Search Results (563)

Antimicrobial resistant (AMR) infections are a persistent public health issue causing excess death and economic impacts globally. Because AMR in clinical settings is often acquired from nonpathogenic bacteria that surround us, environmental surveillance must be better characterized. It has been well established that metals can co-select for bacterial AMR. Furthermore, recent studies have shown that compromised microbial community diversity may lead to community invasion by antibiotic resistance genes (ARGs). Widespread legacy mining has led to acid mine drainage and metal contamination of waterways and sediments throughout the western United States, potentially compromising microbial community diversity while simultaneously selecting for AMR bacteria. Our study objectives were to survey metal contaminated sediments from the Bonita Peak Mining District (BPMD) in southwestern Colorado, USA, compared to sites downstream in Durango, CO for bacterial and ARG diversity. Sediment bacteria were characterized using 16S rRNA Ilumina and metagenomic sequencing. We found that overall, bacterial diversity was lower in metal-contaminated, acidic sites (p = 0.04). Metagenomic sequencing revealed 31 different ARGs, with those encoding for efflux pumps (mex and spe gene families) substantially more prevalent in the BPMD sites, elucidating a specific AMR marker fingerprint from the high metal concentration sediments. Raising awareness and providing antimicrobial tracking techniques to resource limited communities could help provide information needed for better antibiotic use recommendations and environmental monitoring. Full article

Zinc (Zn), a ubiquitous environmental transition metal primarily existing as Zinc ions (Zn²⁺), plays a critical role in various biological processes. Its extensive application in agriculture, industry, and healthcare has led to significant environmental contamination. However, the mechanistic contribution of Zn²⁺ to bacterial antibiotic resistance and virulence remains insufficiently understood. This review explores the sources, cycling, and environmental accumulation of Zn²⁺ in a One Health context, emphasizing their impact on bacterial antibiotic resistance and virulence. Zn²⁺ promote bacterial antibiotic resistance by regulating efflux pumps, biofilm formation, expression and transfer of antibiotic resistance genes, as well as synergistic effects with other heavy metals and antibiotics. Meanwhile, Zn²⁺ promote bacterial virulence by regulating quorum sensing, secretion and metal homeostasis systems, as well as oxidative stress response and virulence factor expression. Additionally, it highlights the potential of targeting Zn homeostasis as a strategy to combat environmental antibiotic resistance. Collectively, these findings provide key insights into the mechanisms by which Zn²⁺ regulate bacterial antibiotic resistance and pathogenicity, offering valuable guidance for developing strategies to mitigate the global threat of antibiotic resistance. Full article

The microbial ecology of acid mine drainage (AMD) systems in Armenia, with a long mining history, remains unexplored. This study aimed to characterize the microbial diversity and functional potential of AMD in the Syunik region and to isolate novel microorganisms with biotechnological value. A comprehensive analysis of the microbial communities’ structure of Kavart abandoned, Kapan exploring mines effluent, and Artsvanik tailing was conducted. Metagenomics revealed bacterial-dominated communities, comprising Pseudomonadota (previously “Proteobacteria”) (68–72%), with site-specific variations in genus abundance. A high abundance and diversity of metal resistance genes (MRGs), particularly for copper and arsenic, were identified. Carbohydrate-active enzyme (CAZy) analysis showed a dominance of GT2 and GT4 genes, suggesting a high potential for extracellular polymeric substances (EPS) production and biofilm formation. A novel strain of iron-oxidizing bacteria Arm-12 was isolated that shares only ~90% similarity with known Leptospirillum type species, indicating it may represent a new genus without culturable representatives. The strain exhibits enhanced copper extraction from concentrate. This study provides the first metagenomic insights into Armenian AMD systems and tailing, revealing a unique community rich in metal resistance and biofilm-forming genes. The isolation of a novel highly effective iron-oxidizer Arm-12 highlights the potential of AMD environments as a source of novel taxa with significant applications in biomining and bioremediation processes. Full article

