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848700.9938Mechanisms 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
853210.9936Simultaneous volatile fatty acids promotion and antibiotic resistance genes reduction in fluoranthene-induced sludge alkaline fermentation: Regulation of microbial consortia and cell functions. The impact and mechanism of fluoranthene (Flr), a typical polycyclic aromatic hydrocarbon highly detected in sludge, on alkaline fermentation for volatile fatty acids (VFAs) recovery and antibiotic resistance genes (ARGs) transfer were studied. The results demonstrated that VFAs production increased from 2189 to 4272 mg COD/L with a simultaneous reduction of ARGs with Flr. The hydrolytic enzymes and genes related to glucose and amino acid metabolism were provoked. Also, Flr benefited for the enrichment of hydrolytic-acidifying consortia (i.e., Parabacteroides and Alkalibaculum) while reduced VFAs consumers (i.e., Rubrivivax) and ARGs potential hosts (i.e., Rubrivivax and Pseudomonas). Metagenomic analysis indicated that the genes related to cell wall synthesis, biofilm formation and substrate transporters to maintain high VFAs-producer activities were upregulated. Moreover, cell functions of efflux pump and Type IV secretion system were suppressed to inhibit ARGs proliferation. This study provided intrinsic mechanisms of Flr-induced VFAs promotion and ARGs reduction during alkaline fermentation.202438266788
52320.9934Sulfide-carbonate-mineralized functional bacterial consortium for cadmium removal in flue gas. Sulfide-carbonate-mineralized functional bacterial consortium was constructed for flue gas cadmium biomineralization. A membrane biofilm reactor (MBfR) using the bacterial consortium containing sulfate reducing bacteria (SRB) and denitrifying bacteria (DNB) was investigated for flue gas cadmium (Cd) removal. Cadmium removal efficiency achieved 90%. The bacterial consortium containing Citrobacter, Desulfocurvus and Stappia were dominated for cadmium resistance-nitrate-sulfate reduction. Under flue gas cadmium stress, ten cadmium resistance genes (czcA, czcB, czcC, czcD, cadA, cadB, cadC, cueR, copZ, zntA), and seven genes related to sulfate reduction, increased in abundance; whereas others, nine genes related to denitrification, decreased, indicating that cadmium stress was advantageous to sulfate reduction in the competition with denitrification. A bacterial consortium could capable of simultaneously cadmium resistance, sulfate reduction and denitrification. Microbial induced carbonate precipitation (MICP) and biological adsorption process would gradually yield to sulfide-mineralized process. Flue gas cadmium could transform to Cd-EPS, cadmium carbonate (CdCO(3)) and cadmium sulfide (CdS) bioprecipitate. The functional bacterial consortium was an efficient and eco-friendly bifunctional bacterial consortium for sulfide-carbonate-mineralized of cadmium. This provides a green and low-carbon advanced treatment technology using sulfide-carbonate-mineralized functional bacterial consortium for the removal of cadmium or other hazardous heavy metal contaminants in flue gas.202439019186
788030.9931The synergistic mechanism of β-lactam antibiotic removal between ammonia-oxidizing microorganisms and heterotrophs. Nitrifying system is an effective strategy to remove numerous antibiotics, however, the contribution of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA) and heterotrophs for antibiotic removal are still unclear. In this study, the mechanism of β-lactam antibiotic (cefalexin, CFX) removal was studied in a nitrifying sludge system. Results showed that CFX was synergistically removed by AOB (Nitrosomonas, played a major role) and AOA (Candidatus_Nitrososphaera) through ammonia monooxygenase-mediated co-metabolism, and by heterotrophs (Pseudofulvimonas, Hydrogenophaga, RB41, Thauera, UTCFX1, Plasticicumulans, Phaeodactylibacter) through antibiotic resistance genes (ARGs)-encoded β-lactamases-mediated hydrolysis. Regardless of increased archaeal and heterotrophic CFX removal with the upregulation of amoA in AOA and ARGs, the system exhibited poorer CFX removal performance at 10 mg/L, mainly due to the inhibition of AOB. This study provides new reference for the important roles of heterotrophs and ARGs, opening the possibilities for the application of ARGs in antibiotic biodegradation.202336174754
