搜索结果：Molecular ecology

Microplastics are a pervasive pollutant with impacts on organisms across ecosystems. As species increasingly live in the presence of plastic pollution, there is a need to deepen our understanding of biological responses to microplastics. To this end, we performed an experiment exposing fathead minnows (Pimephales promelas) to different microplastic treatments. We tested two polyethylene microplastic concentrations, reflecting current and predicted future conditions, of two plastic origins: pre-consumer plastic (never exposed to natural environments) and plastic gathered from Lake Ontario. We performed weighted gene co-expression analysis on liver tissue using directional mRNA sequencing data to evaluate gene expression among different treatments across sexes and to explore correlations with ecotoxicological metrics. We addressed the following questions: 1) is there a significant effect of microplastic exposure on gene expression, 2) if there are changes in gene expression attributed to microplastic exposure, do these effects differ across plastic concentration and/or plastic origin, and 3) does the effect of microplastics exposure vary by sex? Our findings provide evidence of metabolic changes in fish exposed to microplastics. Many of the gene modules found in our analysis correspond to cellular stress responses, further increasing the evidence that microplastic exposure has molecular effects on organisms. Furthermore, we found these molecular effects differed by sex, with a greater response found in females. As fathead minnows are an important model species, these results have important implications across aquatic species and ecosystems. Understanding how persistent pollutants, such as microplastics, may stress organisms across levels of biological organization will be key to mitigating anthropogenic change at various levels, from the molecular to the population and community levels.

Cadmium pollution posed a serious threat to eco-environmental security, but molecular variation in microalgae induced by cadmium remains unknown. To address this, we screened the molecular dynamics in Synechocystis sp. PCC 6803 exposed to an environmentally relevant Cd2+ concentration (0.05 mg·L-1) over 0-144 hours. Differential express genes/proteins (DEGs/DEPs) and expression levels divided the exposure process into two stages. The response phase (0-24 h) was characterized by the rapid, transient, and highly specific gene/protein activation; the top uniquely DEGs/DEPs included nrsA (cation-efflux), PsbA1/T (Photosystem II protein) and Ssl1911 (glutamine synthetase) were defined as stage-specific molecular signatures. Their expression peaked before 24 h and showed no significant change thereafter. The adaptive phase (24-144 h) was characterized by the sustained and synergistic proteomic dynamic regulation, 145 co-expressed DEPs were identified, cadmium influx-associated transporters (MntCAB/FeoB) were suppressed, efflux systems (Slr0944/ZiaA) were induced coupled with enhanced central carbon metabolism (carbon fixation, oxidative phosphorylation, TCA cycle) and elevated antioxidant enzyme activity (Slr1516). It was concluded DEGs/DEPs involved in photosynthetic processes and antioxidant defense changed significantly within 24 hours. These changes were followed by adaptive mechanisms, including down-regulating inward Cd2+ transporters while simultaneously up-regulating efflux pumps, as well as enhancing energy metabolism and antioxidant capacity. This dynamic pattern provided insight into the interaction between cyanobacterial cells and cadmium ions.

