil properties, including an increase in dissolved organic carbon and decreases in Eh and pH, were associated with shifts in Cd availability. The effect of straw and sulfate application on Cd availability and bacterial community diversity varied with Cd contamination levels. Overall, straw incorporation, either alone or with sulfate, may help reduce Cd availability and modulate microbial communities in high-Cd paddy soil.

Preterm infants often exhibit gut dysbiosis and neurodevelopmental impairments, with evidence suggesting a crucial role of the microbiota-gut-brain axis in early development. To investigate whether probiotic intervention could improve these outcomes, we examined the effects of Clostridium butyricum and Bifidobacterium (LCBBCP) on gut microbiota diversity, spatial memory, and anxiety in preterm mice. We established a preterm mouse model divided into three groups: preterm + LCBBCP group, preterm control, and full-term control (n = 21 each). The preterm + LCBBCP group received LCBBCP oral gavage, while controls received saline. Gut microbiota analysis through 16 S rRNA gene sequencing revealed higher richness and evenness at postnatal day 21(P21) than postnatal day 14 (P14) across all groups, with preterm controls showing significantly lower microbial diversity at P14 compared to full-term controls. The preterm control group exhibited elevated levels of Enterobacteriaceae (37.586), Ruminococcaceae (1.7599), Streptococcaceae (1.0437), and Gemellaceae (0.3002) at P14, while Lactobacillaceae levels were higher in full-term control (13.7202 at P14 and 4.1571 at P21) and preterm + LCBBCP group (21.0084 at P14 and 10.9367 at P21) at both timepoints. Behavioral tests showed that preterm + LCBBCP group mice performed better than preterm controls in spatial memory tasks and displayed reduced anxiety-like behaviors, although not reaching full-term control levels. The preterm control group showed significantly reduced movement, slower speed, and increased resting time in open field tests. These findings demonstrate that LCBBCP intervention enhanced microbial diversity, improved spatial learning, and alleviated anxiety-like behaviors in preterm mice, likely through reducing Enterobacteriaceae and promoting Lactobacillaceae, suggesting a potential therapeutic strategy for preterm-related complications.

Tris(2,4-di-tert-butylphenyl) phosphite (Irgafos 168) is a widely used organophosphorus antioxidant and stabilizer in the plastics industry, valued for its ability to enhance the stability and durability of plastics. However, Irgafos 168 can leach from plastics into the environment, leading to its accumulation and posing potential risk on human health and the ecosystem. Synthetic microbial consortium is a promising and environment-friendly approach to mitigate the environmental impact of Irgafos 168. This study aimed to construct simple and efficient microbial consortia for Irgafos 168 biodegradation. The bacterial strains isolation strategy is based on “relay”biodegradation principal, utilizing Irgafos 168 and its primary degrdation products (bis (2,4- di-tert-butylphenyl) hydrogen phosphate and 2,4-di-tert-butylphenol) as energy and carbon source. Three microbial consortia were then developed as consortium 1 with the best bacterial isolate for Irgafos 168 (Serratia sp. LY-1) biodegradation and the best bacteria isolate for bis (2,4-di-tert-butylphenyl) hydrogen phosphate (Bacillus pacificus) biodegradation in the ratio 1:1, consortium 2 with Serratia sp. LY-1 and the best bacteria isolate for 2,4-di-tert-butylphenol (Ochrobactrum sp. AU-1) biodegradation in the ratio 1:1, consortium 3 with Serratia sp. LY-1, Bacillus pacificus, Ochrobactrum sp. AU-1 in the ratio 1:1:1. After 72 hours of incubation, consortium 1 and consortium 3 achieved complete (100%) biodegradation of Irgafos 168, significantly outperforming the 70% Irgafos 168 biodegradation by single Serratia sp. LY-1. This study highlights an effective and straightforward method for microbial consortia construction for Irgafos 168 biodegradation, offering a promising strategy for industrial application.

Microplastics and nanoplastics are pervasive environmental pollutants infiltrating freshwater and terrestrial ecosystems worldwide. Despite increasing recognition of their ecological impacts, the effects of these particles on insect populations remain poorly understood. Insects, which are critical for pollination, decomposition, and nutrient cycling, are increasingly exposed to microplastics and nanoplastics, potentially leading to biological harm. This study presents the first global meta-analysis that evaluates the toxicity of microplastics and nanoplastics on insect health. Our findings reveal that microplastic significantly impairs key biological traits, including survival (-1.17), growth (-0.69), development (-0.69), feeding (-0.68), fecundity (-0.47), and behavior (-0.24), with survival being the most adversely affected trait. While nanoplastics also pose risks, their effects are generally less severe than those of microplastics. Moderators such as plastic type, concentration, and exposure duration critically influence the severity of toxic effects, with higher concentrations and longer exposures leading to greater harm. These reductions in biological fitness underscore the potential for microplastics and nanoplastics to disrupt essential ecosystem functions.

