Response of the partial denitrification coupled with anaerobic ammonia oxidation system to disinfectant residues stress. - Related Documents




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791301.0000Response of the partial denitrification coupled with anaerobic ammonia oxidation system to disinfectant residues stress. The extensive use of disinfectants, especially NaClO, has resulted in chlorine disinfectant residues entering and impairing the biological treatment system. This study combined with long-term stress and transient shock of chlorine residues to comprehensively evaluate the variations of nitrogen removal performance, microbial community and antibiotic resistance genes composition in the PD/A system. The results showed that low concentration NaClO had no obvious harm to the system, but high concentration (>1 mg/L) NaClO would destroy the nitrogen removal performance of PD/A system. Interestingly, microorganisms in biofilm were more resistant to chlorine residues than that in sludge. Anaerobic ammonia oxidizing bacteria suffered more harm than denitrifying microorganisms, and chlorine residues mainly inhibited the process of converting N(2)H(4) to N(2) in anammox reaction. In addition, this study found that sludge showed a more significant increase in ARGs abundance and risk than biofilm. Moreover, risk assessments indicated that chlorine residues increased the risk of ARGs in PD/A systems.202540010223
791210.9999Distinct effects of hypochlorite types on the reduction of antibiotic resistance genes during waste activated sludge fermentation: Insights of bacterial community, cellular activity, and genetic expression. The effectiveness of hypochlorites (NaClO and Ca(ClO)(2)) on the reduction of antibiotic resistance genes (ARGs) during waste activated sludge (WAS) fermentation was determined by the quantitative PCR. NaClO and Ca(ClO)(2) exhibited distinct effects on ARGs fates. Ca(ClO)(2) was effective in removing all investigated ARGs, and the efficiency was highly dose-dependent. Unexpectedly, the NaClO treatment attenuated ARGs with lower efficiency and even caused the propagation of certain ARGs (i.e., aadA1 and tetQ) at higher doses. The extracellular polymeric substances dissolution and membrane integrity suggested that unstable NaClO had acute effects on bacteria initially, while it was ineffective to further attenuate ARGs released from hosts due to the rapid consumption of oxidative ClO(-). Without lasting and strong oxidative stress, the microbial activities of tolerant ARGs hosts will partially recover and then contribute to the ARGs dissemination across genera. In contrast, solid-state Ca(ClO)(2) was slowly released and exhibited prolonged effects on bacteria by disrupting cell membranes and removing the susceptible ARGs released from hosts. Furthermore, bacterial taxa-ARG network analysis indicated that Ca(ClO)(2) reduced the abundance of potential hosts, and the metabolic pathway and gene expression related to ARGs propagation were significantly downregulated by Ca(ClO)(2), which contributed to efficient ARGs attenuation.202133265039
756620.9998Antibiotic sulfadiazine degradation by persulfate oxidation: Intermediates dependence of ecotoxicity and the induction of antibiotic resistance genes. To preserve the water resources, this study has analyzed the ecotoxicity and antibiotic resistance genes (ARGs) induction capacity of sulfadiazine degradation intermediates resulting from persulfate activation oxidation enhanced by ultraviolet, ultrasound and microwave. The five degradation pathways caused by the contribution discrepancy of electron transfer and singlet oxygen ((1)O(2)) and variations in the ecotoxicity of different degradation products were analyzed. Microcosm experiment exhibited that the microbial community in actual water changed significantly with SDZ and degradation intermediates, in which the dominant genera were Aeromonas, Cupriavidus, Elizabethkingia and Achromobacter. Except for the selective pressure on bacteria, the degradation intermediates also exert a certain degree or even stronger induction on sulfonamide ARGs (sul4, sul1 and sul2) than SDZ. Furthermore, the potential hosts for sulfonamide ARGs were revealed by network analysis. These results provide a better understanding of antibiotics degradation mechanism and ARGs occurrence, which is useful for controlling the spread of ARGs.202336372382
