Interaction of ciprofloxacin chlorination products with bacteria in drinking water distribution systems. - Related Documents




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774901.0000Interaction of ciprofloxacin chlorination products with bacteria in drinking water distribution systems. The interaction of ciprofloxacin chlorination products (CIP-CPs) with bacteria in drinking water distribution systems (DWDSs) was investigated. The piperazine ring of CIP was destroyed by chlorination. Among of CIP-CPs, by the bacterial role, 7.63% of the derivative with two carboxylic groups went through decarboxylation to form desethylene ciprofloxacin, and then loss of C(2)H(5)N group generated aniline compound. Furthermore, 12.3% of the aniline compound, 7.60% of chlorinated aniline compound and 1.35% of defluorinated product were bio-mineralized. Therefore, the chlorine and bacteria played synergistic effects on transformation of CIP-CPs in DWDSs, contributing to the obvious decrease of genotoxicity in effluents. Correspondingly, the TEQ(4-NQO) decreased from 667μg/L to 9.41μg/L. However, compared with DWDSs without CIP-CPs, the relative abundance of mexA and qnrS increased 1-fold in effluents and the relative abundance of qnrA and qnrB increased 3-fold in biofilms in DWDSs with CIP-CPs. mexA and qnrS positively correlated with Hyphomicrobium, Sphingomonas and Novosphingobium (p<0.05), while qnrA and qnrB positively correlated with Shewanella and Helicobacter (p<0.05), indicating the increase of antibiotic resistance genes (ARGs) came from the growth of these bacterial genera by transformation of CIP-CPs in DWDSs. These results suggested that biotransformation of antibiotics might increase ARGs risk in DWDSs.201728648729
804810.9992Ecological risks of sulfonamides and quinolones degradation intermediates: Toxicity, microbial community, and antibiotic resistance genes. The ecological risks posed by incompletely degraded antibiotic intermediates in aquatic environments warrant significant attention. This study investigated the degradation mechanisms of sulfonamides (sulfadiazine, sulfamethoxazole) and quinolones (ciprofloxacin, norfloxacin) during thermally activated persulfate (TAP) treatment. The main degradation mechanisms for sulfonamides involved S-N bond cleavage and -NH(2) oxidation mediated by sulfate and hydroxyl radicals, whereas quinolone degradation occurred primarily through piperazine ring cleavage facilitated by a single linear oxygen. Toxic degradation intermediates were found to be enriched with bacteria in real water samples, including Aeromonas (SDZ-50, 9.61%), Acinetobacter (SMZ-50, 21.91%), unclassified Archaea (CIP-50, 19.32%), and Herbaspirillum (NOR-50, 17.36%). Meanwhile, the abundance of sulfonamide-associated antibiotic resistance genes (ARGs) (sul1 and sul2) and quinolone-associated ARGs (mfpA, emrA, and lfrA) significantly increased, with SMZ-50 and NOR-50 reaching 659.34 and 2009.98 RPKM, respectively. Correlation analysis revealed differences in host diversity and composition driven by the same classes of antibiotics and their intermediates.202539662843
804620.9991Responses of aerobic granular sludge to fluoroquinolones: Microbial community variations, and antibiotic resistance genes. In this study, aerobic granular sludge (AGS) was operated under high levels of ammonium for removing three fluoroquinolones (FQs), i.e., ciprofloxacin (CFX), ofloxacin (OFX), and norfloxacin (NFX) at 3, 300, and 900 µg/L, respectively. Two key objectives were to investigate the differential distribution of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in sludge fractions and to evaluate correlations between ARGs and MGEs to nitrifying and denitrifying bacteria. AGS showed excellent stability under the exposure of FQs, with nitrite-oxidizing bacteria (NOB) more sensitive to FQs than ammonium-oxidizing bacteria (AOB). Specific oxygen utilization rates (SOUR) showed a reduction of 26.9% for NOB but only 4.0% of the reduced activity of AOB by 3 μg/L FQs. AGS performed better removal efficiencies for CFX and NFX than OFX, and the efficiencies increased with their elevated concentrations, except at 900 μg/L FQs. The elevated FQ concentrations led to a significant enrichment of intI1 and genus Thauera, while qnrD and qnrS showed no accumulation. Compared to nitrifiers, FQs relevant ARGs and the intI1 gene preferred to exist in denitrifiers, and the abundance of denitrifiers behaved a decreasing trend with the sludge size. Two quinoline-degrading bacteria were found in the AGS system, i.e., Alicycliphilus and Brevundimonas, possibly carrying qnrS and qnrD, respectively. Their relative abundance increased with the sludge size, which was 2.18% in sludge <0.5 mm and increased to 3.70% in sludge >2.0 mm, suggesting that the AGS may be a good choice in treating FQs-containing wastewater.202133676249
