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678800.9667Release and Constancy of an Antibiotic Resistance Gene in Seawater under Grazing Stress by Ciliates and Heterotrophic Nanoflagellates. Extracellular DNA (exDNA) is released from bacterial cells through various processes. The antibiotic resistance genes (ARGs) coded on exDNA may be horizontally transferred among bacterial communities by natural transformation. We quantitated the released/leaked tetracycline resistance gene, tet(M) over time under grazing stress by ciliates and heterotrophic nanoflagellates (HNFs), and found that extracellular tet(M) (ex-tetM) increased with bacterial grazing. Separate microcosms containing tet(M)-possessing bacteria with ciliates or HNFs were prepared. The copy number of ex-tetM in seawater in the ciliate microcosm rapidly increased until 3 d after the incubation, whereas that in the HNF microcosm showed a slower increase until 20 d. The copy number of ex-tetM was stable in both cases throughout the incubation period, suggesting that extracellular ARGs are preserved in the environment, even in the presence of grazers. Additionally, ARGs in bacterial cells were constant in the presence of grazers. These results suggest that ARGs are not rapidly extinguished in a marine environment under grazing stress.201728592722
678710.9625Impact of chlorine disinfection on intracellular and extracellular antimicrobial resistance genes in wastewater treatment and water reclamation. Wastewater treatment plants and water reclamation facilities are reservoirs of antimicrobial resistance genes (ARGs). These ARGs are not limited solely to intracellular DNA (inARGs) but include extracellular DNA (exARGs) present in wastewater. The release of exARGs from cells can be exacerbated by treatment processes, including chlorine disinfection, which disrupts bacterial cells. Given the potential for exARGs to drive horizontal gene transfer and contribute to the proliferation of antimicrobial resistance, it is imperative to recognize these fractions as emerging environmental pollutants. In this study, we conducted a comprehensive year-long assessment of both inARGs and exARGs, further differentiating between dissolved exARGs (Dis_exARGs) and exARGs adsorbed onto particulate matter (Ads_exARGs), within a full-scale wastewater treatment and water reclamation facility. The results revealed that Ads_exARGs comprised up to 30 % of the total ARGs in raw sewage with high biomass content. Generally, treatments at low and high doses of chlorine increased the abundance of Dis_exARGs and Ads_exARGs. The fate of ARG levels that varied depending on the type of ARGs suggested variations in the susceptibility of the host bacteria to chlorination. Moreover, co-occurrence of several potential opportunistic pathogenic bacteria and ARGs were observed. Therefore, we propose higher doses of chlorination as a prerequisite for the effective removal of inARGs and exARGs.202439067603
843120.9621A quaternary ammonium salt grafted tannin-based flocculant boosts the conjugative transfer of plasmid-born antibiotic resistance genes: The nonnegligible side of their flocculation-sterilization properties. This study developed dual-function tannin-based flocculants, namely tannin-graft-acrylamide-diallyl dimethyl ammonium chloride (TGCC-A/TGCC-C), endowed with enhanced flocculation-sterilization properties. The impacts of these flocculants on proliferation and transformation of antibiotic resistance genes (ARGs) among bacteria during the flocculation-deposition process were examined. TGCC-A/TGCC-C exhibited remarkable flocculation capacities towards both Escherichia coli and Staphylococcus aureus, encompassing a logarithmic range of initial cell density (10(8)-10(9) CFU/mL) and a broad pH spectrum (pH 2-11). The grafted quaternary ammonium salt groups played pivotal parts in flocculation through charge neutralization and bridging mechanisms, concurrently contributing to sterilization by disrupting cellular membranes. The correlation between flocculation and sterilization entails a sequential progression, where an excess of TGCC, initially employed for flocculation, is subsequently consumed for sterilization purposes. The frequencies of ARGs conjugative transfer were enhanced in bacterial flocs across all TGCC treatments, stemming from augmented bacterial aggregation and cell membrane permeability, elicited stress response, and up-regulated genes encoding plasmid transfer. These findings underscore the indispensable role of flocculation-sterilization effects in mediating the propagation of ARGs, consequently providing substantial support for the scientific evaluation of the environmental risks associated with flocculants in the context of ARGs dissemination during the treatment of raw water featuring high bacterial density.202337619725