Traditional bacterial classification relies on phenotypic traits (e.g., morphology and metabolic profiles), but these methods lack resolution for closely related taxa and are biased by culture conditions. While 16S rRNA gene sequencing is a widely used molecular complement, it fails to resolve closely related Peptostreptococcaceae species, including Clostridioides difficile. These limitations have caused family-level taxonomic confusion and ambiguous Clostridioides genus boundaries, hindering clinical identification of pathogenic strains and posing public health risks. To address these limitations, we developed an integrated approach combining multi-scale phylogenomic and protein-based molecular evidence, adopting a hierarchical workflow: first, constructing a 16S rRNA phylogeny of 151 Firmicutes strains to demonstrate traditional marker inadequacies; second, generating a whole-genome protein phylogeny of 51 representative Peptostreptococcaceae genomes and defining taxonomic boundaries via average amino acid identity (AAI); third, analyzing spore-associated protein patterns across C. difficile isolates and related genomes. Results revealed high conservation of C. difficile spore coat/exosporium proteins and clear genus-level phylogenetic distinctiveness of these proteins. Combined with AAI-validated whole-genome data, our findings support key Peptostreptococcaceae taxonomic revisions: redefining polyphyletic Romboutsia, reassigning Eubacterium tenue to Paraclostridium, and elevating Alkalithermobacter to genus status. This study establishes spore coat proteins as core taxonomic markers for spore-forming bacteria, with our integrated strategy overcoming traditional limitations to improve classification accuracy and C. difficile surveillance.IMPORTANCEConventional classification struggles to resolve closely related Peptostreptococcaceae species (e.g., Clostridioides difficile). We developed an integrated framework combining 16S rRNA sequencing, whole-genome protein analysis, and spore trait assessment, with a key innovation: identifying spore coat/exosporium proteins as robust, conserved taxonomic markers. This approach enabled three pivotal Peptostreptococcaceae revisions-redefining Romboutsia, reassigning Eubacterium tenue to Paraclostridium, and elevating Alkalithermobacter to genus rank. The findings resolve a longstanding microbial systematics bottleneck for spore-forming bacteria, provide critical taxonomic context for C. difficile's precise monitoring and prevention, and expand taxonomic markers beyond nucleic acid-based methods. This advances classification precision, critical for microbial ecology, pathogenesis, and industrial microbiology research.

Developing highly selective adsorbents for antibiotic removal from aquatic environments is often hindered by the instability of molecular recognition sites in aqueous media. Traditional molecularly imprinted polymers (MIPs) frequently exhibit impaired performance in water due to the disruption of non-covalent interactions. This study presented a general strategy for the fabrication of "greenificated" MIPs utilizing a deep eutectic solvent (DES) as both a functional monomer and a structure-directing porogen in a one-pot synthesis. The resulting polymer, MIP-DES/(20% MeOH), targeted sulfamethoxazole (SMX) through a "solvent-reactant synergy" mechanism. Under optimized conditions, the adsorbent achieved a maximum capacity of 59.58 mg/g and an imprinting factor of 1.80. Mechanistic elucidation using density functional theory (DFT) and spectroscopic analysis confirmed that the recognition was governed by specific hydrogen bonding, π-π interactions, and hydrophobic effects, which remained stable despite interference from competitive analytes, 12 water matrices and natural organic matter. Comprehensive assessments including AGREEMIP, life cycle analysis, biological toxicity, and long-term desorption together confirmed environmental friendliness of both pristine and SMX-saturated adsorbent. This work demonstrates that DES-mediated imprinting provides a robust pathway for the sustainable production of high-performance materials capable of selective recognition in complex engineered and natural water systems.

Breeding semi-dwarf cultivars has long been a major objective for wheat improvement due to the inseparable association between plant height (PH) and grain yield. Although the utilization of Rht-B1b and Rht-D1b genes successfully achieved semi-dwarfism in the 1960s, these genes were associated with undesirable traits. The current wheat breeding urgently requires continuously exploring PH-controlling genes and their regulatory mechanisms, which will expand the genetic diversity of the PH gene pool to achieve precise PH regulation while maintaining or even increasing the grain yield potential. In this study, we identified a gibberellin (GA)-sensitive dwarf mutant, designated wph3 (wheat plant height 3). It showed GA biosynthesis deficiency and had pleiotropic effects on PH, spike length, grain weight, and grain number per spike. Using Exome Capture Sequencing for Bulked Segregant Analysis and molecular marker mapping, a novel recessive nuclear dwarfing gene was identified and localized into a ~ 3.9 Mb physical interval on chromosome 2B, designated Rht29 (Reduced height 29). Transcriptome analysis and candidate gene mining indicated that Rht29 may not encode a canonical key enzyme for GA biosynthesis, but participate in the GA biosynthesis by regulating the expression level of GA3ox. This study enriches the genetic resources available for wheat dwarfing breeding and establishes a foundation for further molecular characterization of phenotypic regulation by Rht29.