Rice consumption serves as a primary pathway for human dietary exposure to methylmercury (MeHg), a potent neurotoxin predominantly formed in paddy soils. Although soil physicochemical properties exert a strong influence on MeHg production and accumulation, soil heterogeneity has hindered the identification of consistent controlling factors. In this study, a systematic meta-analysis of 22 peer-reviewed datasets was conducted to evaluate environmental regulators of MeHg contamination in paddy soils, with a specific distinction made between sites located within and outside Hg mining areas. The results revealed significantly elevated Hg and MeHg levels in paddy soils associated with Hg mining activity. Across both site types, soil pH, organic matter (OM), and total Hg (THg) were identified as key determinants of MeHg dynamics. MeHg accumulation was highest under weakly alkaline conditions (pH 7.0-8.0), while both low (<10 g/kg) and high OM (>60 g/kg) OM levels were unfavorable for MeHg accumulation. In Hg mining area paddy fields, maximum %MeHg occurred at OM levels of 30-40 g/kg, whereas in ordinary paddy fields, the optimal range was 20-30 g/kg. In addition, rice cultivation significantly absorbs soil MeHg. In acidic paddy soils, modest pH reduction coupled with appropriate OM amendments may suppress MeHg production. These findings offer important insights for the targeted management and remediation of Hg and MeHg in paddy soil.

The United Nations has identified municipal solid waste (MSW) landfills as significant reservoirs of antibiotic resistance genes (ARGs). Although ARG profiles, their primary drivers, and associated hosts have been well characterized in landfill leachate, such information remains limited for MSW landfills, which are the original source of the resistome. This knowledge gap impedes effective ARG monitoring at the source and poses challenges for public health management. Herein, we investigated the profiles of ARGs, their potential drivers, and associated hosts in refuse samples collected from a large-scale landfill using metagenomic sequencing and quantitative polymerase chain reaction analysis. Our findings revealed that landfills harbor diverse ARGs, with multidrug resistance genes (MDRGs) emerging as the dominant class, accounting for 39.78% of all ARGs detected. Notably, MDRGs exhibited high mobility potential (associated with plasmids, phages, and mobile genetic elements (MGEs)) and were frequently colocated with virulence factors. Pseudomonas, Acinetobacter, and Brevundimonas were identified as key MDRG hosts. Partial least-squares path modeling analysis indicated that MDRG variation was driven by multiple factors (i.e., MGEs, metal resistance genes (MRGs), hosts, and environmental factors). Additionally, metagenome-assembled genomes were found to carry multiple MDRGs. Collectively, these results underscore the role of landfills as critical hotspots for MDRGs.

Microbial community coalescence describes the mixing of microbial communities and their integration with the surrounding environment, which is common in natural ecosystems and has potential impacts on ecological processes. However, few studies have focused on microbial community coalescence between different habitats in estuarine regions. In this study, we comprehensively investigated the environmental characteristics and bacterial community changes of different habitats (water body (Water), subtidal sediments (SS) and intertidal salt marsh sediments (SM)) in Luanhe estuary during flood and normal flow periods. The results showed that flood event significantly reduced the salinity of the estuarine habitats, changed the nutrient structure and intensified the eutrophication of estuarine water. By calculating the proportion of overlapping groups and applying the ‘FEAST’ algorithm, we revealed that flood event facilitated the migration of bacterial communities along alternative pathways across habitats, markedly enhanced the cross-habitat mobility of bacterial communities, which underscores the pivotal role of flood event in driving bacterial community coalescence. Flood-induced community coalescence not only increased the α-diversity of bacterial communities within habitats, but also increased the proportion of overlapped species between habitats, ultimately leading to homogenization between habitats. Canonical correlation analysis combined co-occurrence network analysis revealed that flood event attenuated the role of environmental filtration in microbial assembly, while increased the impact of dispersal processes and intensified interspecific competition among microorganisms, led to the change of keystone species and reduced the complexity and stability of bacterial communities. In conclusion, this study demonstrates the complex effects of flood events on estuarine microbial communities from the perspective of multi-habitat interactions in the estuary, and emphasizes the key role of river hydrodynamic conditions in facilitating the coalescence of estuarine microbial communities. We look forward to further attention and research on estuarine microbial coalescence, which will provide new insights into assessing the stability and resilience of estuarine ecosystems under flood challenges and the sustainable management of estuarine wetlands.