794030.9613Microplastics affect the ammonia oxidation performance of aerobic granular sludge and enrich the intracellular and extracellular antibiotic resistance genes. Microplastics (MPs) and antibiotic resistance genes (ARGs), as emerging pollutants, are frequently detected in wastewater treatment plants, and their threats to the environment have received extensive attentions. However, the effects of MPs on the nitrification of aerobic granular sludge (AGS) and the spread patterns of intracellular and extracellular ARGs (iARGs and eARGs) in AGS were still unknown. In this study, the responses of AGS to the exposure of 1, 10 and 100 mg/L of typical MPs (polyvinyl chloride (PVC), polyamide (PA), polystyrene (PS) and polyethylene (PE)) and tetracycline were focused on in 3 L nitrifying sequencing batch reactors. 10 mg/L MPs decreased the nitrification function, but nitrification could recover. Furthermore, MPs inhibited ammonia-oxidizing bacteria and enriched nitrite-oxidizing bacteria, leading partial nitrification to losing stability. PVC, PA and PS stimulated the secretion of extracellular polymeric substances and reactive oxygen species. PE had less negative effect on AGS than PVC, PA and PS. The abundances of iARGs and eARGs (tetW, tetE and intI1) increased significantly and the intracellular and extracellular microbial communities obviously shifted in AGS system under MPs stress. Potential pathogenic bacteria might be the common hosts of iARGs and eARGs in AGS system and were enriched in AGS and MPs biofilms.202133387747
848640.9612Multidrug-resistant plasmid modulates ammonia oxidation efficiency in Nitrosomonas europaea through cyclic di-guanylate and acyl-homoserine lactones pathways. Antibiotic resistance genes present a major public health challenge and have potential implications for global biogeochemical cycles. However, their impacts on biological nitrogen removal systems remain poorly understood. In the ammonia-oxidizing bacteria Nitrosomonas europaea ATCC 19718 harboring the multidrug-resistant plasmid RP4, a significant decrease in ammonia oxidation efficiency was observed, accompanied by markedly elevated levels of cyclic di-guanylate (c-di-GMP) and acyl-homoserine lactones (AHLs), compared to plasmid-free controls. The results demonstrated that c-di-GMP facilitates the secretion of AHLs, while elevated levels of AHLs inhibit the ammonia oxidation efficiency of Nitrosomonas europaea ATCC 19718. These results revealed that RP4 plasmid significantly impaired ammonia oxidation efficiency through the c-di-GMP and AHLs pathways. Our findings indicate that the multidrug-resistant plasmid RP4 adversely affects the nitrogen metabolism of ammonia-oxidizing bacteria, potentially disrupting the nitrogen biogeochemical cycle and posing substantial ecological and environmental risks.202640945801
792750.9612Different microplastics distinctively enriched the antibiotic resistance genes in anaerobic sludge digestion through shifting specific hosts and promoting horizontal gene flow. Both microplastics (MPs) and antibiotic resistance genes (ARGs) are intensively detected in waste activated sludge (WAS). However, the distinctive impacts of different MPs on ARGs emergence, dissemination, and its potential mechanisms remain unclear. In this study, long-term semi-continuous digesters were performed to examine the profiles of ARGs and antibiotic-resistant bacteria (ARB) in response to two different typical MPs (polyethylene (PE) and polyvinyl chloride (PVC)) in anaerobic sludge digestion. Metagenomic results show that PE- and PVC-MPs increase ARGs abundance by 14.8% and 23.6% in digester, respectively. ARB are also enriched by PE- and PVC-MPs, Acinetobacter sp. and Salmonella sp. are the dominant ARB. Further exploration reveals that PVC-MPs stimulates the acquisition of ARGs by human pathogen bacteria (HPB) and functional microorganisms (FMs), but PE-MPs doesn't. Network analysis shows that more ARGs tend to co-occur with HBP and FMs after MPs exposure, and more importantly, new bacteria are observed to acquire ARGs possibly via horizontal gene flow (HGF) in MPs-stressed digester. The genes involved in the HGF process, including reactive oxygen species (ROS) production, cell membrane permeability, extracellular polymeric substances (EPS) secretion, and ATP synthesis, are also enhanced by MPs, thereby attributing to the promoted ARGs dissemination. These findings offer advanced insights into the distinctive contribution of MPs to fate, host, dissemination of ARGs in anaerobic sludge digestion.202336423550