790330.9998Effects of zero-valent iron (ZVI) on nitrogen conversion, transformation of sulfamethoxazole (SMX) and abundance of antibiotic resistance genes (ARGs) in aerobic granular sludge process. Even after pre-treatment, livestock and poultry wastewater still contain high concentrations of ammonia and residual antibiotics. These could be removed economically using the aerobic granular sludge (AGS) process with zero-valent iron (ZVI). The interaction of antibiotics and nitrogen in this process needs to be clarified and controlled, however, to achieve good removal performance. Otherwise, antibiotics might generate transformation products (TPs) with higher toxicity and lead to the emergence of antibiotic-resistant bacteria carrying antibiotic resistance genes (ARGs), which could cause persistent toxicity and the risk of disease transmission to the ecological environment. This study investigated the impact of ZVI on AGS for nitrogen and sulfamethoxazole (SMX) removal. The results show that AGS could maintain good ammonia removal performance and that the existence of SMX had a negative impact on ammonia oxidation activities. ZVI contributed to an increase in the abundance of nitrite oxidation bacteria, denitrifying bacteria and the functional genes of nitrogen removal. This led to better total nitrogen removal and a decrease in N(2)O emission. Accompanied by biological nitrogen transformation, SMX could be transformed into 14 TPs through five pathways. ZVI has the potential to enhance transformation pathways with TPs of lower ecotoxicity, thereby reducing the acute and chronic toxicity of the effluent. Unfortunately, ZVI might enhance the abundance of sul1, sul2, and sul3 in AGS, which increases the risk of sulfonamide antibiotic resistance. In AGS, Opitutaceae, Xanthomonas, Spartobacteria and Mesorhizobium were potential hosts for ARGs. This study provides theoretical references for the interaction of typical antibiotics and nitrogen in the biological treatment process of wastewater and bioremediation of natural water bodies.202337832300
798040.9998Effect of dissolved biochar on the transfer of antibiotic resistance genes between bacteria. The spread of antibiotic resistance genes (ARGs) is a global environmental issue. Dissolved biochar is more likely to contact bacteria in water, producing ecological risks. This study explored the effects of dissolved biochar on ARGs transfer in bacteria. Conjugative transfer efficiency was significantly different following treatment with different types of dissolved biochar. Typically, humic acid-like substance in dissolved biochar can significantly improve the transfer efficiency of ARGs between bacteria. When the concentration of dissolved biochar was ≤10 mg biochar/mL, humic acid-like substance substantially promoted ARGs transfer. An increase in dissolved biochar concentration weakened the ARGs transfer from humic acid-like substance. The inhibitory effects of small-molecule matters dominated, decreasing conjugative transfer frequency. At a concentration of 100 mg biochar/mL, the conjugative transfer efficiency of all treatments was lower than that of control. Compared with corn straw dissolved biochar, there were more transconjugants in pine sawdust dissolved biochar. Following treatment with 10 mg biochar/mL pine sawdust dissolved biochar, the number of transconjugants was at its maximum; approximately 7.3 folds higher than the control. We also explored mechanisms by which dissolved biochar impacts conjugative transfer. Due to the complex composition of dissolved biochar, its effects on the expression of conjugative transfer-related genes were also dynamic. This study investigates the ecological risk of biochar and guides its scientific application.202134274650
790250.9998Determination of the lower limits of antibiotic biodegradation and the fate of antibiotic resistant genes in activated sludge: Both nitrifying bacteria and heterotrophic bacteria matter. Antibiotics can be biodegraded in activated sludge via co-metabolism and metabolism. In this study, we investigated the biodegradation pathways of sulfamethoxazole (SMX) and antibiotic resistant genes' (ARGs) fate in different autotrophic and heterotrophic microorganisms, by employing aerobic sludge, mixed sludge, and nitrifying sludge. A threshold concentration of SMX activating the degradation pathways in the initial stage of antibiotics degradation was found and proved in different activated sludge systems. Heterotrophic bacteria played an important role in SMX biodegradation. However, ammonia-oxidizing bacteria (AOB) had a faster metabolic rate, which was about 15 times higher than heterotrophic bacteria, contributing much to SMX removal via co-metabolism. As SMX concentration increases, the amoA gene and AOB relative abundance decreased in aerobic sludge due to the enrichment of functional heterotrophic bacteria, while it increased in nitrifying sludge. Microbial community analysis showed that functional bacteria which possess the capacity of SMX removal and antibiotic resistance were selected by SMX pressure. Potential ARGs hosts could increase their resistance to the biotoxicity of SMX and maintain system performance. These findings are of practical significance to guide antibiotic biodegradation and ARGs control in wastewater treatment plants.202234799165
789160.9998Co-selective effect of dissolved organic matter and chlorine on the bacterial community and their antibiotic resistance in biofilm of drinking water distribution pipes. The proliferation of pathogenic bacteria and antibiotic resistance genes (ARGs) in the biofilm of drinking water distribution pipes poses a serious threat to human health. This work adopted 15 polyethylene (PE) pipes to study the co-selective effect of dissolved organic matter (DOM) and chlorine on the bacterial community and their antibiotic resistance in biofilm. The results indicated that ozone and granular activated carbon (O(3)-GAC) filtration effectively removed lignins and proteins from DOM, and chlorine disinfection eliminated carbohydrate and unsaturated hydrocarbons, which both contributed to the inhibition of bacterial growth and biofilm formation. After O(3)-GAC and disinfection treatment, Porphyrobacter, unclassified_d_bacteria, and Sphingopyxis dominated in the biofilm bacterial community. Correspondingly, the bacterial metabolism pathways, including the phosphotransferase system, phenylalanine, tyrosine and tryptophan biosynthesis, ABC transporters, and starch and sucrose metabolism, were downregulated significantly (p < 0.05), compared to the sand filtration treatment. Under such a situation, extracellular polymeric substances (EPS) secretion was inhibited in biofilm after O(3)-GAC and disinfection treatment, postponing the interaction between EPS protein and pipe surface, preventing bacteria, especially pathogens, from adhering to the pipe surface to form biofilm, and restraining the spread of ARGs. This study revealed the effects of various water filtration and disinfection processes on bacterial growth, metabolism, and biofilm formation on a molecular level, and validated that the O(3)-GAC filtration followed by chlorine disinfection is an effective and promising pathway to control the microbial risk of drinking water.202539490093
790970.9998Simultaneous efficient removal of tetracycline and mitigation of antibiotic resistance genes enrichment by a modified activated sludge process with static magnetic field. To address the increasing issue of antibiotic wastewater, this study applied a static magnetic field (SMF) to the activated sludge process to increase the efficiency of tetracycline (TC) removal from swine wastewater and to reveal its enhanced mechanisms. The results demonstrated that the SMF-modified activated sludge process could achieve almost complete TC removal at sludge loading rates of 0.3 mg TC/g MLSS/d. Analysis of zeta potential and extracellular polymeric substances composition of the activated sludge revealed that SMF increased electrostatic interactions between TC and activated sludge and made activated sludge has much more binding sites, finally resulting in the increased TC biosorption. Metagenomic analysis showed that SMF promoted the enrichment of ammonia-oxidizing bacteria, TC-degrading bacteria, and aromatic compounds-degrading bacteria; it also enhanced ammonia monooxygenase- and cytochrome P450-mediated TC metabolism while upregulating functional genes associated with oxidase, reductase, and dehydrogenase - all contributing to increased TC biodegradation. Additionally, SMF mitigated the enrichment and spread of antibiotic resistance genes (ARGs) by decreasing the abundance of potential hosts of ARGs and inhibiting the upregulation of genes encoding ABC transporters and putative transposase. Based on these findings, this study demonstrates that magnetic field is an enhancement strategy with great potential to relieve the harmful impacts of the growing antibiotic wastewater problem on human health and the ecosystem.202439038424