Mitigation of abiotic stress of crops is currently one of the primary issues for modern agriculture to secure food supply. On that point, it is acknowledged that climate change is leading to an increase in temperature and solar radiation, while also contributing to prolonged drought events. In contrast, saline soil and heavy metal pollution have been globally problematic, affecting a large part of crops. In this review, we have provided an overview of the eco-physiological and molecular aspects of zinc oxide nanoparticles (ZnO-NPs) as a novel technology for alleviating abiotic stress in plants. It is reported that the presence of ZnO-NPs has positive benefits in physiological processes, such as photosynthetic efficiency, osmotic regulation, ionic homeostasis, and the activation of antioxidant defense systems through gene modifications and the regulation of genes that are regulated under stress conditions. These are positive results for yields, nutrition, and resistance levels in cereals, legumes, and horticultural crops. Furthermore, essential details are reported, suggesting that the addition of ZnO-NPs to crops may be involved in regulating plant metabolism. Nonetheless, we recognize that this technology poses significant challenges for validation on a large scale, particularly in uncontrolled environments. Full article

With increasing industrialization, hexavalent chromium (Cr(VI)) is used in various metal smelting and other industries, which, in turn, causes hexavalent chromium pollution. This study aimed to investigate the characteristics of isolated Bacillus subtilis (B. subtilis) from high-Cr(VI) soils and to evaluate its safety. Genomic and transcriptomic analyses were performed to explore its Cr(VI) response mechanisms, and a mouse model (24 mice) was established to evaluate the safety of the bacterium at different concentrations. Key genetic findings showed that Cr(VI) exposure significantly up-regulated the Spx gene and down-regulated the CtsR gene—two critical transcriptional regulators involved in stress response and development that mediate Cr(VI) tolerance. Pathway analysis revealed that ribosome RNA, redox balance, protein biosynthesis, metabolism, and cysteine biosynthesis play a significant role in bacterial Cr(VI) resistance. In the in vivo experiment, it was observed that the small intestine (SI), liver, and spleen of the mice remained normal without any injuries. Different levels of the F3 isolate demonstrated the ability to resist colonization by digestive juices, as observed in the SI slides. Consequently, B. subtilis can endure high levels of Cr(VI) by regulating redox process genes, which makes it a potential candidate for further research in selecting safe, tolerant, and bio-remedial isolates for Cr(VI) treatment. Full article

Long-standing and chronic soil pollution in the Polar Regions is the most persistent. Simultaneous contamination with petroleum products and heavy metals puts additional load on the soil microbial community. The purpose of this work was to determine the composition of prokaryotes in the soils of Mount Kaskama with long-standing contamination with petroleum products and heavy metals (Murmansk region, Russia) and outside this zone and the potential ability of bacteria to participate in the self-purification of these soils. Using high-throughput sequencing of 16S rRNA gene V3–V4 fragments, an increase in the proportion of bacteria of the phyla Pseudomonadota, Verrucomicrobiota, Cyanobacteriota, and Bacillota was shown with an increase in soil contamination. Bacteria of the genera Bacillus, Caballeronia, Cytobacillus, Paenibacillus, Paraburkholderia, Pseudomonas, and Rhodanobacter were isolated from soil samples. Bacteria of the genus Paenibacillus capable of hydrocarbon oxidation and iron reduction were isolated from the subsurface contaminated layers. Under aerobic conditions, Fe(II) oxidation by bacteria of the genus Pseudomonas and biodegradation of hydrocarbons by isolated bacteria are possible. The isolated strains grew at low temperatures, used diesel fuel components, and were resistant to Cu(II), Ni(II), and Pb(II). The data obtained indicates the adaptation of bacterial communities to environmental conditions and the ability to participate in the process of soil self-healing. Full article

The extensive and often inappropriate use of antibiotics has led to the rapid emergence and spread of antibiotic resistance, reducing their effectiveness against pathogenic microorganisms. Fosfomycin has become an increasingly important therapeutic option in both human and veterinary medicine, particularly when other antibiotics fail. This review summarises current knowledge on the occurrence of fosfomycin resistance and evaluates the role of agricultural practices in its dissemination. Multiple microbial resistance mechanisms have been identified, including genes from the fosA, fosB, and fosC families, and new determinants continue to be reported. Agriculture contributes to the environmental spread of resistance through the use of antibiotics in food-producing animals, the exchange of resistant microorganisms between humans and animals, and the application of manure as fertiliser. Fosfomycin resistance genes have been detected in livestock such as pigs, chickens, pigeons, and cows, as well as in vegetables. Their presence in soil is influenced by fertilisation, nitrogen levels, microplastics, heavy metals, and pesticide application. Additionally, climate warming may facilitate the broader dissemination of fosfomycin resistance. Despite increasing evidence, current understanding remains limited. Further research is needed to elucidate the mechanisms driving the spread of fosfomycin resistance in agricultural environments and to develop effective monitoring strategies. Full article

