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873400.7796Effects of Scutellaria baicalensis, Folium Artemisiae argyi, and Galla Chinensis on the protein expression and resistance genes of Exiguobacterium sp. in response to gentamicin. Currently, the issue of antibiotic resistance genes as emerging pollutants in the environment has attracted significant attention in the field of environmental pollution research. Moreover, plant-derived compounds has become a research hotspot due to its high efficiency and low toxicity in reversing microbial intracellular antibiotic resistance genes. However, there is little research on the impact of specific plant extracts on proteins and antibiotic resistance genes during the process of reversing antibiotic resistance genes. In this study, the phosphorus removal performance test, combined with protein Raman spectroscopy analysis and antibiotic resistance gene abundance detection methods, was employed to investigate the effects of Scutellaria baicalensis, Folium Artemisiae argyi, and Galla Chinensis on the phosphorus removal rate, intracellular protein binding sites, and antibiotic resistance gene abundance of Exiguobacterium sp. after exposure to gentamicin. The Raman spectroscopy test results revealed a shift in the protein peaks of Exiguobacterium sp., transitioning from the stable C = C = C = C, C = C, C = C = C structures found in drug-resistant Exiguobacterium sp. to unsaturated bonds of C, CH(2), olefinic unsaturation, and H bonds, similar to those of normal Exiguobacterium sp. Furthermore, the antibiotic resistance gene abundance test results indicated a significant reduction in the abundance of gentamicin resistance genes within the intracellular environment of Exiguobacterium sp. following treatment with these plant extracts. The potential roles of flavonoids in Scutellaria baicalensis and Folium Artemisiae argyi, and tannins in Galla Chinensis in reversing resistance were discussed.202540721471
80710.7507Transcriptomic analysis of Saccharomyces cerevisiae upon honokiol treatment. Honokiol (HNK), one of the main medicinal components in Magnolia officinalis, possesses antimicrobial activity against a variety of pathogenic bacteria and fungi. However, little is known of the molecular mechanisms underpinning the antimicrobial activity. To explore the molecular mechanism of its antifungal activity, we determined the effects of HNK on the mRNA expression profile of Saccharomyces cerevisiae using a DNA microarray approach. HNK markedly induced the expression of genes related to iron uptake and homeostasis. Conversely, genes associated with respiratory electron transport were downregulated, mirroring the effects of iron starvation. Meanwhile, HNK-induced growth deficiency was partly rescued by iron supplementation and HNK reacted with iron, producing iron complexes that depleted iron. These results suggest that HNK treatment induced iron starvation. Additionally, HNK treatment resulted in the upregulation of genes involved in protein synthesis and drug resistance networks. Furthermore, the deletion of PDR5, a gene encoding the plasma membrane ATP binding cassette (ABC) transporter, conferred sensitivity to HNK. Overexpression of PDR5 enhanced resistance of WT and pdr5Δ strains to HNK. Taken together, these findings suggest that HNK, which can be excluded by overexpression of Pdr5, functions in multiple cellular processes in S. cerevisiae, particularly in inducing iron starvation to inhibit cell growth.201728499955
847120.7504Effects of Klebsiella michiganensis LDS17 on Codonopsis pilosula growth, rhizosphere soil enzyme activities, and microflora, and genome-wide analysis of plant growth-promoting genes. Codonopsis pilosula is a perennial herbaceous liana with medicinal value. It is critical to promote Codonopsis pilosula growth through effective and sustainable methods, and the use of plant growth-promoting bacteria (PGPB) is a promising candidate. In this study, we isolated a PGPB, Klebsiella michiganensis LDS17, that produced a highly active 1-aminocyclopropane-1-carboxylate deaminase from the Codonopsis pilosula rhizosphere. The strain exhibited multiple plant growth-promoting properties. The antagonistic activity of strain LDS17 against eight phytopathogenic fungi was investigated, and the results showed that strain LDS17 had obvious antagonistic effects on Rhizoctonia solani, Colletotrichum camelliae, Cytospora chrysosperma, and Phomopsis macrospore with growth inhibition rates of 54.22%, 49.41%, 48.89%, and 41.11%, respectively. Inoculation of strain LDS17 not only significantly increased the growth of Codonopsis pilosula seedlings but also increased the invertase