790180.9998Responses of antibiotic resistance genes and microbial community in the microalgae-bacteria system under sulfadiazine: Mechanisms and implications. Microalgae-bacteria system is an emerging alternative for sustainable wastewater treatment. Exploring the structure and diversity of microbial community in microalgae-bacteria system under sulfadiazine stress can contribute to the understanding of the sulfadiazine behavior in environments. Furthermore, as important carriers of antibiotic resistance genes (ARGs), microalgae can influence the profiles of ARGs either directly or indirectly through the secretion of metabolites. However, the effects of sulfadiazine on ARGs dissemination of microalgae-bacteria systems remain underreported. Herein, the impacts of sulfadiazine (1 mg/L) on the structural diversity and metabolic activity of microorganisms were examined in microalgae-bacteria systems. Results showed that microalgae-bacteria system could remove NH(4)(+)-N better (about 72.3 %) than activated sludge system, and hydrolysis was the first step in sulfadiazine degradation. A high level of intI1 (5.7 × 10(4) copies/mL) was detected in the initial media of the microalgae-bacteria system. Microalgae could hamper the rate of horizontal gene transfer activation. Compared with activated sludge system, the abundance of sul genes (sul1, sul2, sul3, and sulA) was significantly lowered after treating with microalgae-bacteria system. Additionally, the number of proteins and the sum of polysaccharides in the extracellular polymeric substances of the activated sludge system were lower than those of the microalgae-bacteria system. Microalgae can alter microbial communities. The genus Rozellomycota predominated all samples. Fungi with relatively high abundance increased in the microalgae-bacteria system, including Dipodascaceae, Rhodotorula, and Geotrichum. These results offer valuable insights into the application processes involving microalgae-bacteria system.202540602895
804490.9998Effect of tetracycline on nitrogen removal in Moving Bed Biofilm Reactor (MBBR) System. The effect of tetracycline (TC) on nitrogen removal in wastewater treatment plants has become a new problem. This study investigated the effects of TC on nitrogen removal using a Moving Bed Biofilm Reactor system. The results showed that there was no significant effect on nitrogen removal performance when the concentration of TC was 5 mg/L, and that the total nitrogen (TN) removal efficiency could reach 75-77%. However, when the concentration of TC increased to 10 mg/L, the denitrification performance was affected and the TN removal efficiency decreased to 58%. The abundance of denitrifying bacteria such as those in the genus Thauera decreased, and TC-resistant bacteria gradually became dominant. At a TC concentration of 10 mg/L, there were also increases and decreases, respectively, in the abundance of resistance and denitrification functional genes. The inhibitory effect of TC on denitrification was achieved mainly by the inhibition of nitrite-reducing bacteria.202235007308
8512100.9998Dissolved oxygen facilitates efficiency of chlorine disinfection for antibiotic resistance. Controlling the dissemination of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) is a global concern. While commonly used chlorine disinfectants can damage or even kill ARB, dissolved oxygen (DO) may affect the formation of reactive chlorine species. This leads to the hypothesis that DO may play roles in mediating the effectiveness of chlorine disinfection for antibiotic resistance. To this end, this study investigated the impacts of DO on the efficiency of chlorine disinfection for antibiotic resistance. The results revealed that DO could increase the inactivation efficiency of ARB under chloramine and free chlorine exposure at practically relevant concentrations. Reactive species induced by DO, including H(2)O(2), O(2)(-), and OH, inactivated ARB strains by triggering oxidative stress response and cell membrane damage. In addition, the removal efficiency of extracellular ARGs (i.e. tetA and bla(TEM)) was enhanced with increasing dosage of free chlorine or chloramine under aerobic conditions. DO facilitated the fragmentation of plasmids, contributing to the degradation of extracellular ARGs under exposure to chlorine disinfectants. The findings suggested that DO facilitates disinfection efficiency for antibiotic resistance in water treatment systems.202438750753
