Antibiotic sulfadiazine degradation by persulfate oxidation: Intermediates dependence of ecotoxicity and the induction of antibiotic resistance genes. - Related Documents




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756601.0000Antibiotic 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
756510.9999Microalgae 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
790120.9999Responses 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
756030.9999The effect of bacterial functional characteristics on the spread of antibiotic resistance genes in Expanded Granular Sludge Bed reactor treating the antibiotic wastewater. To explore the fate and spreading mechanism of antibiotics resistance genes (ARGs) in antibiotics wastewater system, a laboratory-scale (1.47 L) Expanded Granular Sludge Bed (EGSB) bioreactor was implemented. The operating parameters temperature (T) and hydraulic retention time (HRT) were mainly considered. This result showed the removal of ARGs and COD was asynchronous, and the recovery speed of ARGs removal was slower than that COD removal. The decreasing T was attributed to the high growth rate of ARGs host bacteria, while the shortened HRT could promote the horizontal and vertical gene transfer of ARGs in the sludge. The analysis result of potential bacterial host showed more than half of the potential host bacteria carried 2 or more ARGs and suggested an indirect mechanism of co-selection of multiple ARGs. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was used to investigate the functional characteristics of bacterial community. This result showed the bacterial functional genes contributed 40.41% to the abundance change of ARGs in the sludge, which was higher that of bacterial community. And the function genes of "aromatic hydrocarbon degradation", "Replication, recombination and repair proteins" and "Flagellar assembly" were mainly correlated with the transfer of ARGs in the sludge. This study further revealed the mechanism of ARGs spread in the EGSB system, which would provide new ideas for the development of ARGs reduction technology.202134488144
856740.9998System-dependent divergence of microbial community and resistome in two anaerobic niches under sulfamethoxazole selection. The prevalence of sulfamethoxazole (SMX) in high-strength wastewater poses a significant threat to the stability and efficiency of anaerobic biological treatment systems, particularly when deployed as initial treatment units. However, the complex interactions arising from SMX biodegradation and their resultant effects on typical anaerobic digestion (AD) and sulfate-reducing (SR) systems are not thoroughly understood. This study revealed that SMX exposure stimulated methanogenesis in the AD system and sulfate reduction in the SR system, driven primarily by enriched key functional taxa (e.g., methanogens, sulfate-reducing bacteria). Organic matter removal efficiency increased significantly in the AD system under SMX stress, attributed to the enrichment of fermentative bacteria. Notably, the enriched class Actinomycetes was capable of SMX biodegradation, thereby likely mitigating SMX stress for other microorganisms. In contrast, the SR system exhibited significantly diminished organic matter removal despite developing a more functionally specialized community under SMX exposure. This community harbored fewer SMX degraders, perpetuating selective pressure on the microbiota. Increasing SMX concentrations failed to induce significant shifts in overall community structure in either system, while significantly promoted the proliferation of antibiotic resistance genes (ARGs), particularly pronounced in the SR system exhibiting high SMX accumulation. Moreover, mobile genetic elements mediated the horizontal transfer of the sulfonamide resistance gene sul1 and other co-occurring ARGs located on plasmids. This study provides novel insights into the convergent and divergent microbial responses in the AD and SR systems under SMX exposure, highlighting the dual effects (both stimulatory and inhibitory) of SMX on the functionality of these anaerobic systems.202541130171
791350.9998Response 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
790360.9998Effects 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
856370.9998Overlooked role of extracellular polymeric substances in antibiotic-resistance gene transfer within microalgae-bacteria system. Controlling the spread of antibiotic-resistance genes (ARGs) under antibiotic stress has become an increasingly urgent issue. Microalgae possess the capability to remove antibiotics while concurrently inhibiting ARGs. Microalgae-bacteria systems can produce significant quantities of extracellular polymeric substances (EPS). However, the roles of EPS in the spread of ARGs have not been sufficiently explored, resulting in an insufficient understanding of the contribution of each EPS component and a lack of analysis on the complex interactions between EPS and ARGs. This study systematically explored the overlooked role of EPS in the transmission of ARGs within microalgae-bacteria