Organic UV filters are widely used in personal care products and are increasingly being detected in aquatic environments, where they may pose a risk to aquatic organisms. Avobenzone (AVO) is one of the most widely used of these compounds worldwide. The European Commission has included it among substances to be systematically monitored across EU Member States due to concerns regarding its environmental fate and potential ecological risks. The available literature indicates that avobenzone can cause adverse biological effects in a wide range of aquatic species. However, research into the effects of avobenzone on fish is extremely limited, and no data on gill toxicity are currently available. In this study, we investigated the effects of two environmentally relevant concentrations of AVO (3 and 9 μg/L) on the gills of zebrafish (Danio rerio) under short-term (4 days) and long-term (21 days) exposure conditions. Morphological, ultrastructural, morphometric and molecular endpoints were evaluated to provide a comprehensive assessment of AVO-induced toxicity. Our results demonstrate that exposure to AVO induces pronounced, time- and dose-dependent alterations in gill tissue. These include chloride cell hypertrophy, epithelial lifting, macrophage proliferation and increased filament thickness and lamellar width, alongside reduced lamellar length. Furthermore, AVO exposure was found to significantly modulate the expression of genes involved in osmoregulation (atp1a1a.1 and aqp3a), the oxidative stress response (sod and cat) and apoptosis (casp3, casp8 and casp9). Overall, our findings provide novel evidence of avobenzone-induced gill toxicity in adult zebrafish and contribute to improving the environmental risk assessment of UV filters in aquatic ecosystems. Additionally, the information presented here underscores the importance of integrating morphological and molecular approaches when evaluating the toxic potential of emerging contaminants.

The effectiveness of antibiotic therapy for urogenital tract infections (UTIs) is increasingly compromised by the global dissemination of extended-spectrum β-lactamase-producing Enterobacterales (ESβL-En). This study aimed to assess the involvement of broad-spectrum β-lactamase-producing Enterobacterales (BSβL-En) in UTIs and to establish their antibiotic susceptibility profile. A cross-sectional study was conducted from October to December 2019 at the Army Training Hospital Omar Bongo Ondimba. All patients suspected of having a UTI were included. BSβL-En isolates were recovered using MacConkey agar supplemented with cefotaxime. Phenotypic screening for β-lactamase (ESβL, AmpC, and carbapenemases) using specific phenotypic confirmatory disc diffusion test. Antimicrobial susceptibility was determined using the disk diffusion method and minimum inhibitory concentration (MIC) assays. The presence of resistance genes (bla CTX-M, bla TEM, bla CARBA, bla IMP, mcr-1 and mcr-2) was investigated by polymerase chain reaction. A total of 295 patients were enrolled, among whom 18.3% (54/295) had UTIs. Of the isolated uropathogens 74.1% were BSβL-En. The predominant species were Enterobacter cloacae (8/54, 14.8%), Escherichia coli (6/54, 11.1%) and Kluyvera spp (5/54, 9.3%). Among 40 BSβL-En isolates, 87.5% (n = 35/40) were confirmed by molecular analysis. Notably 48.5% (17/35) harbored at least two bla genes, simultaneously. Fourteen isolates carried the bla CARBA and bla IMP genes, which in combination with the bla CTX-M and bla TEM. About 40.0% of the isolates (14/35) carried the bla CTX-M, 8.6% had the bla TEM (3/35), and 2.9% had the bla IMP (n = 1/35). All urinary isolates were multidrug-resistant (MDR), exhibiting high levels of β-lactamase production, with resistance rates of 81.6% ± 0.16% for first-line antibiotics (e.g., β-lactams, fluoroquinolones) and 61.7% ± 0.04% for last-resort antibiotics (e.g., imipenen, ertapenem, and colistin). The prevalence of carbapenem resistance genes was 44.1%, whereas no colistin resistance genes (mcr-1 and mcr-2) were detected. This study highlights a high prevalence of multidrug-resistant uropathogens producing BSβL, with significant resistance to both first-line and last-resort antibiotics.