792660.9610Microplastics Exacerbated Conjugative Transfer of Antibiotic Resistance Genes during Ultraviolet Disinfection: Highlighting Difference between Conventional and Biodegradable Ones. Microplastics (MPs) have been confirmed as a hotspot for antibiotic resistance genes (ARGs) in wastewater. However, the impact of MPs on the transfer of ARGs in wastewater treatment remains unclear. This study investigated the roles and mechanisms of conventional (polystyrene, PS) and biodegradable (polylactic acid, PLA) MPs in the conjugative transfer of ARGs during ultraviolet disinfection. The results showed that MPs significantly facilitated the conjugative transfer of ARGs compared with individual ultraviolet disinfection, and PSMPs exhibited higher facilitation than PLAMPs. The facilitation effects were attributed to light shielding and the production of reactive oxygen species (ROS) and nanoplastics from ultraviolet irradiation of MPs. The light shielding of MPs protected the bacteria and ARGs from ultraviolet inactivation. More importantly, ROS and nanoplastics generated from irradiated MPs induced intracellular oxidative stress on bacteria and further increased the cell membrane permeability and intercellular contact, ultimately enhancing the ARG exchange. The greater fragmentation of PSMPs than PLAMPs resulted in a higher intracellular oxidative stress and a stronger enhancement. This study highlights the concerns of conventional and biodegradable MPs associated with the transfer of ARGs during wastewater treatment, which provides new insights into the combined risks of MPs and ARGs in the environment.202539723446
679370.9610Interplays between cyanobacterial blooms and antibiotic resistance genes. Cyanobacterial harmful algal blooms (cyanoHABs), which are a form of microbial dysbiosis in freshwater environments, are an emerging environmental and public health concern. Additionally, the freshwater environment serves as a reservoir of antibiotic resistance genes (ARGs), which pose a risk of transmission during microbial dysbiosis, such as cyanoHABs. However, the interactions between potential synergistic pollutants, cyanoHABs, and ARGs remain poorly understood. During cyanoHABs, Microcystis and high microcystin levels were dominant in all the nine regions of the river sampled. The resistome, mobilome, and microbiome were interrelated and linked to the physicochemical properties of freshwater. Planktothrix and Pseudanabaena competed with Actinobacteriota and Proteobacteria during cyanoHABs. Forty two ARG carriers were identified, most of which belonged to Actinobacteriota and Proteobacteria. ARG carriers showed a strong correlation with ARGs density, which decreased with the severity of cyanoHAB. Although ARGs decreased due to a reduction of ARG carriers during cyanoHABs, mobile gene elements (MGEs) and virulence factors (VFs) genes increased. We explored the relationship between cyanoHABs and ARGs for potential synergistic interaction. Our findings demonstrated that cyanobacteria compete with freshwater commensal bacteria such as Actinobacteriota and Proteobacteria, which carry ARGs in freshwater, resulting in a reduction of ARGs levels. Moreover, cyanoHABs generate biotic and abiotic stress in the freshwater microbiome, which may lead to an increase in MGEs and VFs. Exploration of the intricate interplays between microbiome, resistome, mobilome, and pathobiome during cyanoHABs not only revealed that the mechanisms underlying the dynamics of microbial dysbiosis but also emphasizes the need to prioritize the prevention of microbial dysbiosis in the risk management of ARGs.202337897871
849280.9610Promotion effects and mechanisms of molybdenum disulfide on the propagation of antibiotic resistance genes in soil. The rapid development of nanotechnology has aroused considerable attentions toward understanding the effects of engineered nanomaterials (ENMs) on the propagation of antibiotic resistance. Molybdenum disulfide (MoS(2)) is an extensively used ENM and poses potential risks associated with environmental exposure; nevertheless, the role of MoS(2) toward antibiotic resistance genes (ARGs) transfer remains largely unknown. Herein, it was discovered that MoS(2) nanosheets accelerated the horizontal transfer of RP4 plasmid across Escherichia coli in a dose-dependent manner (0.5-10 mg/L), with the maximum transfer frequency 2.07-fold higher than that of the control. Integration of