This study examines the occurrence of bacteria resistant to antibiotics and heavy metals in Terra Nova Bay, a coastal area of the Ross Sea in Antarctica that is increasingly recognised as vulnerable to human influence. During the 37th Italian Antarctic Expedition (2021–2022), researchers collected seawater, sediment, and fish samples from the notothenioid species Trematomus bernacchii to evaluate microbial resistance in an environment once considered largely pristine. Fifty heterotrophic bacterial isolates were obtained and tested against twenty-eight antibiotics, revealing a notable presence of multidrug resistance. These multidrug-resistant isolates were then assessed for their tolerance to eight heavy metal salts to understand whether resistance traits extended beyond antimicrobials. Twelve isolates showing resistance to both antibiotics and metals were selected for further genetic screening, targeting key resistance genes linked to tetracycline, vancomycin, sulphonamides, and other antimicrobial classes. The detection of multiple resistance genes in genera such as Pseudomonas, Pseudoalteromonas, and Psychrobacter indicates that both natural selective pressures and local, human-related contamination may be shaping resistance patterns in this region. Overall, the study demonstrates that even remote Antarctic marine ecosystems can host bacteria with complex resistance profiles. While these ecosystems are largely isolated, human activities such as scientific research, tourism, and the introduction of pollutants may contribute to the dissemination of antibiotic resistance genes, raising important ecological and potential public health considerations regarding the spread of resistance in polar environments. Full article

Although cancer biology has advanced considerably, the impact of environmental toxins on carcinogenesis remains underrecognized and scattered across disciplines. Evidence increasingly shows that chronic exposure to a broad range of toxins—including persistent organic pollutants, heavy metals, pesticides, phthalates, microplastics, and fine particulate matter (PM2.5), which significantly contributes to cancer initiation, progression, and treatment resistance. This review synthesizes mechanistic, molecular, and epidemiological findings from 2015 to 2025, identified through systematic searches of PubMed, Scopus, Web of Science, and MeSH. Key pathways include oxidative stress-mediated DNA damage, epigenetic reprogramming (DNA methylation, histone modifications, miRNA dysregulation), hormone receptor modulation, chronic inflammation, immune evasion, and tumor microenvironment remodeling. Case studies of benzene, arsenic, aflatoxins, pesticides, and microplastics detail exposure routes, molecular targets, and associated cancers, highlighting significant public health risks. Ongoing debates persist regarding safe exposure thresholds, latency periods, and the effects of mixed toxin exposures. The review also highlights recent innovations in environmental oncology, including AI-based predictive models, CRISPR screens for susceptibility genes, organoid/3D models, green chemistry interventions, and real-time exposure monitoring, which provide mechanistic insight and inform early detection and personalized prevention strategies. Additionally, regional data gaps, particularly in low- and middle-income countries, indicate the need for stronger interdisciplinary collaboration. By integrating molecular mechanisms, epidemiology, and technological advances, this review offers a comprehensive framework for understanding toxin-induced carcinogenesis and guiding future research, public health policy, and preventive strategies. Full article

Powdery mildew poses a persistent threat to global vegetable and fruit production, particularly affecting leafy crops such as lettuce, spinach, and cucurbits. Conventional control strategies including chemical fungicides, biological agents, and resistant cultivars face limitations due to resistance development, environmental toxicity, and inconsistent field efficacy. This review explores the emerging role of nanotechnology, specifically nanoparticles (NPs) and nanosuspensions (NSs), in managing powdery mildew. Metallic nanoparticles and non-metallic variants demonstrate potent antifungal activity through mechanisms such as membrane disruption, reactive oxygen species (ROS) generation, and gene regulation. Encapsulated nano-fungicides and sprayable essential oils represent potential application methods that could enhance delivery precision and activate plant defense mechanisms against powdery mildew. Integrating the application of nanoparticles and nanosuspensions with smart and digital delivery systems could be a promising strategy for managing powdery mildew infestation in fruits and vegetables. Despite their potential, challenges including ecotoxicity, formulation stability, scalability, and regulatory gaps must be addressed. This review underscores the need for interdisciplinary research to advance safe, effective, and sustainable nano-enabled solutions for powdery mildew control. Full article