Life cycle details or ecological impact are well characterized only for a few ssDNA phages. The Finnlakeviridae family includes one species, Finnlakevirus FLiP. Here, using the same Flavobacterium host and sampling location, we isolated a new strain designated FLiP-2, with 96.7% genetic identity to the original isolate FLiP. To understand the ecology of this Flavobacterium-infecting phage species, we explored the host interactions of the two FLiP strains and a dsDNA Flavobacterium phage MaF61 under various conditions representing those encountered in their natural habitats in boreal lakes including different temperatures, anoxic conditions, and in the presence of different nutrients and antibiotics. While FLiP and FLiP-2 had similar virion stability outside the host, they exhibited significant differences in plaque morphology and infectivity. FLiP-2 could not replicate in the presence of ampicillin, whereas FLiP thrived even at high concentrations. Both strains of Finnlakevirus FLiP propagated better under or after stress exposure compared to MaF61. Additionally, Finnlakevirus FLiP plaques appeared far from the original infection site, particularly in response to stress, suggesting non-lytic presence within a motile or filamentous bacterium. In conclusion, Finnlakevirus FLiP showed remarkable flexibility in host-interactions being well adapted to fluctuating conditions in boreal freshwaters.

暂无摘要（点击查看详情）

Microplastics and acid rain (AR) are increasingly recognized as co-occurring pollutants in agricultural ecosystems; however, their combined effects on cadmium (Cd) toxicity in crops remain poorly understood. This study investigated the individual and combined effects of polyvinyl chloride (PVC) microplastics and AR on Cd toxicity in rice (Oryza sativa L.) roots under 0.3, 3, and 10 mg/L Cd exposure. PVC alone consistently reduced Cd accumulation and alleviated Cd-induced growth inhibition, whereas AR exerted concentration-dependent effects. Under high Cd stress (10 mg/L), PVC + AR coexposure induced a distinct, non-additive physiological response characterized by increased CAT and SOD activities (6.0-25.5% and 2.3-6.0%, respectively) and reduced MDA accumulation (23.1-29.8%) relative to Cd treatment alone. Three-way ANOVA further revealed significant interaction effects among Cd, PVC, and AR on root growth, oxidative regulation, and elemental homeostasis. Transcriptomic analysis and weighted gene coexpression network analysis (WGCNA) identified key modules associated with Cd responses, which were enriched in glutathione metabolism, antioxidant defense, ion transport, and stress signaling pathways. qRT-PCR analysis confirmed the suppression of Cd uptake-related transporters (OsNramp5 and OsHMA2) and the induction of detoxification-associated genes (OsGSTUs and OsNASs) under PVC and/or AR treatments. Collectively, these findings demonstrate that co-occurring environmental pollutants can trigger non-additive physiological and transcriptional responses in rice roots, providing new insights into plant adaptation to composite pollution and offering potential targets for ecological risk assessment and for improving crop resilience and food safety.

Dimethylsulfoniopropionate (DMSP) is a highly abundant marine organosulfur compound, with important roles in stress protection and climate-cooling gases production. Polar regions, particularly seawater and sea ice interfaces, are critical yet understudied DMSP cycling hotspots. Here, we reveal up to 38-fold higher DMSP concentrations in Southern Ocean sea ice versus seawaters, identifying sea ice as a concentrated reservoir of DMSP with implications for microbial stress tolerance and sulfur recycling. Eukaryotic algae harboring DSYB and DSYE genes were predicted to dominate DMSP production, but diverse and previously unidentified bacterial producers were also detected. This elevated abundance of algal biosynthetic genes likely underpins the higher DMSP concentrations in sea ice. Notably, DMSP catabolism, particularly the dmdA demethylase and dddD and dddK lyase genes, were more abundant than biosynthesis genes. Taken together, these findings reveal the widespread metabolism for DMSP cycling and underscore a dynamic reservoir and transformation hub influencing polar climate-cooling sulfur fluxes.