848640.9929Multidrug-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
787950.9928Multidrug-resistant plasmid RP4 increases NO and N(2)O yields via the electron transport system in Nitrosomonas europaea ammonia oxidation. Antibiotic resistance genes (ARGs) have recently become an important public health problem and therefore several studies have characterized ARG composition and distribution. However, few studies have assessed their impact on important functional microorganisms in the environment. Therefore, our study sought to investigate the mechanisms through which multidrug-resistant plasmid RP4 affected the ammonia oxidation capacity of ammonia-oxidizing bacteria, which play a key role in the nitrogen cycle. The ammonia oxidation capacity of N. europaea ATCC25978 (RP4) was significantly inhibited, and NO and N(2)O were produced instead of nitrite. Our findings demonstrated that the decrease in electrons from NH(2)OH decreased the ammonia monooxygenase (AMO) activity, leading to a decrease in ammonia consumption. In the ammonia oxidation process, N. europaea ATCC25978 (RP4) exhibited ATP and NADH accumulation. The corresponding mechanism was the overactivation of Complex Ⅰ, ATPase, and the TCA cycle by the RP4 plasmid. The genes encoding TCA cycle enzymes related to energy generation, including gltA, icd, sucD, and NE0773, were upregulated in N. europaea ATCC25978 (RP4). These results demonstrate the ecological risks of ARGs, including the inhibition of the ammonia oxidation process and an increased production of greenhouse gases such as NO and N(2)O.202337421866
853160.9928Biotransformation mechanism of Vibrio diabolicus to sulfamethoxazole at transcriptional level. Sulfamethoxazole (SMX) has attracted much attention due to its high probability of detection in the environment. Marine bacteria Vibrio diabolicus strain L2-2 has been proven to be able to transform SMX. In this study, the potential resistance and biotransformation mechanism of strain L2-2 to SMX, and key genes responses to SMX at environmental concentrations were researched. KEGG pathways were enriched by down-regulated genes including degradation of L-Leucine, L-Isoleucine, and fatty acid metabolism. Resistance mechanism could be concluded as the enhancement of membrane transport, antioxidation, response regulator, repair proteins, and ribosome protection. Biotransformation genes might involve in arylamine N-acetyltransferases (nat), cytochrome c553 (cyc-553) and acyl-CoA synthetase (acs). At the environmental concentration of SMX (0.1-10 μg/L), nat was not be activated, which meant the acetylation of SMX might not occur in the environment; however, cyc-553 was up-regulated under SMX stress of 1 μg/L, which indicated the hydroxylation of SMX could occur in the environment. Besides, the membrane transport and antioxidation of strain L2-2 could be activated under SMX stress of 10 μg/L. The results provided a better understanding of resistance and biotransformation of bacteria to SMX and would support related researches about the impacts of environmental antibiotics.202133429311
789370.9926Removal 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
788780.9925Double-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
788490.9925Underlying the inhibition mechanisms of sulfate and lincomycin on long-term anaerobic digestion: Microbial response and antibiotic resistance genes distribution. This study evaluated the resilience of a long-term anaerobic treatment system exposed to sulfate, lincomycin (LCM) and their combined stress. LCM was found to impede anaerobic propionate degradation, while sulfate for restraining methanogenic acetate utilization. The combined stress, with influent LCM of 200 mg/L and sulfate of 1404 mg/L, revealed severer inhibition on anaerobic digestion than individual inhibition, leading to 73.9 % and 38.5 % decrease in methane production and sulfate removal, respectively. Suppression on propionate-oxidizing