7565110.9998Microalgae Enhances the Adaptability of Epiphytic Bacteria to Sulfamethoxazole Stress and Proliferation of Antibiotic Resistance Genes Mediated by Integron. The transmission of ARGs in the microalgae-associated epiphytic bacteria remains unclear under antibiotic exposure, apart from altering the microbial community structure. In this study, Chlorella vulgaris cocultured with bacteria screened from surface water was examined to explore the spread of ARGs in the presence of sulfamethoxazole (SMX). The extracellular polymers released by Chlorella vulgaris could reduce antibiotic-induced collateral damage to bacteria, thus increasing the diversity of the microalgae-associated epiphytic bacteria. The abundances of sul1 and intI1 in the phycosphere at 1 mg/L SMX dose increased by 290 and 28 times, respectively. Metagenomic sequencing further confirmed that SMX bioaccumulation stimulated the horizontal transfer of sul1 mediated by intI1 in the microalgae-associated epiphytic bacteria, while reactive oxygen species (ROS)-mediated oxidative stress induced the SOS response and thus enhanced the transformation of sul1 in the J group. This is the first study to verify that microalgae protect bacteria from antibiotic damage and hinder the spread of ARGs mediated by SOS response, while the transfer of ARGs mediated by integron is promoted due to the bioaccumulation of SMX in the phycosphere. The results contribute to present comprehensive understanding of the risk of ARG proliferation by the presence of emerging contaminants residues in river.202439417646
7978120.9998Metagenomic insight into the enrichment of antibiotic resistance genes in activated sludge upon exposure to nanoplastics. Activated sludge is an important reservoir for the co-occurring emerging contaminants including nanoplastics (NPs) and antibiotic resistance genes (ARGs). However, the impacts and potential mechanisms of NPs on the fate of ARGs in activated sludge are not fully understood. Herein, we used metagenomic approach to investigate the responses of ARGs, host bacteria, mobile genetic elements (MGEs), and functional genes to polystyrene (PS) NPs at environmentally relevant (0.5 mg/L) and high stress concentrations (50 mg/L) in activated sludge. The results showed that 0.5 and 50 mg/L PS NPs increased the relative abundance of ARGs in the activated sludge by 58.68% and 46.52%, respectively (p < 0.05). Host tracking analysis elucidated that the hosts of ARGs were significantly enriched by PS NPs (p < 0.05), with Proteobacteria being the predominant host bacteria. Additionally, the occurrence of new ARGs hosts and the enrichment of MGEs and functional genes (i.e., genes related to SOS response, cell membrane permeability, and secretion system, etc.) indicated that PS NPs promoted horizontal gene transfer (HGT) of ARGs. Finally, path modeling analysis revealed that the proliferation of ARGs caused by PS NPs was primarily attributed to the enhancement of HGT and the enrichment of host bacteria. Our findings contribute to a comprehensive understanding of the spread risk of ARGs in activated sludge under NPs pollution.202439510298
7549130.9998Fate of antibiotic resistance genes during sludge anaerobic fermentation: Roles of different sludge pretreatment. Excess sludge, the primary by-product of wastewater treatment plants, is the source and sink of antibiotic resistance genes (ARGs). Sludge pretreatments are an indispensable pathway to improve the resource recovery and harmfulness for anaerobic digestion sludge. However, fewer studies have compared the effects of different pretreatment technologies on the distribution of ARGs during anaerobic sludge digestion. Here, this study established seven anaerobic digesters, and four typical ARGs and one integrase gene of class 1 integron (intI1) regarded as the representative mobile genetic elements (MGEs) were examined during the whole anaerobic digestion process. It was found anaerobic digestion could effectively remove ARGs with about 70.86% removal rate of total ARGs. Among these pretreatments, the reduce efficiency of ARGs was the highest in 50 °C pretreatment, followed by oxidant, and the last was acid-alkaline. The microbial community analysis demonstrated the microbial community structure, including ARGs hosts and antibiotic resistant bacteria, was significantly changed and influenced by high temperature pretreatment. In addition, high temperature and K(2)S(2)O(8) observably decrease the level of ROS production. Macro transcriptome analysis indicated that sludge pretreatment, except for 50 °C pretreatment, up-regulated the genes relevant to lyases and transferase, but down-regulated the genes responsible for peroxidase, antioxidant enzymes and T4SS gene. This study emphasized and compared the different sludge pretreatments on the fate of ARGs in anaerobic sludge, and highlighted concerns regarding the environmental and health risks to our society.202439393457