systems. The current results showed that the potential of the microalgae-bacteria system for treating antibiotic wastewater. The tightly bound-EPS (TB-EPS) can acquire the higher absolute abundances of ARGs compared with the loosely bound-EPS (LB-EPS). The correlation coefficient between polysaccharides and TB-EPS ARGs was higher than that between polysaccharides and LB-EPS ARGs. The gene patterns of LB-EPS closely clustered with those of TB-EPS, while intracellular ARG gene patterns differed from both TB-EPS and LB-EPS. Metagenomic analyses indicated that the relative abundances of sul1 and sul2 were considerably higher at the beginning stage compared to the end stage. The abundance of Achromobacter, increased by the end stage, aligning with its potential to produce exopolysaccharide. Additionally, the absolute abundance of genes encoding exopolysaccharides (nagB and galE) and conjugative transfer transcription regulator (traF), increased over time. These findings enhanced our comprehension of the significance of EPS on the fate of ARGs in microalgae-bacteria systems during the treatment of antibiotic-contaminated wastewater.202539879767
761480.9998Biodegradation of sulfamethoxazole by microalgae-bacteria consortium in wastewater treatment plant effluents. Sulfamethoxazole (SMX) has been commonly detected in wastewater treatment plant (WWTP) effluents. SMX and other antibiotics can be considered as environmental contaminants of emerging concern. Due to their toxicity effects and their potential for the development of bacterial resistance their presence in aquatic compartment becomes a threat to human health. This study evaluated the bioremediation of SMX in WWTP effluents using a tertiary treatment composed by microalgae-bacteria consortium under low intensity artificial LED illumination, and also the assessment of sulfonamide resistance gene (sul1). The removal of SMX from WWTP effluents were 54.34 ± 2.35%, in which the microalgae-bacteria consortium improves the removal performance of SMX. The main process of SMX removal can be attributed to the symbiotic biodegradation by bacteria due to the increase of oxygen released by the microalgae photosynthetic process. Therefore, the microalgae-bacteria consortium used in this study, demonstrated to be a promising alternative for bioremediation of SMX, with potential for removal others contaminants from wastewater effluent. However, the residual SMX and the relative abundance of antibiotics resistance genes (ARG) found in this study suggest that SMX contributes to selective pressure for ARG maintenance and proliferation in WWTP effluent. Thus, further studies to removal ARG from WWTP effluent are needed.202032836119
791290.9998Distinct 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
7980100.9998Effect 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
8592110.9998Effects 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
7617120.9998Ozone pretreatment of wastewater containing aromatics reduces antibiotic resistance genes in bioreactors: The example of p-aminophenol. Aromatic matters are widely present in wastewater, especially industrial wastewater, and may lead to a high abundance of antibiotic resistance genes (ARGs) in wastewater treatment bioreactors and stimulate horizontal transfers of ARGs. Here, we investigated a practical approach that applying ozone pretreatment to mitigate ARGs in bioreactors treating wastewater containing a typical aromatic pollutant, p-aminophenol (PAP). The results showed that ozone pretreatment could effectively reduce the aromaticity of wastewater, and the relative abundance of ARGs in the bioreactor fed with ozone treated wastewater decreased by over 70% compared to the control reactor. Multidrug, quinolone, mupirocin, polymyxin, aminoglycoside, glycopeptide, beta-lactam, and trimethoprim resistance genes were all reduced in the bioreactors receiving wastewater pretreated by ozone. Metagenomic analysis suggested that the reduction of ARGs could be attributed to the co-occurrence of ARGs and aromatic degradation genes in bacteria. Furthermore, we expanded our analysis to investigate 71 metagenomes from different environments, and the results indicated that the impact of aromatics on ARG abundance widely occurs in various ecosystems and confirmed that high levels of aromatics could lead to high abundance of ARGs. Taken together, our work confirmed that the aromatics played critical roles in selecting ARGs and proposed a feasible approach to reduce ARGs in wastewater treatment bioreactors.202032563772
7978130.9998Metagenomic 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
7564140.9998Formation, 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
7613150.9998Effect 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
7907160.9998Determination 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
7902170.9998Determination 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
7549180.9998Fate 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
8082190.9998Deciphering 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