and urease activities, the number of culturable bacteria, actinomycetes, and fungi, as well as the functional diversity of microbial communities in the rhizosphere soil of the seedlings. Heavy metal (HM) resistance tests showed that LDS17 is resistant to copper, zinc, and nickel. Whole-genome analysis of strain LDS17 revealed the genes involved in IAA production, siderophore synthesis, nitrogen fixation, P solubilization, and HM resistance. We further identified a gene (koyR) encoding a plant-responsive LuxR solo in the LDS17 genome. Klebsiella michiganensis LDS17 may therefore be useful in microbial fertilizers for Codonopsis pilosula. The identification of genes related to plant growth and HM resistance provides an important foundation for future analyses of the molecular mechanisms underlying the plant growth promotion and HM resistance of LDS17. IMPORTANCE: We comprehensively evaluated the plant growth-promoting characteristics and heavy metal (HM) resistance ability of the LDS17 strain, as well as the effects of strain LDS17 inoculation on the Codonopsis pilosula seedling growth and the soil qualities in the Codonopsis pilosula rhizosphere. We conducted whole-genome analysis and identified lots of genes and gene clusters contributing to plant-beneficial functions and HM resistance, which is critical for further elucidating the plant growth-promoting mechanism of strain LDS17 and expanding its application in the development of plant growth-promoting agents used in the environment under HM stress.202438563743
847530.7488Antibacterial Activity of Endophytic Bacteria Against Sugar Beet Root Rot Agent by Volatile Organic Compound Production and Induction of Systemic Resistance. The volatile organic compounds (VOCs) produced by endophytic bacteria have a significant role in the control of phytopathogens. In this research, the VOCs produced by the endophytic bacteria Streptomyces sp. B86, Pantoea sp. Dez632, Pseudomonas sp. Bt851, and Stenotrophomonas sp. Sh622 isolated from healthy sugar beet (Beta vulgaris) and sea beet (Beta maritima) were evaluated for their effects on the virulence traits of Bacillus pumilus Isf19, the causal agent of harvested sugar beet root rot disease. The gas chromatographymass spectrometry (GC-MS) analysis revealed that B86, Dez632, Bt851, and Sh622 produced 15, 28, 30, and 20 VOCs, respectively, with high quality. All antagonistic endophytic bacteria produced VOCs that significantly reduced soft root symptoms and inhibited the growth of B. pumilus Isf19 at different levels. The VOCs produced by endophytic bacteria significantly reduced swarming, swimming, and twitching motility by B. pumilus Isf19, which are important to pathogenicity. Our results revealed that VOCs produced by Sh622 and Bt851 significantly reduced attachment of B. pumilus Isf19 cells to sugar beetroots, and also all endophytic bacteria tested significantly reduced chemotaxis motility of the pathogen toward root extract. The VOCs produced by Dez632 and Bt851 significantly upregulated the expression levels of defense genes related to soft rot resistance. Induction of PR1 and NBS-LRR2 genes in sugar beetroot slices suggests the involvement of SA and JA pathways, respectively, in the induction of resistance against pathogen attack. Based on our results, the antibacterial VOCs produced by endophytic bacteria investigated in this study can reduce soft rot incidence.202235722285
872540.7471CuO nanoparticles facilitate soybean suppression of Fusarium root rot by regulating antioxidant enzymes, isoflavone genes, and rhizosphere microbiome. BACKGROUND: Fusarium root rot is a widespread soil-borne disease severely impacting soybean yield and quality. Compared to traditional fertilizers' biological and environmental toxicity, CuO nanoparticles (NPs) hold promise for disease control in a low dose and high efficiency manner. METHODS: We conducted both greenhouse and field experiments, employing enzymatic assays, elemental analysis, qRT-PCR, and microbial sequencing (16S rRNA, ITS) to explore the potential of CuO NPs for sustainable controlling Fusarium-induced soybean disease. RESULTS: Greenhouse experiments showed that foliar spraying of CuO NPs (10, 100, and 500 mg L(-1)) promoted soybean growth more effectively than EDTA-CuNa(2) at the same dose, though 500 CuO NPs caused mild phytotoxicity. CuO NPs effectively controlled root rot, while EDTA-CuNa(2) worsened the disease severity by 0.85-34.04 %. CuO NPs exhibited more substantial antimicrobial effects, inhibiting F. oxysporum mycelial growth and spore germination by 5.04-17.55 % and 10.24-14.41 %, respectively. 