Lead and zinc pollution is a prevalent issue in agricultural soils surrounding lead and zinc mines, posing a serious risk to crop growth and soil health. Heavy metal-resistant, plant growth-promoting bacteria (PGPB) capable of supporting plant development under high metal exposure have significant potential for mitigating these deleterious effects. Here we isolated and identified the Pb- and Zn-resistant and plant growth-promoting bacterial strain Serratia ureilytica T6 based on 16S rRNA and average nucleotide identity (ANI) analysis. Furthermore, 14 strains (T1–T14) from a rice paddy soil irrigated by Pb-Zn mine effluent were isolated and identified, and their phytopromoting characteristics were determined. Genome analysis of S. ureilytica T6 showed a genome size of 5,102,941 bp, with G + C content of 59.74%. A total of 4822 genes were annotated by RAST, among which 15 genes were putatively associated with Pb-Zn resistance. The genome of S. ureilytica T6 was found to possess multiple genes associated with probiotic properties by a comparative analysis of KEGG, GO, and COG databases. Several taxonomic identifications of S. ureilytica T6 revealed that strain T6 is Gram-negative, facultative anaerobic and motile. The pH growth range of S. ureilytica T6 was between 4.00 and 9.50; temperature growth range was 4–37 °C; NaCl tolerance was 0–9%. S. ureilytica T6 displayed a high tolerance to a variety of heavy metals, with minimum inhibitory concentrations of 1.5 and 9 mmol·L⁻¹ for Pb and Zn. S. ureilytica T6 can utilize a variety of carbon sources and nitrogen sources. T6 has the ability to produce indole-3-acetic acid (IAA), siderophore, and phosphorus and potassium solubilization, and it was initially judged that strain T6 has the potential for plant growth-promoting ability. Different plant growth-promoting effects of T6 inoculations were observed in improving rice biomass, plant height, etc. We observed that with increasing Pb and Zn stress, SOD activity first increased and then decreased, while POD and CAT activities gradually decreased. The addition of S. ureilytica T6 significantly enhanced the activities of SOD, POD, and CAT in rice seedlings under low to moderate Pb and Zn stress but had no significant effect under high concentrations (150 mg·L⁻¹) of Pb or Zn. In addition, S. ureilytica T6 has the potential to be used as a phytoremediation tool. Full article

Karstic regions are globally distributed, and the soil-forming parent rocks and their weathering process primarily cause elevated geochemical heavy metal (HM) accumulation in karst soils. However, the patterns of HMs, the genes related to resistance, and their interactions in karstic soils developed from different parent materials remain unexplored. In this study, 36 field karst soil samples originating from two parent materials were collected, including 19 samples from the residues of the weathering and leaching of carbonate rocks (Car) and 17 samples from Quaternary sediments (Qua). In the Car soils, the levels of As, Cd, Cr, Zn, Cu, Ni, and Pb exceeded the risk screening values for soil contamination of agricultural land set by the Chinese standard GB15618-2018 by 100%, 100%, 94.11%, 64.71%, 64.71%, 47.06%, and 41.18%, respectively, while only 11.76% of As in Qua soils exceeded the risk screening values. The proportion of metal resistance genes (MRGs) and antibiotic resistance genes (ARGs) in Car soils was significantly higher than that in Qua soils. However, HM content had a significantly positive correlation with Nemerow integrated pollution index (NIPI), individual HM-related genes, MRGs, ARGs, and mobile genetic elements (MGEs) in Qua soils, respectively. Although the corresponding correlation was positive in the Car soils, it was not statistically significant. Results demonstrated that microbial activity was more crucial for the accumulation of HMs in Qua soils compared with Car soils. Meanwhile, our in-depth research also provides new perspectives to establish a more rational ecological assessment for the elevated HMs by identifying applicable and valid biomarkers from functional genes, which is vital in contamination monitoring, prevention, and standard establishment in agricultural soils of karst regions. Full article