physiological, transcriptomics, and metabolomics analyses demonstrated that SOS response in bacteria was activated by MoS(2) due to the elevation of oxidative damage, accompanied by cell membrane permeabilization. MoS(2) promoted bacterial adhesion and intercellular contact via stimulating the secretion of extracellular polysaccharides. The ATP levels were maximally increased by 305.7 % upon exposure to MoS(2), and the expression of plasmid transfer genes was up-regulated, contributing to the accelerated plasmid conjugation and increased ARG abundance in soil. Our findings highlight the roles of emerging ENMs (e.g., MoS(2)) in ARGs dissemination, which is significant for the safe applications and risk management of ENMs under the development scenarios of nanotechnology.202337062264
793590.9610Removal of antibiotic resistance genes by Cl(2)-UV process: Direct UV damage outweighs free radicals in effectiveness. Antibiotic resistance genes (ARGs) pose significant environmental health problems and have become a major global concern. This study investigated the efficacy and mechanism of the Cl(2)-UV process (chlorine followed by UV irradiation) for removing ARGs in various forms. The Cl(2)-UV process caused irreversible damage to nearly all ARB at typical disinfectant dosages. In solutions containing only extracellular ARGs (eARGs), the Cl₂-UV process achieved over 99.0 % degradation of eARGs. When both eARGs and intracellular ARGs (iARGs) were present, the process reached a 97.2 % removal rate for iARGs. While the abundance of eARGs initially increased due to the release of iARGs from lysed cells during pre-chlorination, subsequent UV irradiation rapidly degraded the released eARGs, restoring their abundance to near-initial levels by the end of the Cl₂-UV process. Analysis of the roles in degrading eARGs and iARGs during the Cl(2)-UV process revealed that UV, rather than free radicals, was the dominant factor causing ARG damage. Pre-chlorination enhanced direct UV damage to eARGs and iARGs by altering plasmid conformation and promoting efficient damage to high UV-absorbing cellular components. Furthermore, no further natural transformation of residual ARGs occurred following the Cl(2)-UV treatment. This study demonstrated strong evidence for the effectiveness of the Cl(2)-UV process in controlling antibiotic resistance.202540048777
7939100.9607Metagenomic insights into the distribution, mobility, and hosts of extracellular antibiotic resistance genes in activated sludge under starvation stress. Extracellular antibiotic resistance genes (eARGs) are important emerging environmental pollutants in wastewater treatment plants (WWTPs). Nutritional substrate deficiency (i.e., starvation) frequently occurs in WWTPs owing to annual maintenance, water quality fluctuation, and sludge storage; and it can greatly alter the antibiotic resistance and extracellular DNA content of bacteria. However, the fate and corresponding transmission risk of eARGs in activated sludge under starvation stress remain largely unknown. Herein, we used metagenomic sequencing to explore the effects of starvation scenarios (carbon, nitrogen, and/or phosphorus deficiency) and environmental conditions (alternating anaerobic-aerobic, anaerobic, anoxic, and aerobic) on the distribution, mobility, and hosts of eARGs in activated sludge. The results showed that 30 days of starvation reduced the absolute abundances of eARGs by 40.9%-88.2%, but high-risk dual and multidrug resistance genes persisted. Starvation, particularly the simultaneous lack of carbon, nitrogen, and phosphorus under aerobic conditions, effectively alleviated eARGs by reducing the abundance of extracellular mobile genetic elements (eMGEs). Starvation also altered the profile of bacterial hosts of eARGs and the bacterial community composition, the latter of which had an indirect positive effect on eARGs via changing eMGEs. Our findings shed light on the response patterns and mechanisms of eARGs in activated sludge under starvation conditions and highlight starvation as a potential strategy to mitigate the risk of previously neglected eARGs in WWTPs.202337060877