100 mg L(-1) CuO NPs was the optimal concentration for balancing soybean growth and disease resistance. Additionally, CuO NPs boosted antioxidant enzyme activity (CAT, POD, and SOD) in leaves and roots, aiding in ROS clearance during pathogen invasion. Compared to the pathogen control, 100 mg L(-1) CuO NPs upregulated the relative expression of seven isoflavone-related genes (Gm4CL, GmCHS8, GmCHR, GmCHI1a, GmIFS1, GmUGT1, and GmMYB176) by 1.18-4.51 fold, thereby enhancing soybean disease resistance in place of progesterone-receptor (PR) genes. Field trials revealed that CuO NPs' high leaf-to-root translocation modulated soybean rhizosphere microecology. Compared to the pathogen control, 100 mg L(-1) CuO NPs increased nitrogen-fixing bacteria (Rhizobium, Azospirillum, Azotobacter) and restored disease-resistant bacteria (Pseudomonas, Burkholderia) and fungi (Trichoderma, Penicillium) to healthy levels. Furthermore, 100 mg L(-1) CuO NPs increased beneficial bacteria (Pedosphaeraceae, Xanthobacteraceae, SCI84, etc.) and fungi (Trichoderma, Curvularia, Hypocreales, etc.), which negatively correlated with F. oxysporum, while recruiting functional microbes to enhance soybean yield. CONCLUSION: 100 mg L(-1) CuO NPs effectively promoting soybean growth and providing strong resistance against root rot disease by improving antioxidant enzyme activity, regulating the relative expression of isoflavone-related genes, increasing beneficial bacteria and fungi and restoring disease-resistant. Our findings suggest that CuO NPs offer an environmentally sustainable strategy for managing soybean disease, with great potential for green production.202540096759
880650.7463Cyclopropanation and membrane unsaturation improve antibiotic resistance of swarmer Pseudomonas and its sod mutants exposed to radiations, in vitro and in silico approch. It was known that UVc irradiation increases the reactive oxygen species' (ROS) levels in bacteria hence the intervention of antioxidant enzymes and causes also changes in fatty acids (FAs) composition enabling bacteria to face antibiotics. Here, we intended to elucidate an interrelationship between SOD and susceptibility to antibiotics by studying FA membrane composition of UVc-treated P. aeruginosa PAO1 and its isogenic mutants (sodM, sodB and sod MB) membrane, after treatment with antibiotics. Swarmer mutants defective in genes encoding superoxide dismutase were pre-exposed to UVc radiations and then tested by disk diffusion method for their contribution to antibiotic tolerance in comparison with the P. aeruginosa wild type (WT). Moreover, fatty acid composition of untreated and UVc-treated WT and sod mutants was examined by Gaz chromatography and correlated to antibiotic resistance. Firstly, it has been demonstrated that after UVc exposure, swarmer WT strain, sodM and sodB mutants remain resistant to polymixin B, a membrane target antibiotic, through membrane unsaturation supported by the intervention of Mn-SOD after short UVc exposure and cyclopropanation of unsaturated FAs supported by the action of Fe-SOD after longer UVc exposure. However, resistance for ciprofloxacin is correlated with increase in saturated FAs. This correlation has been confirmed by a molecular docking approach showing that biotin carboxylase, involved in the initial stage of FA biosynthesis, exhibits a high affinity for ciprofloxacin. This investigation has explored the correlation of antibiotic resistance with FA content of swarmer P.aeruginosa pre-exposed to UVc radiations, confirmed to be antibiotic target dependant.202438869625
789060.7462The control of red water occurrence and opportunistic pathogens risks in drinking water distribution systems: A review. Many problems in drinking water distribution systems (DWDSs) are caused by microbe, such as biofilm formation, biocorrosion and opportunistic pathogens growth. More iron release from corrosion scales may induce red water. Biofilm played great roles on the corrosion. The iron-oxidizing bacteria (IOB) promoted corrosion. However, when iron-reducing bacteria (IRB) and nitrate-reducing bacteria (NRB) became the main bacteria in biofilm, they could induce iron redox cycling in corrosion process. This process enhanced the precipitation of iron oxides and formation of more Fe(3)O(4) in corrosion scales, which inhibited corrosion effectively. Therefore, the IRB and NRB in the biofilm can reduce iron release and red water occurrence. Moreover, there are many opportunistic pathogens in biofilm of DWDSs. The opportunistic pathogens growth in DWDSs related to the bacterial community changes due to the effects of micropollutants. Micropollutants increased the number of bacteria with antibiotic resistance genes (ARGs). Furthermore, extracellular polymeric substances (EPS) production was increased by the antibiotic resistant bacteria, leading to greater bacterial aggregation and adsorption, increasing the chlorine-resistance capability, which was responsible for the enhancement of the particle-associated opportunistic pathogens in DWDSs. Moreover, O(3)-biological activated carbon filtration-UV-Cl(2) treatment could be used to control the iron release, red water occurrence and opportunistic pathogens growth in DWDSs.202134593198