Cadmium (Cd), a toxic and mobile heavy metal, poses significant risks to agricultural systems due to industrial pollution. Tea plants (Camellia sinensis L.) efficiently absorb and accumulate Cd from soil, leading to contamination in leaves. Chronic consumption of Cd-laden tea can cause severe health issues, including neurological, reproductive, and immunological disorders, as well as increased cancer risk. Despite growing concerns, the molecular mechanisms of Cd stress response in tea plants remain poorly understood. Current research highlights key physiological adaptations, including activation of antioxidant defenses and modulation of secondary metabolite pathways, which influence tea quality. Cd disrupts photosynthesis, induces oxidative stress, and alters the biosynthesis of flavor-related compounds. Several critical genes involved in Cd transport (e.g., CsNRAMP5, CsHMA3, CsZIP1), sequestration (CsPCS1), and stress regulation (CsMYB73, CsWRKY53, CsbHLH001) have been identified, offering insights into molecular responses. This review systematically examines Cd dynamics in the soil-tea plant system, its effects on growth, photosynthesis, and quality, and the physiological and biochemical mechanisms underlying Cd tolerance. By consolidating recent findings on Cd-responsive genes and regulatory pathways, this study provides a theoretical foundation for breeding Cd-resistant tea varieties and ensuring production safety. Furthermore, it identifies future research directions, emphasizing the need for deeper mechanistic insights and practical mitigation strategies. These advancements will contribute to safer tea consumption and sustainable cultivation practices in Cd-contaminated regions. Full article

The improper use of antibiotics accelerates the emergence of resistance via environmental selection pressures, jeopardizing public health and ecosystems by promoting the worldwide dissemination of antibiotic resistance genes (ARGs). Reservoirs, as crucial water supplies, have been recognized as primary reservoirs of ARGs, particularly those that originate from the Yellow River, necessitating further investigation. This study analyzed 9 ARGs, 3 mobile genetic elements (MGEs), 16 antibiotics, and 10 heavy metals in water/sediments from three reservoirs originating from the Yellow River in Henan Province, China. The findings indicated that antibiotic concentrations in water exceeded those in sediment, with quinolones detected at 100% frequency (5.47–116.03 ng/L) and enrofloxacin predominating (3.36–107.71 ng/L). Redundancy analysis revealed that MGEs exert greater control over ARG dissemination than antibiotics, with intI1 showing strong positive correlations with sul1 (p < 0.05). Conversely, heavy metals (Zn, As, Cd) suppress ARG proliferation through negative selection pressures. A network study indicated Mycobacterium, Pseudarthrobacter, and Massilia as critical hosts for ermB, tetA, and qnrA, respectively. Of the three reservoirs, Jian’gang Reservoir, driven by synergistic effects of unique microbial ecology, water self-purification capacity, and flow dynamics, exhibited the best removal effectiveness of ARGs from input to outflow, with 71.75% in the water and 97.91% in the sediment. These findings provide critical insights into the prevalence, migration, and self-purification processes of ARGs in reservoirs originating from the Yellow River, integrating environmental factors and microbial data to clarify the complex dynamics affecting ARG behavior and inform targeted pollution control strategies. Full article

Growing evidence highlights the role of heavy metals in driving the co-selection of an-tibiotic resistance genes (ARGs), and the human oral cavity is an important reservoir of ARGs. This cross-sectional study investigated the effects of heavy metal exposure on human oral microbiota and ARGs, collecting buccal mucosal and blood samples from residents in a heavy metal-contaminated area (Baiyin City) and a non-contaminated area (Yuzhong County, Lanzhou City). The results showed heavy metal exposure is associated with altered alpha and beta diversity of bacteria and ARGs in human oral cavities, with bacterial compositional shifts being the main factor in ARG variation. Metagenomic analysis revealed heavy metal exposure is linked to modifying the interactions in the bacterial community and between ARGs and metal resistance genes (MRGs), shown by simplified topological structures in bacterial and resistome networks, along with enhanced positive correlations among nodes. Neisseria, Haemophilus, Morococcus, Streptococcus, Staphylococcus, and Mycobacteroides as potential hosts for resistance genes in human oral cavity. Furthermore, blood metal quantification revealed distinct associations with resistance patterns. This study demonstrates significant associations between environmental heavy metal exposure and the oral resistome and emphasizes the role of bacterial community composition. Full article