7613140.9998Effect of bio-electrochemical system on the fate and proliferation of chloramphenicol resistance genes during the treatment of chloramphenicol wastewater. Bioelectrochemical systems can effectively degrade antibiotics, but there is the need to better understand the fate of antibiotic resistance bacteria and antibiotic resistance genes during the bioelectrochemical degradation of antibiotics. In this study, a BES was developed as a platform to investigate the fate of chloramphenicol resistance bacteria (CRB) and the expression of chloramphenicol resistance genes (CRGs) under different operating conditions during chloramphenicol biodegradation. The results indicated that chloramphenicol was effectively removed and chloramphenicol removal efficiency could be improved under less chloramphenicol concentration and more negative cathode potential. Higher chloramphenicol concentration enhanced the enrichment of CRB and expression of CRGs. Furthermore, the abundances of CRB were enhanced under more negative cathode potential, the expression of CRGs under less negative cathode potential were induced. However, both the enrichment of CRB and expression of CRGs could be moderated under a medium cathode potential. This result could provide the scientific reference for research about the fate of antibiotic resistance genes in bioelectrochemical systems.201728390239
7907150.9998Determination of the fate of antibiotic resistance genes and the response mechanism of plants during enhanced antibiotic degradation in a bioelectrochemical-constructed wetland system. Chloramphenicol (CAP) has a high concentration and detection frequency in aquatic environments due to its insufficient degradation in traditional biological wastewater treatment processes. In this study, bioelectrochemical assistant-constructed wetland systems (BES-CWs) were developed as advanced processes for efficient CAP removal, in which the degradation and transfer of CAP and the fate of antibiotic resistance genes (ARGs) were evaluated. The CAP removal efficiency could reach as high as 90.2%, while the removed CAP can be partially adsorbed and bioaccumulated in plants, significantly affecting plant growth. The vertical gene transfer and horizontal gene transfer increased the abundance of ARGs under high voltage and CAP concentrations. Microbial community analysis showed that CAP pressure and electrical stimulation selected the functional bacteria to increase CAP removal and antibiotic resistance. CAP degradation species carrying ARGs could increase their opposition to the biotoxicity of CAP and maintain system performance. In addition, ARGs are transferred into the plant and upward, which can potentially enter the food chain. This study provides an essential reference for enhancing antibiotic degradation and offers fundamental support for the underlying mechanism and ARG proliferation during antibiotic biodegradation.202336931217
8082160.9998Deciphering the toxic effects of antibiotics on denitrification: Process performance, microbial community and antibiotic resistance genes. The extensive application of antibiotics, and the occurrence and spread of antibiotic resistance genes (ARGs) shade health risks to human and animal. The long-term effects of sulfamethoxazole (SMX) and tetracycline (TC) on denitrification process were evaluated in this study, with the focus on nitrogen removal performance, microbial community and ARGs. Results showed that low-concentration SMX and TC (<0.2 mg L(-1)) initially caused a deterioration in nitrogen removal performance, while higher concentrations (0.4-20 mg L(-1)) of both antibiotics had no further inhibitory influences. The abundances of ARGs in both systems generally increased during the whole period, and most of them had significant correlations with intI1, especially efflux-pump genes. Castellaniella, which was the dominant genus under antibiotic pressure, might be potential resistant bacteria. These findings provide an insight into the toxic effects of different antibiotics on denitrification process, and guides future efforts to control antibiotics pollution in ecosystems.202032250829