804530.9991Correlation among extracellular polymeric substances, tetracycline resistant bacteria and tetracycline resistance genes under trace tetracycline. Antibiotic resistance occurrences and proliferation in activated sludge have attracted more and more attention nowadays. However, the role which extracellular polymeric substance (EPS) plays on the antibiotic resistance is not clear. The changes and correlation among EPS, tetracycline (TC) resistant bacteria (TRB) and TC resistance genes (TRGs) of sequencing batch reactors (SBRs) were investigated. Performance of SBR without TC was compared with two other SBRs to which different amounts of TC were added. Total average EPS contents were found to increase significantly from 66 mg g−1 VSS to 181 mg g−1 VSS as the TC concentrations increased from 0 to 100 μg L−1. As the EPS content increased, TRB in sludge of the three SBRs increased significantly from 105 to 106 colony forming unit mL−1 after being exposed to TC. In addition, the concentrations of three groups of TRGs (copies mL−1) were determined by real-time fluorescence quantitative polymerase chain reaction and followed the order: efflux pump genes > ribosome protected genes > degradation enzyme genes. The numbers of TRGs in the idle stage were larger than those in the aeration sludge. Correlation coefficients (R2) between EPS and TRB in sludge were 0.823 (p < 0.01) while the correlation between EPS and total TRGs was poor (R2 = 0.463, p > 0.05). But it showed the same tendency that EPS and TRGs in sludge increased with the increasing of TC.201425461932
775040.9990Efficient removal of enrofloxacin in swine wastewater using eukaryotic-bacterial symbiotic membraneless bioelectrochemical system. A eukaryotic-bacterial symbiotic membraneless bioelectrochemical system (EBES) reactor with eukaryotic-bacteria symbiotic cathode was developed to treat swine wastewater containing enrofloxacin (ENR), which had high performance at ENR tolerance and operational stability. With ENR concentrations shifting from 2 to 50 mg/L, the removal efficiencies of ENR, chemical oxygen demand (COD) and NH(4)(+)-N always were higher than 95 %, and the maximum power output (≥343 mW/m(3)) could be achieved. At 20 mg/L ENR, the removal efficiencies of ENR, COD and NH(4)(+)-N respectively reached to 99.4 ± 0.1 %, 98.5 % ± 0.1 %, and 96.3 % ± 0.5 %, corresponding to the open circuit voltage and maximum power density (P(max)) of EBES were 851 mV and 455 mW/m(3). The community analyses showed that bacteria (Comamonas, Rhodobacter, Rhodococcus, and Vermiphilaceae et al.), algae (Chlorella) and fungi (Rozellomycota, Trebouxiophyceae, Exophiala, and Aspergillus et al.) at genus level were the dominate populations in the EBES, and their abundance increased with ENR concentration, suggesting they played key roles to remove ENR and another nutrient element. The low relative abundances (1.9 ×10(-7) to 1.1 ×10(-5) copies/g) of aac (6')-ib-cr, qnrA, qnrD, qnrS, and gyrA in effluent revealed that the present EBES reactor had superior capabilities in controlling antibiotic-resistance genes and antibiotic-resistant bacteria. Our trial experiments provided a novel way for antibiotic livestock wastewater treatment.202539938376
801150.9990Co-selective Pressure of Cadmium and Doxycycline on the Antibiotic and Heavy Metal Resistance Genes in Ditch Wetlands. Abuse of heavy metals and antibiotics results in the dissemination of metal resistance genes (MRGs) and antibiotic resistance genes (ARGs). Ditch wetlands are important sinks for heavy metals and antibiotics. The relationships between bacterial communities and MRG/ARG dissemination under dual stresses of heavy metals and antibiotics remain unclear. The responses of MRGs and ARGs to the co-selective pressure of cadmium (Cd) and doxycycline (DC) in ditch wetlands were investigated after 7-day and 84-day exposures. In ecological ditches, residual rates of Cd and DC varied from 0.4 to -5.73% and 0 to -0.61%, respectively. The greatest total relative abundance of ARGs was observed in the Cd 5 mg L(-1) + DC 50 mg L(-1) group. A significant level of DC (50 mg L(-1)) significantly reduced the total relative abundances of MRGs at a concentration of 5 mg L(-1) Cd stress. Redundancy analysis indicated that Cd and DC had strong positive effects on most ARGs and MRGs after a 7-day exposure. Meanwhile, the class 1 integron gene (intI1) exhibited strong positive correlations with most ARGs and cadmium resistance genes (czcA) after an 84-day exposure. Network analysis showed that Acinetobacter and Pseudomonas were the potential dominant host genera for ARGs and MRGs, and tetracycline resistance genes (tetA), czcA, and intI1 shared the same potential host bacteria Trichococcus after an 84-day exposure.202235250936