8357110.9606Identification of novel Legionella genes required for endosymbiosis in Paramecium based on comparative genome analysis with Holospora spp. The relationship between Legionella and protist hosts has a huge impact when considering the infectious risk in humans because it facilitates the long-term replication and survival of Legionella in the environment. The ciliate Paramecium is considered to be a protist host for Legionella in natural environments, but the details of their endosymbiosis are largely unknown. In this study, we determined candidate Legionella pneumophila genes that are likely to be involved in the establishment of endosymbiosis in Paramecium caudatum by comparing the genomes of Legionella spp. and Holospora spp. that are obligate endosymbiotic bacteria in Paramecium spp. Among the candidate genes, each single deletion mutant for five genes (lpg0492, lpg0522, lpg0523, lpg2141 and lpg2398) failed to establish endosymbiosis in P. caudatum despite showing intracellular growth in human macrophages. The mutants exhibited no characteristic changes in terms of their morphology, multiplication rate or capacity for modulating the phagosomes in which they were contained, but their resistance to lysozyme decreased significantly. This study provides insights into novel factors required by L. pneumophila for endosymbiosis in P. caudatum, and suggests that endosymbiotic organisms within conspecific hosts may have shared genes related to effective endosymbiosis establishment.201830124811
6934120.9606Impact of protist predation on bacterial community traits in river sediments. Sediment-associated microbial communities are pivotal in driving biogeochemical processes and serve as key indicators of ecosystem health and function. However, the ecological impact of protist predation on these microbial communities remains poorly understood. Here, sediment microcosms were established with varying concentrations of indigenous protists. Results revealed that protist predation exerted strong and differential effects on the bacterial community composition, functional capabilities, and antibiotic resistance profiles. Higher levels of protist predation pressure increased bacterial alpha diversity and relative abundance of genera associated with carbon and nitrogen cycling, such as Fusibacter, Methyloversatilis, Azospirillum, and Holophaga. KEGG analysis indicated that protist predation stimulated microbial processes related to the carbon, nitrogen, and sulfur cycles. Notably, the relative abundance and associated health risks of antibiotic resistance genes (ARGs), virulence factor genes (VFGs), and mobile genetic elements (MGEs) were affected by predation pressure. Medium protist predation pressure increased the relative abundance and potential risks associated with ARGs, whereas high protist concentrations led to a reduction in both, likely due to a decrease in the relative abundance of ARG-hosting pathogenic bacteria such as Pseudomonas, Acinetobacter, and Aeromonas. These findings provide comprehensive insights into the dynamics of bacterial communities under protist predation in river sediment ecosystems.202540885182
7893130.9605Removal of ofloxacin and inhibition of antibiotic resistance gene spread during the aerobic biofilm treatment of rural domestic sewage through the micro-nano aeration technology. Micro-nano aeration (MNA) has great potential for emerging contaminant removal. However, the mechanism of antibiotic removal and antibiotic resistance gene (ARG) spread, and the impact of the different aeration conditions remain unclear. This study investigated the adsorption and biodegradation of ofloxacin (OFL) and the spread of ARGs in aerobic biofilm systems under MNA and conventional aeration (CVA) conditions. Results showed that the MNA increased OFL removal by 17.27 %-40.54 % and decreased total ARG abundance by 36.37 %-54.98 %, compared with CVA. MNA-induced biofilm rough morphology, high zeta potential, and reduced extracellular polymeric substance (EPS) secretion enhanced OFL adsorption. High dissolved oxygen and temperature, induced by MNA-enriched aerobic bacteria and their carrying OFL-degrading genes, enhanced OFL biodegradation. MNA inhibited the enrichment of ARG host bacteria, which acquired ARGs possibly via horizontal gene transfer (HGT). Functional profiles involved in the HGT process, including reactive oxygen species production, membrane permeability, mobile genetic elements (MGEs), adenosine triphosphate synthesis, and EPS secretion, were down-regulated by MNA, inhibiting ARG spread. Partial least-squares path modeling revealed that MGEs might be the main factor inhibiting ARG spread. This study provides insights into the mechanisms by which MNA enhances antibiotic removal and inhibits ARG spread in aerobic biofilm systems.202539733752