bacteria like unclassified_f__Anaerolineae and unclassified_f__Syntrophaceae further demonstrated LCM's inhibitory effect on propionate degradation. Besides, the down-regulation of genes encoding dissimilatory sulfate reduction enzymes caused by LCM triggered great inhibition on sulfate reduction. A notable increase in ARGs was detected under sulfate-stressed condition, owing to its obvious enrichment of tetracycline-resistant genes. Genera including unclassified_f__Syntrophaceae, unclassified_f__Geobacteraceae and unclassified_f__Anaerolineaceae were identified as dominant host of ARGs and enriched by sulfate addition. Overall, these results could provide the theoretical basis for further enhancement on anaerobic digestion of pharmaceutical wastewater containing sulfate and lincomycin.202438185146
8543100.9925Soil bacteria, genes, and metabolites stimulated during sulfur cycling and cadmium mobilization under sodium sulfate stress. Sodium sulfate stress is known to improve cadmium (Cd) mobilization in soil and microbial sulfur oxidation, Cd resistance, and the accumulation of stress tolerance-associated metabolites has been correlated with increased soil Cd availability and toxicity. In this study, aerobic soil microcosms with Cd-contamination were stimulated with sodium sulfate to investigate its effects on soil microbial community structure, functional genes, and associated metabolite profiles. Metagenomic analysis revealed that sulfur oxidizing and Cd-resistant bacteria carried gene clusters encoding sox, dsr, and sqr genes, and znt, czc, and cad genes, respectively. Exposure to sodium sulfate resulted in the reprogram of soil metabolites. In particular, intensification of sulfur metabolism triggered an up-regulation in the tricarboxylic acid (TCA) cycle, which promoted the secretion of carboxylic acids and their precursors by soil bacteria. The accumulation of organic acids induced in response to high sodium sulfate dosages potentially drove an observed increase in Cd mobility. Pseudomonas and Erythrobacter spp. exhibited a high capacity for adaptation to heavy metal- or sulfur-induced stress, evident by an increased abundance of genes and metabolites for sulfur cycling and Cd resistance. These results provide valuable insights towards understanding the microbial mechanisms of sulfur transformation and Cd dissolution under saline stress.202134214562
8540110.9925Metagenomic insights into the mechanism for the rapid enrichment and high stability of Candidatus Brocadia facilitated by Fe(Ⅲ). The rapid enrichment of anammox bacteria and its fragile resistance to adverse environment are the critical problems facing of anammox processes. As an abundant component in anammox bacteria, iron has been proved to promote the activity and growth of anammox bacteria in the mature anammox systems, but the functional and metabolic profiles in Fe(III) enhanced emerging anammox systems have not been evaluated. Results indicated that the relative abundance of functional genes involved in oxidative phosphorylation, nitrogen metabolism, cofactors synthesis, and extracellular polymers synthesis pathways was significantly promoted in the system added with 5 mg/L Fe(III) (R5). These enhanced pathways were crucial to energy generation, nitrogen removal, cell activity and proliferation, and microbial self-defense, thereby accelerating the enrichment of anammox bacteria Ca. Brocadia and facilitating their resistance to adverse environments. Microbial community analysis showed that the proportion of Ca. Brocadia in R5 also increased to 64.42 %. Hence, R5 could adapt rapidly to the increased nitrogen loading rate and increase the nitrogen removal rate by 108 % compared to the system without Fe(III) addition. However, the addition of 10 and 20 mg/L Fe(III) showed inhibitory effects on the growth and activity of anammox bacteria, which exhibited the lower relative abundance of Ca. Brocadia and unstable or even collapsed nitrogen removal performance. This study not only clarified the concentration range of Fe(III) that promoted and inhibited the enrichment of anammox bacteria, but also deepened our understanding of the functional and metabolic mechanisms underlying enhanced enrichment of anammox bacteria by Fe(III), providing a potential strategy to hasten the start-up of anammox from conventional activated sludge.202438309072