Viruses manipulate bacterial community composition and impact wastewater treatment efficiency. Some viruses pose threats to the environment and human populations through infection. Improving the efficiency of wastewater treatment and ensuring the health of the effluent and receptor pools requires an understanding of how viral communities assemble and interact with hosts in wastewater treatment plants (WWTPs). We used metagenomic analysis to study the distribution, assembly mechanism, and sensitive hosts for the viral communities in raw water, anaerobic tanks, and returned activated sludge units of a large-scale industrial park WWTP. Uroviricota (53.42% ± 0.14%) and Nucleocytoviricota (26.1% ± 0.19%) were dominant in all units. Viral community composition significantly differed between units, as measured by β diversity (P = 0.005). Compared to raw water, the relative viral abundance decreased by 29.8% in the anaerobic tank but increased by 9.9% in the activated sludge. Viral community assembly in raw water and anaerobic tanks was predominantly driven by deterministic processes (MST <0.5) versus stochastic processes (MST >0.5) in the activated sludge, indicating that differences in diffusion limits may fundamentally alter the assembly mechanisms of viral communities between the solid and liquid-phase environments. Acidobacteria was identified as the sensitive host contributing to viral abundance, exhibiting strong interactions and a mutual dependence (degree = 59). These results demonstrate the occurrence and prevalence of viruses in WWTPs, their different assembly mechanism, and sensitive hosts. These observations require further study of the mechanisms of viral community succession, ecological function, and roles in the successive wastewater treatment units.

Antimony (Sb) pollution seriously endangers ecological environment and human health. Microbial induced mineralization can effectively convert metal ions into more stable and less soluble crystalline minerals by extracellular polymeric substance (EPS). In this study, an efficient Sb-resistant Rhodotorula mucilaginosa (R. mucilaginosa) was screened, which can resist 41mM Sb(III) and directly transform Sb(III) into Sb2O3 microcrystals by EPS. The removal efficiency of R. mucilaginosa for 22mM Sb(III) reached 70% by converting Sb(III) to Sb2O3. The components of supernatants as well as the effects of supernatants and pH on Sb(III) mineralization verified that inducible and non-inducible extracellular protein/polysaccharide biomacromolecules play important roles in the morphologies and sizes control of Sb2O3 formed by R. mucilaginosa respectively. Sb2O3 microcrystals with different morphologies and sizes can be prepared by the regulation of inducible and non-inducible extracellular biomacromolecules secreted by R. mucilaginosa. This is the first time to identify that R. mucilaginosa can remove Sb(III) by transforming Sb(III) into Sb2O3 microcrystals under the control of EPS. This study contributes to our understanding for Sb(III) biomineralization mechanisms and provides strategies for the remediation of Sb-contaminated environment.

Methylmercury formation is mainly driven by microbial-mediated process. The mechanism of microbial mercury methylation has become a crucial research topic for understanding methylation in the environment. Pioneering studies of microbial mercury methylation are focusing on functional strain isolation, microbial community composition characterization, and mechanism elucidation in various environments. Therefore, the functional genes of microbial mercury methylation, global isolations of Hg methylation strains, and their methylation potential were systematically analyzed, and methylators in typical environments were extensively reviewed. The main drivers (key physicochemical factors and microbiota) of microbial mercury methylation were summarized and discussed. Though significant progress on the mechanism of the Hg microbial methylation has been explored in recent decade, it is still limited in several aspects, including (1) molecular biology techniques for identifying methylators; (2) characterization methods for mercury methylation potential; and (3) complex environmental properties (environmental factors, complex communities, etc.). Accordingly, strategies for studying the Hg microbial methylation mechanism were proposed. These strategies include the following: (1) the development of new molecular biology methods to characterize methylation potential; (2) treating the environment as a micro-ecosystem and studying them from a holistic perspective to clearly understand mercury methylation; (3) a more reasonable and sensitive inhibition test needs to be considered. Key points • Global Hg microbial methylation is phylogenetically and functionally discussed. • The main drivers of microbial methylation are compared in various condition. • Future study of Hg microbial methylation is proposed. Graphical Abstract

Anthropogenic activities significantly impact river ecosystem nutrient fluxes and microbial metabolism. Here, we examined the seasonal and spatial variation of sediments physicochemical parameters and the associated microbiome in the Pengxi river, a representative tributary of Three Gorges Reservoir, in response to seasonal impoundment and land use change by human activities. Results revealed that seasonal impoundment and land use change enhanced total organic carbon (TOC), total nitrogen (TN) and ammonium nitrogen (NH4+-N) concentration in the sediment, but have different effects on sediment microbiome. Sediment microbiota showed higher similarity during the seasonal high-water level (HWL) in consecutive two years. The abundant phyla Acidobacteria, Gemmatimonadetes, Cyanobacteria, Actinobacteria and Planctomycetes significantly increased as water level increased. Along the changes in bacterial taxa, we also observed changes in predicted carbon fixation functions and nitrogen-related functions, including the significantly higher levels of Calvin cycle, 4HB/3HP cycle, 3HP cycle and assimilatory nitrate reduction, while significantly lower level of denitrification. Though land use change significantly increased TOC, TN and NH4+-N concentration, its effects on spatial variation of bacterial community composition and predicted functions was not significant. The finding indicates that TGR hydrologic changes and land use change have different influences on the carbon and nitrogen fluxes and their associated microbiome in TGR sediments. A focus of future research will be on assessing on carbon and nitrogen flux balance and the associated carbon and nitrogen microbial cycling in TGR sediment.