804260.9990Algal-bacterial consortium mediated system offers effective removal of nitrogen nutrients and antibiotic resistance genes. The sulfonamide antibiotic resistance genes (ARGs) especially sul1 was identified as the dominant in eutrophic water. The performance of Chlorella vulgaris-B. licheniformis consortium toward sul1 removal, total nitrogen (TN) removal, and the mechanism of sul1 removal was investigated. The removal efficiency of exogenous ARGs plasmids carrying sul1 reached (97.2 ± 2.3)%. The TN removal rate reached (98.5 ± 1.2)%. The enhancements of carbon metabolism, nitrogen metabolism, aminoacyl-tRNA biosynthesis, and glycoproteins had significant influences on sul1 and TN removals, under the premise of normal growth of algae and bacteria. The quantitative polymerase chain reaction (qPCR) results suggested that the absolute abundances of sul1 were low in algal-bacterial systems (0 gene copies/mL) compared with individual systems ((1 × 10(6) ± 15) gene copies/mL). The duplication of sul1 was inhibited in algal cells and bacterial cells. The algal-bacterial consortium seems to be a promising technology for wastewater treatment with a potential to overcome the eutrophication and ARGs challenges.202236049708
779570.9990Factors influencing the removal of antibiotic-resistant bacteria and antibiotic resistance genes by the electrokinetic treatment. The performance of the electrokinetic remediation process on the removal of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) was evaluated with different influencing factors. With chlortetracycline (CTC), oxytetracycline (OTC), and tetracycline (TC) as template chemicals, the removal of both ARB and ARGs was enhanced with the increase of voltage gradient (0.4-1.2 V cm(-1)) and prolonged reaction time (3-14 d). The greatest removal (26.01-31.48% for ARB, 37.93-83.10% for ARGs) was obtained applying a voltage of 1.2 V cm(-1), leading to the highest electrical consumption. The effect of polarity reversal intervals on the inactivation ratio of ARB followed the order of 0 h (66.06-80.00%) > 12 h (17.07-24.75%) > 24 h (10.44-13.93%). Lower pH, higher current density, and more evenly-distributed voltage drop was observed with a polarity reversal interval of 12 h compared with that of 24 h, leading to more efficient electrochemical reactions in soil. Compared with sul genes, tet genes were more vulnerable to be attacked in an electric field. It was mainly attributed to the lower abundance of tet genes (except tetM) and the varied effects of electrokinetic remediation process on different ARGs. Moreover, a relatively less removal ratio of tetC and tetG was obtained mainly due to the mechanism of the efflux pump upregulation. Both tet and sul genes were positively correlated with TC-resistant bacteria. The efflux pump genes like tetG and the cellular protection genes like tetM showed different correlations with ARB. This study enhances the current understanding on the removal strategies of ARB and ARGs, and it provides important parameters for their destruction by the electrokinetic treatment.201829807293
779480.9990Fate of antibiotic resistant bacteria and genes during wastewater chlorination: implication for antibiotic resistance control. This study investigated fates of nine antibiotic-resistant bacteria as well as two series of antibiotic resistance genes in wastewater treated by various doses of chlorine (0, 15, 30, 60, 150 and 300 mg Cl2 min/L). The results indicated that chlorination was effective in inactivating antibiotic-resistant bacteria. Most bacteria were inactivated completely at the lowest dose (15 mg Cl2 min/L). By comparison, sulfadiazine- and erythromycin-resistant bacteria exhibited tolerance to low chlorine dose (up to 60 mg Cl2 min/L). However, quantitative real-time PCRs revealed that chlorination decreased limited erythromycin or tetracycline resistance genes, with the removal levels of overall erythromycin and tetracycline resistance genes at 0.42 ± 0.12 log and 0.10 ± 0.02 log, respectively. About 40% of erythromycin-resistance genes and 80% of tetracycline resistance genes could not be removed by chlorination. Chlorination was considered not effective in controlling antimicrobial resistance. More concern needs to be paid to the potential risk of antibiotic resistance genes in the wastewater after chlorination.201525738838