Enterocytozoon bieneusi is an important zoonotic pathogen. This study examined its prevalence and genotypes in Siberian tigers in Northeast China. Fecal samples from 97 captive and 5 wild tigers were analyzed by nested PCR targeting the ITS region. Prevalence in captive tigers was 40.2% (39/97), with no significant site differences. Three genotypes were identified: D (89.7%), Peru8 (7.7%), and Type IV (2.6%), all within zoonotic Group 1. E. bieneusi was detected for the first time in a wild Siberian tiger (genotype D). The predominance of genotype D-common in poultry-suggests dietary transmission through contaminated chicken meat. These results indicate high prevalence of zoonotic genotypes in tigers, underscoring cross-species transmission risks and the need for strengthened biosecurity and surveillance.

The timing of divergence between hominins and the bonobo-chimpanzee clade has been at the core of palaeoanthropological debate for over a century. The earliest molecular studies indicated divergence times ranging from 5 Ma to as recently as 1.3 Ma. This study critically reviews the trends of time estimates published between 1967 and 2023, and analyses how these are supported or rejected by the current molecular and fossil records. We compiled 202 divergence estimates and defined three distinct thresholds based on fossil evidence at 4.4 Ma (Australopithecus anamensis and Ardipithecus ramidus), 6.2 Ma (Orrorin tugenensis and Ardipithecus kadabba), and 7.2 Ma (Sahelanthropus tchadensis). We then used these thresholds to filter out molecular estimates that are too young to fit the fossil record. Overall, the data suggests a divergence event within the late Miocene, with each threshold pushing it further back, 8.63-6.38, 10.33-7.81, and 10.95-8.81 Ma, respectively. We use a quadratic regression to demonstrate that estimates have been slowly shifting from ~ 6 Ma to ~ 8.5 Ma over the past 56 years. A Bayesian meta-analysis of genomic estimates filtered by our most consensual threshold (i.e., assuming Australopithecus belongs to Hominini) indicates that the split must have occurred early in the late Miocene, most likely before 7 Ma (~ 99.5% posterior probability) with a pooled effect of 8.69-7.28 Ma. We conclude that, despite an initial bias towards younger estimates, the molecular timing for the last common ancestor (LCA) of Pan-Homo has been progressively approaching the intervals suggested by the current fossil record.

The present study engineered a bioactive seed coating based on molecularly optimized chitosan-salicylic acid (SA-CS) networks to fortify folate biosynthesis in wheat seedlings. Among tested phytohormones, salicylic acid (SA) promoted seedling growth, folate accumulation, and antioxidant capacity. Composite coatings were fabricated using chitosan of varying molecular weights; films formulated with 0.3% medium molecular weight chitosan and 0.1% SA (SA-MCS) exhibited moderate water vapor permeability and sustained release, creating a favorable microenvironment for germination. SA-MCS coatings significantly increased total folates from 569.87 to 702.75 μg 100 g-1 DW. Mechanistically, controlled SA delivery upregulated GTP cyclohydrolase 1 (GCH1) and aminodeoxychorismate synthase (ADCS), accelerating metabolic flux into the pterin and para-aminobenzoic acid (pABA) branches. Multiomics analysis revealed coordinated mobilization of carbon units from histidine catabolism and glutamate into one-carbon metabolism, providing structural backbones and methyl groups for folate enrichment. These findings demonstrate SA-CS coatings as an efficient, biodegradable seed delivery platform for eco-friendly folate biofortification.