8484120.9923Deciphering the acidophilia and acid resistance in Acetilactobacillus jinshanensis dominating baijiu fermentation through multi-omics analysis. Lactic acid bacteria (LAB) are pivotal in constructing the intricate bio-catalytic networks underlying traditional fermented foods such as Baijiu. However, LAB and their metabolic mechanisms are partially understood in Moutai flavor Baijiu fermentation. Here, we found that Acetilactobacillus jinshanensis became the· dominant species with relative abundance reaching 92%, where the acid accumulated rapidly and peaked at almost 30 g/kg in Moutai flavor Baijiu. After separation, purification, and cultivation, A. jinshanensis exhibited pronounced acidophilia and higher acid resistance compared to other LAB. Further integrated multi-omics analysis revealed that fatty acid synthesis, cell membrane integrity, pHi and redox homeostasis maintenance, protein and amide syntheses were possibly crucial acid-resistant mechanisms in A. jinshanensis. Structural proteomics indicated that the surfaces of A. jinshanensis proteases contained more positively charged amino acid residues to maintain protein stability in acidic environments. The genes HSP20 and acpP were identified as acid-resistant genes for A. jinshanensis by heterologous expression analysis. These findings not only enhance our understanding of LAB in Baijiu, providing a scientific basis for acid regulation for production process, but also offer valuable insights for studying core species in other fermentation systems.202539448165
8816130.9923Sulfate-reducing bacteria block cadmium and lead uptake in rice by regulating sulfur metabolism. AIM: This study was dedicated to investigating the role of sulfur metabolic processes in sulfate-reducing bacteria in plant resistance to heavy metal contamination. METHODS AND RESULTS: We constructed sulfate-reducing bacterial communities based on the functional properties of sulfate-reducing strains and then screened out the most effective sulfate-reducing bacterial community SYN1, that prevented Cd and Pb uptake in rice through a hydroponic experiment. This community lowered Cd levels in the roots and upper roots by 36.60% and 39.88%, respectively, and Pb levels by 35.96% and 51.54%. We also compared two treatment groups, inoculated with SYN1 and exogenously added GSH, and found that both enhanced the antioxidant response of the plants, increased the lignin and GSH contents and the expression of genes related to the phenylpropane biosynthesis pathway (OsCAD, Os4CL, OsCOMT, OsPOD, OsC3H, and OsPAL), and decreased the expression of heavy metal transporter genes (OsHMA2, OsIRT1) expression. There were no significant differences between the two treatments. CONCLUSIONS: Sulfate-reducing bacteria produce GSH through the sulfur assimilation pathway, and GSH can directly chelate heavy metals or enhance plant antioxidant enzyme activities and regulate processes such as the uptake and translocation of heavy metals, thus enhancing plant resistance to heavy metal toxicity.202539870375
8769140.9922Transgenic soybean of GsMYB10 shapes rhizosphere microbes to promote resistance to aluminum (Al) toxicity. Plant resistance genes could affect rhizosphere microbiota, which in turn enhanced plant resistance to stresses. Our previous study found that overexpression of the GsMYB10 gene led to enhanced tolerance of soybean plants to aluminum (Al) toxicity. However, whether GsMYB10 gene could regulate rhizosphere microbiota to mitigate Al toxicity remains unclear. Here, we analyzed the rhizosphere microbiomes of HC6 soybean (WT) and transgenic soybean (trans-GsMYB10) at three Al concentrations, and constructed three different synthetic microbial communities (SynComs), including bacterial, fungal and cross-kingdom (bacteria and fungi) SynComs to verify their role in improving Al tolerance of soybean. Trans-GsMYB10 shaped the rhizosphere microbial communities and harbored some beneficial microbes, such as Bacillus, Aspergillus