791470.7460Response of partial nitrification sludge to the single and combined stress of CuO nanoparticles and sulfamethoxazole antibiotic on microbial activity, community and resistance genes. Considering the inevitable release of antibiotics and nanoparticles (NPs) into the nitrogen containing wastewater, the combined impact of CuO NPs and sulfamethoxazole (SMX) antibiotic on partial nitrification (PN) process was investigated in four identical reactors. Results showed that the bioactivity of the aerobic ammonia-oxidizing bacteria (AOB) decreased by half after they were exposed to the combination of CuO NPs and SMX for short-term; however, there was no obvious variation in the bioactivity of AOB when they were exposed to either CuO NPs or SMX. During long-term exposure, the ammonia removal efficiency (ARE) of CuO NPs improved whereas that of SMX decreased, while the combination of CuO NPs and SMX significantly decreased ARE from 62.9% (in control) to 38.2% and had an unsatisfactory self-recovery performance. The combination of CuO NPs and SMX significantly changed the composition of microbial community, decreased the abundance of AOB, and significantly suppressed PN process. Reegarding the resistance genes, the CuO NPs-SMX combination did not improve the expression of copA, cusA, sul1 and sul2; however, it significantly induced the expression of sul3 and sulA.202032050397
848780.7455Mechanisms of nano zero-valent iron in enhancing dibenzofuran degradation by a Rhodococcus sp.: Trade-offs between ATP production and protection against reactive oxygen species. Nano zero-valent iron (nZVI) can enhance pollutants biodegradation, but it displays toxicity towards microorganisms. Gram-positive (G(+)) bacteria exhibit greater resistance to nZVI than Gram-negative bacteria. However, mechanisms of nZVI accelerating pollutants degradation by G(+) bacteria remain unclear. Herein, we explored effects of nZVI on a G(+) bacterium, Rhodococcus sp. strain p52, and mechanisms by which nZVI accelerates biodegradation of dibenzofuran, a typical polycyclic aromatic compound. Electron microscopy and energy dispersive spectroscopy analysis revealed that nZVI could penetrate cell membranes, which caused damage and growth inhibition. nZVI promoted dibenzofuran biodegradation at certain concentrations, while higher concentration functioned later due to the delayed reactive oxygen species (ROS) mitigation. Transcriptomic analysis revealed that cells adopted response mechanisms to handle the elevated ROS induced by nZVI. ATP production was enhanced by accelerated dibenzofuran degradation, providing energy for protein synthesis related to antioxidant stress and damage repair. Meanwhile, electron transport chain (ETC) was adjusted to mitigate ROS accumulation, which involved downregulating expression of ETC complex I-related genes, as well as upregulating expression of the genes for the ROS-scavenging cytochrome bd complex and ETC complex II. These findings revealed the mechanisms underlying nZVI-enhanced biodegradation by G(+) bacteria, offering insights into optimizing bioremediation strategies involving nZVI.202539549579
811290.7454Fate of antibiotic resistance bacteria and genes during enhanced anaerobic digestion of sewage sludge by microwave pretreatment. The fate of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) were investigated during the sludge anaerobic digestion (AD) with microwave-acid (MW-H), microwave (MW) and microwave-H2O2-alkaline (MW-H2O2) pretreatments. Results showed that combined MW pretreatment especially for the MW-H pretreatment could efficiently reduce the ARB concentration, and most ARG concentrations tended to attenuate during the pretreatment. The subsequent AD showed evident removal of the ARB, but most ARGs were enriched after AD. Only the concentration of tetX kept continuous declination during the whole sludge treatment. The total ARGs concentration showed significant correlation with 16S rRNA during the pretreatment and AD. Compared with unpretreated sludge, the AD of MW and MW-H2O2 pretreated sludge presented slightly better ARB and ARGs reduction efficiency.201626970692