Schistosomiasis, caused by blood flukes of the genus Schistosoma, is a neglected tropical disease whose transmission depends on freshwater snails. Oncomelania hupensis is the obligate intermediate host for Schistosoma japonicum, disrupting this snail-schistosome relationship is therefore a crucial strategy for disease control and elimination. However, current snail-directed control methods are limited and can adversely affect biodiversity, ecological balance, and environmental health, underscoring the need for deeper mechanistic understanding of factors that naturally regulate schistosome transmission. Notably, prior infection with Exorchis sp. has been shown to completely block subsequent infection by S. japonicum in O. hupensis through within-host competitive exclusion. Therefore, elucidating the biological dynamics and molecular mechanisms underlying this interference competition may thus contribute to the development of novel anti-schistosome strategies. This review systematically synthesizes current knowledge on the life cycle of Exorchis sp., the mechanisms driving its competitive dominance over S. japonicum, field surveys of its natural distribution, and the underlying immunological mechanisms. By integrating these facets, we aim to advance fundamental understanding of within-host trematode competition and its implications for schistosomiasis transmission ecology. We further discuss how insights into the molecular and immunological mechanisms of this interaction may inform future targeted interventions. Finally, this work presents a unique opportunity to investigate gastropod immunity and host-parasite co-evolutionary dynamics, thereby broadening our knowledge of molluscan immune competence and its role in shaping disease transmission.

Substitutional entrenchment arising from epistatic interactions renders previously acceptable amino-acid states unfavorable over evolutionary time and has often been attributed to novel adaptive processes. However, recent simulations based on Potts-Hamiltonian models have suggested that entrenchment may also emerge during protein evolution governed by the neutral theory of molecular evolution (NTME). Here, we re-examine this conclusion by assessing whether substitutions permitted in such simulations are consistent with empirical expectations of NTME. Since Potts models are inferred from a large collection of homologous rather than orthologous sequences, they may allow substitutions that are incompatible with NTME. Our analysis revealed that Potts-based simulations permit amino-acid substitutions whose Hamiltonian energies (PHE, φ) often fall outside empirically derived NTME φ neighborhoods, thus allowing non-neutral evolution of domain sequences. To prevent such transgressions, we implement simulations that impose purifying selection whenever Potts-acceptable substitutions depart from the NTME φ neighborhood. When these substitutions are eliminated, we observed limited substitutional entrenchment, with site-specific amino-acid preferences remaining stable over biologically relevant timescales in neutral protein evolution. We further find that overdispersion of the molecular clock is modest and scales directly with the proportion of evolutionary lineages displaying epistasis-driven among-site rate heterogeneity, independent of entrenchment. These results demonstrate that significant entrenchment is not an inherent property of epistasis during protein evolution consistent with NTME. Our findings establish baseline expectations for neutral evolution with epistasis and suggest that pronounced entrenchment observed in natural protein evolution likely reflects non-neutral evolutionary histories, including adaptation.

Soils harbor the most complex microbial diversity on Earth, in which bacteria are ubiquitously infected by temperate phages. While integrated prophages often enhance host fitness, active (inducible) prophages are traditionally perceived as "molecular time bombs" due to their intrinsic lysis threat. This dual nature has raised fundamental questions about the true contribution of temperate phages to microbial adaptation and ecosystem stability. To address this gap, we conducted a global-scale integrative analysis by synthesizing 123,207 high-quality bacterial genomes, 183 soil-specific viromic data sets, and 3,749 metagenomes. We established the Global Soil Active Prophage Database (GSAPD), comprising 21,397 high-confidence active prophages, which we found to represent 34.3% of the total soil viral population within our analytical framework. Our comparative genomic analysis reveals that active prophages possess significantly larger genomes and greater genetic complexity compared with their dormant counterparts. Crucially, by mapping phage-encoded auxiliary metabolic genes (AMGs) across diverse biomes, we found that active prophages are disproportionately enriched in key pathways for carbon, nitrogen, and sulfur cycling, as well as specialized resistance mechanisms against heavy metal toxicity. These findings suggest that active prophages act as dynamic reservoirs of functional diversity. We demonstrate that their lytic potential is not merely a survival risk, but a sophisticated mechanism underpinning host environmental adaptation and niche expansion. Ultimately, this study provides a comprehensive global catalog of soil viral pathways and redefines the role of temperate phages as pivotal drivers of microbial evolution and biogeochemical cycling in terrestrial ecosystems.IMPORTANCESoils contain immense microbial diversity, yet the ecological role of temperate phages-especially their active (inducible) forms-remains poorly understood. This study provides the first global-scale assessment of active prophages in soils, revealing that they are widespread and functionally distinct from dormant forms. By building a comprehensive database and integrating multi-omics data, we show that active prophages are enriched in genes linked to key biogeochemical processes and stress resistance. These findings challenge the traditional view of active prophages as purely harmful agents and instead highlight their role as dynamic contributors to microbial function and adaptation. Our work offers new insights into how viruses shape ecosystem processes and provides a valuable resource for future studies on soil microbial ecology and nutrient cycling.