and Talaromyces under Al toxicity. Fungal and cross-kingdom SynComs showed a more effective role than the bacterial one in resistance to Al stress, and these SynComs helped soybean resist Al toxicity via affecting some functional genes that involved cell wall biosynthesis and organic acid transport etc. Overall, this study reveals the mechanism of soybean functional genes regulating the synergistic resistance of rhizosphere microbiota and plants to Al toxicity, and also highlights the possibility of focusing on the rhizobial microbial community as a potential molecular breeding target to produce crops.202337187122
8544150.9922Closed fixed-bed bacteria-algae biofilm reactor: A promising solution for phenol containing wastewater treatment and resource transformation. This study focuses on treating phenolic wastewater with a novel closed fixed-bed bacteria-algae biofilm reactor (CF-BABR) to enhance resource transformation for phenolic substances. The CF-BABR showed strong impact - load resistance and stable degradation efficiency, fully degrading phenolic compounds at concentrations from 0 to 150 mg/L. From the inflow to the outflow, the effective sequences, abundance, and diversity of bacteria decreased. Chlorobaculum was the dominant bacterium for phenolic pollutant degradation. The abundance of fungi decreased gradually, while their diversity increased. Kalenjinia and Cutaneotrichosporon played a synergistic role in reducing pollutant toxicity. The high - concentration pollutants at the influent led to a higher abundance of microalgal communities, and Scenedesmaceae became the most dominant algal family, which was positively correlated with the degradation of phenolic compounds. Functional gene prediction indicated that the abundance of functional genes in bacteria decreased overall along the wastewater flow. Carbohydrate metabolism and amino acid metabolism were the most active secondary pathways. In fungi, the predicted gene functions had the highest abundance in the upstream region. Metabolic intermediates such as organic acids and derivatives, lipids and lipid - like molecules, and carboxylic acids and derivatives demonstrated the degradation effect of CF-BABR on phenolic compounds.202540194331
520160.9922Respiratory chain components are required for peptidoglycan recognition protein-induced thiol depletion and killing in Bacillus subtilis and Escherichia coli. Mammalian peptidoglycan recognition proteins (PGRPs or PGLYRPs) kill bacteria through induction of synergistic oxidative, thiol, and metal stress. Tn-seq screening of Bacillus subtilis transposon insertion library revealed that mutants in the shikimate pathway of chorismate synthesis had high survival following PGLYRP4 treatment. Deletion mutants for these genes had decreased amounts of menaquinone (MK), increased resistance to killing, and attenuated depletion of thiols following PGLYRP4 treatment. These effects were reversed by MK or reproduced by inhibiting MK synthesis. Deletion of cytochrome aa(3)-600 or NADH dehydrogenase (NDH) genes also increased B. subtilis resistance to PGLYRP4-induced killing and attenuated thiol depletion. PGLYRP4 treatment also inhibited B. subtilis respiration. Similarly in Escherichia coli, deletion of ubiquinone (UQ) synthesis, formate dehydrogenases (FDH), NDH-1, or cytochrome bd-I genes attenuated PGLYRP4-induced thiol depletion. PGLYRP4-induced low level of cytoplasmic membrane depolarization in B. subtilis and E. coli was likely not responsible for thiol depletion. Thus, our results show that the respiratory electron transport chain components, cytochrome aa(3)-600, MK, and NDH in B. subtilis, and cytochrome bd-I, UQ, FDH-O, and NDH-1 in E. coli, are required for both PGLYRP4-induced killing and thiol depletion and indicate conservation of the PGLYRP4-induced thiol depletion and killing mechanisms in Gram-positive and Gram-negative bacteria.202133420211