9029100.7451The Effect of Benzyl Isothiocyanate on the Expression of Genes Encoding NADH Oxidase and Fibronectin-Binding Protein in Oral Streptococcal Biofilms. Recent studies have shown that antimicrobial treatment results in up- or down regulation of several virulence-associated genes in bacterial biofilms. The genes encoding NADH oxidase (nox) and fibronectin-binding protein (fbp) are known to play important roles in biofilm growth of some oral bacterial species. The objective was to study the effect of benzyl isothiocyanate (BITC), an antimicrobial agent from Miswak plant, on the expression of nox and fbp genes in some oral streptococci. The biofilms were treated with BITC and mRNA expression of nox and fbp genes was measured by comparative ΔΔCt method. The highest amount of biofilm mass was produced by A. defectiva, followed by S. gordonii, S. mutans, G. elegans and G. adiacens. Upon treatment with BITC, S. gordonii biofilms showed highest folds change in mRNA expression for both fbp and nox genes followed by S. mutans, A. defectiva, and G. adiacens. G. elegans mRNA levels for nox were extremely low. In conclusion, BITC treatment of the biofilms caused an upregulation of biofilm-associated genes fbp and nox genes in most of the tested species suggesting the significance of these genes in biofilm lifestyle of these oral bacteria and needs further investigation to understand if it contributes to antimicrobial resistance.202235478497
7935110.7451Removal 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
806120.7449A two-component small multidrug resistance pump functions as a metabolic valve during nicotine catabolism by Arthrobacter nicotinovorans. The genes nepAB of a small multidrug resistance (SMR) pump were identified as part of the pAO1-encoded nicotine regulon responsible for nicotine catabolism in Arthrobacter nicotinovorans. When [(14)C]nicotine was added to the growth medium the bacteria exported the (14)C-labelled end product of nicotine catabolism, methylamine. In the presence of the proton-motive force inhibitors 2,4-dinitrophenol (DNP), carbonyl cyanide m-chlorophenylhydrazone (CCCP) or the proton ionophore nigericin, export of methylamine was inhibited and radioactivity accumulated inside the bacteria. Efflux of [(14)C]nicotine-derived radioactivity from bacteria was also inhibited in a pmfR : cmx strain with downregulated nepAB expression. Because of low amine oxidase levels in the pmfR : cmx strain, gamma-N-methylaminobutyrate, the methylamine precursor, accumulated. Complementation of this strain with the nepAB genes, carried on a plasmid, restored the efflux of nicotine breakdown products. Both NepA and NepB were required for full export activity, indicating that they form a two-component efflux pump. NepAB may function as a metabolic valve by exporting methylamine, the end product of nicotine catabolism, and, in conditions under which it accumulates, the intermediate gamma-N-methylaminobutyrate.200717464069
6787130.7448Impact 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
7898140.7448Effects of graphite and Mn ore media on electro-active bacteria enrichment and fate of antibiotic and corresponding resistance gene in up flow microbial fuel cell constructed wetland. This study assessed the influence of substrate type on pollutants removal, antibiotic resistance gene (ARG) fate and bacterial community evolution in up-flow microbial fuel cell constructed wetlands (UCW-MFC) with graphite and Mn ore electrode substrates. Better COD removal and higher bacterial community diversity and electricity generation performance were achieved in Mn ore constructed UCW-MFC (Mn). However, the lower concentration of sulfadiazine (SDZ) and the total abundances of ARGs were obtained in the effluent in the graphite constructed UCW-MFC (s), which may be related to higher graphite adsorption and filter capacity. Notably, both reactors can remove more than 97.8% of ciprofloxacin. In addition, significant negative correlations were observed between SDZ, COD concentration, ARG abundances and bacterial a-diversity indices. The LEfse analysis revealed significantly different bacterial communities due to the substrate differences in the two reactors, and Geobacter, a typical model electro-active bacteria (EAB), was greatly enriched on the anode of UCW-MFC (Mn). In contrast, the relative abundance of methanogens (Methanosaeta) was inhibited. PICRUSt analysis results further demonstrated that the abundance of extracellular electron transfer related functional genes was increased, but the methanogen function genes and multiple antibiotic resistance genes in UCW-MFC (Mn) anode were reduced. Redundancy analyses indicated that substrate type, antibiotic accumulation and bacterial community were the main factors affecting ARGs. Moreover, the potential ARG hosts and the co-occurrence of ARGs and intI1 were revealed by network analysis.201931442759