This study evaluated ectomycorrhizal compatibility, functional effects, and the inoculum-dose response of Lactarius quieticolor and Tuber floridanum in Pinus elliottii and Pinus taeda, aiming to understand the role of fungus-host specificity in the expression of growth and physiological responses. Basidiomes of Lactarius spp. used as the inoculum source were identified through morphological and molecular analyses, confirming the identity as L. quieticolor. The symbiont L. quieticolor formed ectomycorrhizae on both Pinus species, whereas T. floridanum established an association only with P. elliottii, representing the first experimental record of this interaction. In P. elliottii, both fungi elicited integrated responses regardless of dose, with increases in growth, root biomass and electron transport rate, while L. quieticolor also increased root length, phosphorus content and modulated initial chlorophyll fluorescence. In P. taeda, effects were more limited and dose-dependent: increases in shoot nitrogen content, electron transport rate and root colonization were observed only at the highest inoculum concentrations. Multivariate analyses revealed a clear separation between control and inoculated plants even as the fungal treatments, indicating specific functional signatures. Altogether, the results demonstrate that ectomycorrhizal compatibility is not universal among congeneric Pinus species and highlight the potential of L. quieticolor and T. floridanum as functional ectomycorrhizal symbionts, with implications for seedling production and the ecology of forest systems.

Wastewater treatment plant (WWTP) effluent is a significant source of environmental impacts, introducing substantial dissolved organic matter (DOM) and nutrients into receiving waters. However, the specific role of effluent-derived DOM (EDOM) in shaping microbial community structure and key metabolic functions remains insufficiently understood. We systematically explored the effects of EDOM on the seasonal dynamics of bacterial communities in effluent-receiving waters in a typical water-scarce region of North China. Our results revealed that WWTP effluent input significantly altered DOM characteristics, shifting them toward greater humification, increased recalcitrance, lower molecular mass, and simpler structure, against a background of elevated nutrient levels. The interplay between transformed EDOM and resident microorganisms collectively restructured the bacterial community and its potential metabolic functions. These changes included (i) increased taxonomic richness and a more specialized community composition; (ii) enhanced microbial network complexity with a polycentric architecture dominated by DOM components; (iii) seasonal convergence of microbial network structure, as strong EDOM-driven interactions in the dry season were attenuated by wet season hydrology; and (iv) strengthened coupling between DOM molecular traits and biogeochemical cycling potential. Crucially, EDOM was identified as the key driver controlling microbial richness and core metabolic processes, with its influence exhibiting significant seasonal dynamics across the carbon, nitrogen, and sulfur cycles. While current Chinese wastewater discharge standards regulate nutrient inputs, they lack consideration of ecological risks posed by EDOM fractions and their dynamic interactions with microorganisms. Our findings highlight the need to integrate EDOM characteristics into effluent risk assessments to improve WWTP discharge standards.