804790.9990Simultaneous elimination of antibiotics and antibiotics resistance genes in nitritation of source-separated urine. Antibiotics in human urine could accelerate dissemination of antibiotics resistance genes (ARGs), posing potential threat to sewage. The nitritation of source-separated urine was a critical step to realize the urine resourcelization and nitrogen stabilization. However, the synergic control on antibiotics and ARGs during urine nitritation was unrevealed. This study investigated the removal profiles of five typical antibiotics and the shifts of microbial community and ARGs during stable nitritation. The result showed that sulfamethoxazole and roxithromycin were effectively eliminated with high removal efficiency of (95 ± 5) % and (90 ± 10) %, followed by enrofloxacin with removal efficiency of (60 ± 5) %, whereas trimethoprim and chloramphenicol showed low removal efficiency of less than 40 %. Ammonia oxidation bacteria and heterotrophic bacteria equally contributed to elimination of sulfamethoxazole with a high biodegradation rate of 0.1534 L/gVSS·h, while sorption and biodegradation jointly promoted other antibiotics removal. The total relative abundance of top 25 bacteria genera was decreased by 10 %. The total relative abundance of top 30 ARGs was decreased by more than 20 %, which was corresponding to the variation of bacterial community. The findings in this research would get a deeper insight into the eliminating antibiotics and controlling ARGs dissemination during nitritation of source-separated urine.202235897182
7951100.9990Proliferation of antibiotic resistance genes in microbial consortia of sequencing batch reactors (SBRs) upon exposure to trace erythromycin or erythromycin-H2O. A variety of antibiotics and their metabolites at sub-inhibitory level concentrations are suspected to expand resistance genes in the environment. However, knowledge is limited on the causal correlation of trace antibiotics or their metabolites with resistance proliferation. In this study, erythromycin (ERY) resistance genes were screened on microbial consortia of sequencing batch reactors (SBRs) after one year acclimation to ERY (100 μg/L) or dehydrated erythromycin (ERY-H(2)O, 50 μg/L). The identified esterase gene ereA explains that ERY could be degraded to six products by microbes acclimated to ERY (100 μg/L). However, ERY could not be degraded by microbes acclimated to ERY-H(2)O (50 μg/L), which may be due to the less proliferated ereA gene. Biodegradation of ERY required the presence of exogenous carbon source (e.g., glucose) and nutrients (e.g., nitrogen, phosphorus) for assimilation, but overdosed ammonium-N (>40 mg/L) inhibited degradation of ERY. Zoogloea, a kind of biofilm formation bacteria, became predominant in the ERY degradation consortia, suggesting that the input of ERY could induce biofilm resistance to antibiotics. Our study highlights that lower μg/L level of ERY or ERY-H(2)O in the environment encourages expansion of resistance genes in microbes.201121482429
7793110.9990Treatment of pharmaceutical wastewater by ionizing radiation: Removal of antibiotics, antimicrobial resistance genes and antimicrobial activity. In present study, the treatment of real pharmaceutical wastewater from an erythromycin (ERY) production factory by gamma irradiation was investigated. Results showed that a variety of antimicrobial resistance genes (ARGs), involving MLSB, tet, bla, multidrug, sul, MGEs and van genes and plentiful 9 bacterial phyla were identified in the raw wastewater. In addition to ERY, sulfamethoxazole (SMX) and tetracycline (TC) were also identified with the concentration of 3 order of magnitude lower than ERY. Results showed that the abatement of ARGs and antibiotics was much higher than that of antimicrobial activity and COD. With the absorbed dose of 50 kGy, the removal percentage of ARGs, ERY, antimicrobial activity and COD was 96.5-99.8%, 90.0%, 47.8% and 10.3%, respectively. The culturable bacteria were abated fast and completely at 5.0 kGy during gamma irradiation. The genus Pseudomonas was predominant in raw wastewater (56.7%) and its relative abundance decreased after gamma irradiation, to 1.3% at 50 kGy. With addition of peroxymonosulfate (PMS, 50 mM), the antimicrobial activity disappeared completely and ERY removal reached as high as 99.2% at the lower absorbed dose of 25 kGy. Ionizing radiation-coupled technique is a potential option to treat pharmaceutical wastewater for reduction of antibiotics, ARGs and antimicrobial activity.202134088196