8765150.7447Pseudomonas chlororaphis IRHB3 assemblies beneficial microbes and activates JA-mediated resistance to promote nutrient utilization and inhibit pathogen attack. INTRODUCTION: The rhizosphere microbiome is critical to plant health and resistance. PGPR are well known as plant-beneficial bacteria and generally regulate nutrient utilization as well as plant responses to environmental stimuli. In our previous work, one typical PGPR strain, Pseudomonas chlororaphis IRHB3, isolated from the soybean rhizosphere, had positive impacts on soil-borne disease suppression and growth promotion in the greenhouse, but its biocontrol mechanism and application in the field are not unclear. METHODS: In the current study, IRHB3 was introduced into field soil, and its effects on the local rhizosphere microbiome, disease resistance, and soybean growth were comprehensively analyzed through high-throughput sequencing and physiological and molecular methods. RESULTS AND DISCUSSION: We found that IRHB3 significantly increased the richness of the bacterial community but not the structure of the soybean rhizosphere. Functional bacteria related to phosphorus solubilization and nitrogen fixation, such as Geobacter, Geomonas, Candidatus Solibacter, Occallatibacter, and Candidatus Koribacter, were recruited in rich abundance by IRHB3 to the soybean rhizosphere as compared to those without IRHB3. In addition, the IRHB3 supplement obviously maintained the homeostasis of the rhizosphere microbiome that was disturbed by F. oxysporum, resulting in a lower disease index of root rot when compared with F. oxysporum. Furthermore, JA-mediated induced resistance was rapidly activated by IRHB3 following PDF1.2 and LOX2 expression, and meanwhile, a set of nodulation genes, GmENOD40b, GmNIN-2b, and GmRIC1, were also considerably induced by IRHB3 to improve nitrogen fixation ability and promote soybean yield, even when plants were infected by F. oxysporum. Thus, IRHB3 tends to synergistically interact with local rhizosphere microbes to promote host growth and induce host resistance in the field.202438380096
539160.7445A role of ygfZ in the Escherichia coli response to plumbagin challenge. Plumbagin is found in many herbal plants and inhibits the growth of various bacteria. Escherichia coli strains are relatively resistant to this drug. The mechanism of resistance is not clear. Previous findings showed that plumbagin treatment triggered up-regulation of many genes in E. coli including ahpC, mdaB, nfnB, nfo, sodA, yggX and ygfZ. By analyzing minimal inhibition concentration and inhibition zones of plumbagin in various gene-disruption mutants, ygfZ and sodA were found critical for the bacteria to resist plumbagin toxicity. We also found that the roles of YgfZ and SodA in detoxifying plumbagin are independent of each other. This is because of the fact that ectopically expressed SodA reduced the superoxide stress but not restore the resistance of bacteria when encountering plumbagin at the absence of ygfZ. On the other hand, an ectopically expressed YgfZ was unable to complement and failed to rescue the plumbagin resistance when sodA was perturbed. Furthermore, mutagenesis analysis showed that residue Cys228 within YgfZ fingerprint region was critical for the resistance of E. coli to plumbagin. By solvent extraction and HPLC analysis to follow the fate of the chemical, it was found that plumbagin vanished apparently from the culture of YgfZ-expressing E. coli. A less toxic form, methylated plumbagin, which may represent one of the YgfZ-dependent metabolites, was found in the culture supernatant of the wild type E. coli but not in the ΔygfZ mutant. Our results showed that the presence of ygfZ is not only critical for the E coli resistance to plumbagin but also facilitates the plumbagin degradation.201021059273