8529140.9605Investigating and Modeling the Regulation of Extracellular Antibiotic Resistance Gene Bioavailability by Naturally Occurring Nanoparticles. Extracellular antibiotic resistance genes (eARGs) are widespread in the environment and can genetically transform bacteria. This work examined the role of environmentally relevant nanoparticles (NPs) in regulating eARG bioavailability. eARGs extracted from antibiotic-resistant B. subtilis were incubated with nonresistant recipient B. subtilis cells. In the mixture, particle type (either humic acid coated nanoparticles (HASNPs) or their micron-sized counterpart (HASPs)), DNase I concentration, and eARG type were systematically varied. Transformants were counted on selective media. Particles decreased bacterial growth and eARG bioavailability in systems without nuclease. When DNase I was present (≥5 μg/mL), particles increased transformation via chromosomal (but not plasmid-borne) eARGs. HASNPs increased transformation more than HASPs, indicating that the smaller nanoparticle with greater surface area per volume is more effective in increasing eARG bioavailability. These results were also modeled via particle aggregation theory, which represented eARG-bacteria interactions as transport leading to collision, followed by attachment. Using attachment efficiency as a fitting factor, the model predicted transformant concentrations within 35% of experimental data. These results confirm the ability of NPs to increase eARG bioavailability and suggest that particle aggregation theory may be a simplified and suitable framework to broadly predict eARG uptake.202235853206
8741150.9605Acclimation of electroactive biofilms under different operating conditions: comprehensive analysis from architecture, composition, and metabolic activity. Electroactive biofilms (EABs) have aroused wide concern in waste treatment due to their unique capability of extracellular electron transfer with solid materials. The combined effect of different operating conditions on the formation, microbial architecture, composition, and metabolic activity of EABs is still unknown. In this study, the impact of three different factors (anode electrode, substrate concentration, and resistance) on the acclimation and performance of EABs was investigated. The results showed that the shortest start-up time of 127.3 h and highest power density of 0.84 W m(-2) were obtained with carbon brush as electrode, low concentration of substrate (1.0 g L(-1)), and 1000 Ω external resistance (denoted as N1). The EABs under N1 condition also represented strongest redox capacity, lowest internal resistance, and close arrangement of bacteria. Moreover, the EABs cultured under different conditions both showed similar results, with direct electron transfer (DET) dominated from EABs to anode. Microbial community compositions indicated that EABs under N1 condition have lowest diversity and highest abundance of electroactive bacteria (46.68%). Higher substrate concentration (3.0 g L(-1)) promoted the proliferation of some other bacteria without electroactivity, which was adverse to EABs. The metabolic analysis showed the difference of genes related to electron transfer (cytochrome C and pili) and biofilm formation (xap) of EABs under different conditions, which further demonstrated the higher electroactivity of EABs under N1. These results provided a comprehensive understanding of the effect of different operating conditions on EABs including biofilm formation and electrochemical activity.202337749470
8491160.9602Hormesis-like effects of black phosphorus nanosheets on the spread of multiple antibiotic resistance genes. The production scalability and increasing demand for black phosphorus nanosheets (BPNSs) inevitably lead to environmental leakage. Although BPNSs' ecotoxicological effects have been demonstrated, their indirect health risks, such as inducing increased resistance in pathogenic bacteria, are often overlooked. This study explores the influence of BPNSs on the horizontal gene transfer of antibiotic resistance genes (ARGs) facilitated by the RP4 plasmid, which carries multiple resistance genes. The results indicated that BPNSs exhibited concentration-dependent hormesis-like effects on bacterial conjugation gene transfer. Specifically, at sub-inhibitory concentrations (0.0001-1 mg/L), BPNSs promoted both intra- and intergeneric conjugative transfer, demonstrating an initial increase followed by a decline, with transfer rates rising by 1.5-3.1-fold and 1.5-3.3-fold, respectively. BPNSs were found to induce reactive oxygen species (ROS) production, increase malondialdehyde levels, and trigger the SOS response, enhancing plasmid uptake. Additionally, BPNSs increased membrane permeability by forming pores and upregulating outer membrane porins (OMPs) genes. At higher BPNSs concentrations (0.1-1 mg/L), conjugative frequency was inhibited due to the disruption of the cellular antioxidant system and changes in the adsorption process. These findings underscore the influence of BPNSs on the conjugative transfer of ARGs, complementing current knowledge of the biotoxicity and potential ecological risks associated with BPNSs.202539827804