7872170.9922Quaternary ammonium compounds promoted anoxic sludge granulation and altered propagation risk of intracellular and extracellular antibiotic resistance genes. Surfactants could influence sludge morphology and disinfectants were linked to antibiotic resistance genes (ARGs). Thus, the response of activated sludge and ARGs to long-term quaternary ammonium compounds (QACs) exposure required further investigation, which is a popular surfactant and disinfectant. Here, three sequencing batch reactors were fed with 5 mg/L most frequently detected QACs (dodecyl trimethyl ammonium chloride (ATMAC C12), dodecyl benzyl dimethyl ammonium chloride (BAC C12) and didodecyl dimethyl ammonium chloride (DADMAC C12)) for 180 d. The long-term inhibitory effect on denitrification ranked: DADMAC C12 > BAC C12 > ATMAC C12. Besides, obvious granular sludge promoted by the increase of α-Helix/(β-Sheet + Random coil) appeared in DADMAC C12 system. Moreover, intracellular ARGs increased when denitrification systems encountered QACs acutely but decreased in systems chronically exposed to QACs. Although replication and repair metabolism in ATMAC C12 system was higher, ATMAC C12 significantly promoted proliferation of extracellular ARGs. It was noteworthy that the propagation risk of extracellular ARGs in sludge increased significantly during sludge granulation process, and intracellular sul2 genes in sludge and water both increased with the granular diameter in DADMAC C12 system. The universal utilization of QACs may enhance antibiotic resistance of bacteria in wastewater treatment plants, deserving more attention.202336444811
7888180.9922Microecology of aerobic denitrification system construction driven by cyclic stress of sulfamethoxazole. The construction of aerobic denitrification (AD) systems in an antibiotic-stressed environment is a serious challenge. This study investigated strategy of cyclic stress with concentration gradient (5-30 mg/L) of sulfamethoxazole (SMX) in a sequencing batch reactor (SBR), to achieve operation of AD. Total nitrogen removal efficiency of system increased from about 10 % to 95 %. Original response of abundant-rare genera to antibiotics was changed by SMX stress, particularly conditionally rare or abundant taxa (CRAT). AD process depends on synergistic effect of heterotrophic nitrifying aerobic denitrification bacteria (Paracoccus, Thauera, Hypomicrobium, etc). AmoABC, napA, and nirK were functionally co-expressed with multiple antibiotic resistance genes (ARGs) (acrR, ereAB, and mdtO), facilitating AD process. ARGs and TCA cycling synergistically enhance the antioxidant and electron transport capacities of AD process. Antibiotic efflux pump mechanism played an important role in operation of AD. The study provides strong support for regulating activated sludge to achieve in situ AD function.202438710419
8815190.9922Phosphorus-Solubilizing Bacteria Enhance Cadmium Immobilization and Gene Expression in Wheat Roots to Reduce Cadmium Uptake. The application of phosphorus-solubilizing bacteria is an effective method for increasing the available phosphorus content and inhibiting wheat uptake of heavy metals. However, further research is needed on the mechanism by which phosphorus-solubilizing bacteria inhibit cadmium (Cd) uptake in wheat roots and its impact on the expression of root-related genes. Here, the effects of strain Klebsiella aerogenes M2 on Cd absorption in wheat and the expression of root-related Cd detoxification and immobilization genes were determined. Compared with the control, strain M2 reduced (64.1-64.6%) Cd uptake by wheat roots. Cd fluorescence staining revealed that strain M2 blocked the entry of exogenous Cd into the root interior and enhanced the immobilization of Cd by cell walls. Forty-seven genes related to Cd detoxification, including genes encoding peroxidase, chalcone synthase, and naringenin 3-dioxygenase, were upregulated in the Cd+M2 treatment. Strain M2 enhanced the Cd resistance and detoxification activity of wheat roots through the regulation of flavonoid biosynthesis and antioxidant enzyme activity. Moreover, strain M2 regulated the expression of genes related to phenylalanine metabolism and the MAPK signaling pathway to enhance Cd immobilization in roots. These results provide a theoretical basis for the use of phosphorus-solubilizing bacteria to remediate Cd-contaminated fields and reduce Cd uptake in wheat.202439065516