7897170.7445Enhanced removal of antibiotic and antibiotic resistance genes by coupling biofilm electrode reactor and manganese ore substrate up-flow microbial fuel cell constructed wetland system. Manganese ore substrate up-flow microbial fuel cell constructed wetland (UCW-MFC(Mn)) as an innovative wastewater treatment technology for purifying antibiotics and electricity generation with few antibiotic resistance genes (ARGs) generation has attracted attention. However, antibiotic purifying effects should be further enhanced. In this study, a biofilm electrode reactor (BER) that needs direct current driving was powered by a Mn ore anode (UCW-MFC(Mn)) to form a coupled system without requiring direct-current source. Removal efficiencies of sulfadiazine (SDZ), ciprofloxacin (CIP) and the corresponding ARGs in the coupled system were compared with composite (BER was powered by direct-current source) and anaerobic systems (both of BER and UCW-MFC were in open circuit mode). The result showed that higher antibiotic removal efficiency (94% for SDZ and 99.1% for CIP) in the coupled system was achieved than the anaerobic system (88.5% for SDZ and 98.2% for CIP). Moreover, electrical stimulation reduced antibiotic selective pressure and horizontal gene transfer potential in BER, and UCW-MFC further reduced ARG abundances by strengthening the electro-adsorption of ARG hosts determined by Network analysis. Bacterial community diversity continuously decreased in BER while it increased in UCW-MFC, indicating that BER mitigated the toxicity of antibiotic. Degree of modularity, some functional bacteria (antibiotic degrading bacteria, fermentative bacteria and EAB), and P450 enzyme related to antibiotic and xenobiotics biodegradation genes were enriched in electric field existing UCW-MFC, accounting for the higher degradation efficiency. In conclusion, this study provided an effective strategy for removing antibiotics and ARGs in wastewater by operating a BER-UCW-MFC coupled system.202337437616
8488180.7444Antihistamine drug loratadine at environmentally relevant concentrations promotes conjugative transfer of antibiotic resistance genes: Coeffect of oxidative stress and ion transport. Due to the widespread use of loratadine (LOR) as an antihistamine, it is widely distributed in the environment as an emerging contaminant. However, its impact on the dissemination of antibiotic resistance genes (ARGs) remains unclear. This study investigated the effect of LOR on the conjugative transfer of ARGs and elucidated the potential mechanisms through transcriptome analysis. The results showed that LOR significantly promoted the frequency of conjugative transfer up to 1.5- to 8.6-fold higher compared with the control group. Exposure to LOR increased reactive oxidative species (ROS) and intracellular Ca(2+) concentrations, leading to the upregulation of expression of genes related to transmembrane transport and SOS response. Meanwhile, it stimulated the increase of cell membrane permeability. Moreover, LOR exposure could enhance H(+) efflux in donor bacteria, resulting in the decrease of intracellular pH and the elevation of transmembrane potential, which could induce the increase of ion transport, thereby promoting plasmid efflux from the cell membrane. Based on this, we inferred that LOR can induce an increase in ROS level and intracellular Ca(2+) concentrations, and promoted the efflux of intracellular H(+). This, in turn, triggered the intensification of various ion transport processes on the cell membrane, thereby increasing membrane permeability and accelerating plasmid efflux. Ultimately, the coeffect of oxidative stress response and ion transport promoted conjugative transfer. This study demonstrated that LOR significantly promotes plasmid-mediated conjugative transfer of ARGs, providing novel insights into the mechanisms underlying this process.202539919578
7874190.7443Phenacetin promoted the rapid start-up and stable maintenance of partial nitrification: Responses of nitrifiers and antibiotic resistance genes. Phenacetin (PNCT) belongs to one of the earliest synthetic antipyretics. However, impact of PNCT on nitrifying microorganisms in wastewater treatment plants and its potential microbial mechanism was still unclear. In this study, PN could be initiated within six days by PNCT anaerobic soaking treatment (8 mg/L). In order to improve the stable performance of PN, 21 times of PNCT aerobic soaking treatment every three days was conducted and PN was stabilized for 191 days. After PN was damaged, ten times of PNCT aerobic soaking treatment every three days was conducted and PN was recovered after once soaking, maintained over 88 days. Ammonia oxidizing bacteria might change the dominant oligotype to gradually adjust to PNCT, and the increase of abundance and activity of Nitrosomonas promoted the initiation of PN. For nitrite-oxidizing bacteria (NOB), the increase of Candidatus Nitrotoga and Nitrospira destroyed PN, but PN could be recovered after once aerobic soaking illustrating NOB was not resistant to PNCT. KEGG and COG analysis suggested PNCT might disrupt rTCA cycle of Nitrospira, resulting in the decrease of relative abundance of Nitrospira. Moreover, PNCT did not lead to the sharp increase of absolute abundances of antibiotic resistance genes (ARGs), and the risk of ARGs transmission was negligible.202438744392