7877170.9602External circuit loading mode regulates anode biofilm electrochemistry and pollutants removal in microbial fuel cells. This study investigated the effects of different external circuit loading mode on pollutants removal and power generation in microbial fuel cells (MFC). The results indicated that MFC exhibited distinct characteristics of higher maximum power density (P(max)) (named MFC-HP) and lower P(max) (named MFC-LP). And the capacitive properties of bioanodes may affect anodic electrochemistry. Reducing external load to align with the internal resistance increased P(max) of MFC-LP by 54.47 %, without no obvious effect on MFC-HP. However, intermittent external resistance loading (IER) mitigated the biotoxic effects of sulfamethoxazole (SMX) (a persistent organic pollutant) on chemical oxygen demand (COD) and NH(4)(+)-N removal and maintained high P(max) (424.33 mW/m(2)) in MFC-HP. Meanwhile, IER mode enriched electrochemically active bacteria (EAB) and environmental adaptive bacteria Advenella, which may reduce antibiotic resistance genes (ARGs) accumulation. This study suggested that the external circuit control can be effective means to regulate electrochemical characteristics and pollutants removal performance of MFC.202439153696
7887180.9602Double-edged sword effects of sulfate reduction process in sulfur autotrophic denitrification system: Accelerating nitrogen removal and promoting antibiotic resistance genes spread. This study proposed the double-edged sword effects of sulfate reduction process on nitrogen removal and antibiotic resistance genes (ARGs) transmission in sulfur autotrophic denitrification system. Excitation-emission matrix-parallel factor analysis identified the protein-like fraction in soluble microbial products as main endogenous organic matter driving the sulfate reduction process. The resultant sulfide tended to serve as bacterial modulators, augmenting electron transfer processes and mitigating oxidative stress, thereby enhancing sulfur oxidizing bacteria (SOB) activity, rather than extra electron donors. The cooperation between SOB and heterotroph (sulfate reducing bacteria (SRB) and heterotrophic denitrification bacteria (HDB)) were responsible for advanced nitrogen removal, facilitated by multiple metabolic pathways including denitrification, sulfur oxidation, and sulfate reduction. However, SRB and HDB were potential ARGs hosts and assimilatory sulfate reduction pathway positively contributed to ARGs spread. Overall, the sulfate reduction process in sulfur autotrophic denitrification system boosted nitrogen removal process, but also increased the risk of ARGs transmission.202439122125
7985190.9602Differential response of nonadapted ammonia-oxidising archaea and bacteria to drying-rewetting stress. Climate change is expected to increase the frequency of severe drought events followed by heavy rainfall, which will influence growth and activity of soil microorganisms, through osmotic stress and changes in nutrient concentration. There is evidence of rapid recovery of processes and adaptation of communities in soils regularly experiencing drying/rewetting and lower resistance and resilience in nonadapted soils. A microcosm-based study of ammonia-oxidising archaea (AOA) and bacteria (AOB), employing a grassland soil that rarely experiences drought, was used to test this hypothesis and also whether AOB were more resistant and resilient, through greater tolerance of high ammonia concentrations produced during drought and rewetting. Treated soils were dried, incubated for 3 weeks, rewetted, incubated for a further 3 weeks and compared to untreated soils, maintained at a constant moisture content. Nitrate accumulation and AOA and AOB abundance (abundance of respective amoA genes) and community composition (DGGE analysis of AOA amoA and AOB 16S rRNA genes) were poorly adapted to drying-rewetting. AOA abundance and community composition were less resistant than AOB during drought and less resilient after rewetting, at times when ammonium concentration was higher. Data provide evidence for poor adaptation of microbial communities and processes to drying-rewetting in soils with no history of drought and indicate niche differentiation of AOA and AOB associated with high ammonia concentration.201425070168