8592170.9998Effects of persulfate treatment on the fates of antibiotic resistance genes in waste activated sludge fermentation process and the underlying mechanism. The occurrence of antibiotic resistance genes (ARGs) in waste activated sludge (WAS) fermentation was investigated with persulfate (PS)-based treatment. ARGs affiliated with multidrug (mexP), macrolide (bla(OXA-129)), tetracycline (tetB), sulfonamide (sul1), and vancomycin (vanRG) types were significantly decreased by PS/Fe treatment. Mechanistic investigations revealed that PS/Fe possessed oxidating potential and exhibited devastating effects on WAS fermentation. First, PS/Fe promoted cell structure damage, which facilitated ARGs release from potential hosts. A co-occurrence network analysis indicated that Fe/PS suppressed the proliferation of potential host bacteria. In addition, the PS/Fe treatment induced the decreased abundance of certain functional genes involved in pathways associated with ARGs dissemination. Finally, variation partitioning analysis demonstrated that the microbial community structure exhibited more vital effects on ARGs fates than physicochemical factors (i.e., pH and ORP) and gene expression (i.e., two-component system). This work provided a deeper understanding of the critical factors used to determine ARGs fates during WAS fermentation.202234864181
7564180.9998Formation, characteristics and microbial community of aerobic granular sludge in the presence of sulfadiazine at environmentally relevant concentrations. The growing occurrence of antibiotics in water environment is causing increasing concern. To investigate the impact of frequently detected sulfadiazine on the formation of aerobic granular sludge, four sequencing batch reactors (SBRs) were set up with different environmentally relevant concentrations of sulfadiazine. Results showed that sulfadiazine pressure could lead to larger and more compact sludge particles and cause slight effect on reactor performance. Presence of sulfadiazine apparently increased the extracellular polymeric substances (EPS) secretion of microorganisms. Quantitative polymerase chain reaction (qPCR) showed that the abundances of sulfanilamide resistance genes in sludge increased with addition of sulfadiazine significantly. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was used to predict functional genes, results showed that sulfadiazine led to an increase of specific functional genes. Thereby, it concluded that microorganisms could change the community structure by acclimating of functional bacteria and antibiotic resistance species to adapt to the antibiotic stress.201829197771
7910190.9998Tetracycline degradation by a mixed culture of halotolerant fungi-bacteria under static magnetic field: Mechanism and antibiotic resistance genes transfer. Efficient antibiotics removal lowers the transmission risk of antibiotic resistance genes (ARGs). However, low efficiency limits the application of biological methods for antibiotics removal. Herein, a mixed culture of halotolerant fungi-bacteria was used for treatment of saline wastewater containing tetracycline (TC). Furthermore, static magnetic field (SMF) was used to increase TC removal. The study examined the effectiveness of SMF in removing antibiotics from saline wastewater and the associated risk of ARGs transmission. The results demonstrated that the application of a 40 mT SMF significantly improved the TC removal efficiency by 37.09 %, compared to the control (SMF=0) The TC was mainly removed through biodegradation and adsorption. In biodegradation, SMF enhanced electron transport system activity, and activities of lignin-degrading enzymes which led to higher TC biodegradation. The activity of lactate dehydrogenase and malondialdehyde decreased, lowering the damage of microbial cell membranes by TC. During the adsorption process, higher generation of extracellular polymeric substances was observed under SMF, which caused an increase in TC removal via adsorption. Microbial community analysis revealed that SMF facilitated the enrichment of TC-degrading microorganisms. Under SMF, vertical gene transfer of ARGs increased, while horizontal gene transfer risk decreased due to a reduction in mobile genetic elements (intl1) abundance. This study demonstrates that SMF is a promising strategy for enhancing TC removal efficiency, providing a basis for improved antibiotic wastewater management.202540199074