7960120.9990Diversity evolution of functional bacteria and resistance genes (CzcA) in aerobic activated sludge under Cd(II) stress. An activated sludge sequencing batch reactor (SBR) was used to treat divalent cadmium (Cd(II)) wastewater for 60 d to investigate the overall treatment performance, evolution of the bacterial community, and abundance of the Cd(II) resistance gene CzcA and shifts in its potential host bacteria. During stable operation with a Cd(II) concentration of 20 mg/L, the average removal efficiencies of Cd(II) and chemical oxygen demand (COD) were more than 85% and that of total phosphorus was greater than 70%, while the total nitrogen (TN) was only about 45%. The protein (PN) content in the extracellular polymeric substances (EPS) increased significantly after Cd(II) addition, while polysaccharides displayed a decreasing trend (p < 0.05), indicating that EPS prefer to release PN to adsorb Cd(II) and protect bacteria from damage. Three-dimensional fluorescence spectral analysis showed that fulvic acid-like substances were the most abundant chemical components of EPS. The addition of Cd(II) adversely affected most denitrifying bacteria (p < 0.05), which is consistent with the low TN removal. In addition, quantitative polymerase chain reaction analysis revealed that CzcA gene abundance decreased as the Cd(II) concentration increased, possibly because expression of the CzcA gene was inhibited by Cd(II) stress. The majority of CzcA gene sequences were carried by Pseudomonas, making it the dominant genus among Cd(II)-resistant bacteria.201931514000
7961130.9989Effect of tetracycline on ammonia and carbon removal by the facultative bacteria in the anaerobic digester of a sewage treatment plant. This study was conducted to see the effect of tetracycline on nitrogen assimilation and carbon removal in an anaerobic digester of a sewage plant. Samples of sewage were collected from an anaerobic digester sludge. Consortium of nitrogen assimilating bacteria were isolated from the sample and its ability to assimilate ammonia at different concentrations of tetracycline was measured along with carbon removal. The results indicate that while high concentrations of tetracycline of more than 100 mg/L delayed the growth of the bacteria, the resistant bacteria grew after a lag period and the removal of nitrogen and carbon was unaffected even at the highest tetracycline concentration of 250 mg/L tested in this study.201830025323
8019140.9989In-feed antibiotic use changed the behaviors of oxytetracycline, sulfamerazine, and ciprofloxacin and related antibiotic resistance genes during swine manure composting. The dynamics of oxytetracycline (OTC), sulfamerazine (SM1), ciprofloxacin (CIP) and related antibiotic resistance genes (ARGs) during swine manure composting were compared between manure collected from swine fed a diet containing these three antibiotics (T(D)) and manure directly spiked with these drugs (T(S)). The composting removal efficiency of OTC (94.9 %) and CIP (87.8 %) in the T(D) treatment was significantly higher than that of OTC (83.8 %, P <  0.01) and CIP (83.9 %, P <  0.05) in the T(S) treatment, while SM1 exhibited no significant difference (P >  0.05) between the two treatments. Composting effectively reduced the majority of ARGs in both T(D) and T(S) types of manure, especially tetracycline resistance genes (TRGs). Compared with the T(S) treatment, the abundance of some ARGs, such as tetG, qepA, sul1 and sul2, increased dramatically up to 309-fold in the T(D) treatment. The microbial composition of the composting system changed significantly during composting due to antibiotic feeding. Redundancy analysis suggested that the abundance of ARGs had a considerable impact on alterations in the physicochemical parameters (C/N, pH and temperature) and bacterial communities (Actinobacteria, Proteobacteria and Firmicutes) during the composting of swine manure.202133254754
8041150.9989Insights into the microalgae-bacteria consortia treating swine wastewater: Symbiotic mechanism and resistance genes analysis. This study investigated the effects of microalgae-bacteria consortia (MBC) (Chlorella pyrenoidosa-activated sludge (AS)) treating swine wastewater with low C/N ratios. After co-culture, the removal rates of NH(4)(+)-N and PO(4)(3-)-P increased by 53.84% and 43.52%. Furthermore, the sulfamethoxazole (SMX) degradation rates in MBC were slightly higher than in the activated sludge process. Interestingly, the absolute abundance of antibiotic resistance genes (ARGs) in effluent from MBC is relatively less than in the AS process. C. pyrenoidosa has a negative zeta potential that allows bacteria to adhere to its surface. The concentrations of carbohydrates and proteins in extracellular polymeric substance (EPS) of MBC dramatically increased compared with the AS process. At the phylum level, Proteobacteria, Bacteroidota, and Cyanobacteria were the main bacteria, while Ascomycota and Basidiomycota were the primary fungi in MBC. Overall, those findings lead to a better understanding of the swine wastewater containing antibiotic treatment by MBC.202235217162
8029160.9989Migration of antibiotic resistance genes and evolution of flora structure in the Xenopus tropicalis intestinal tract with combined exposure to roxithromycin and oxytetracycline. The intestinal flora is one of the most important environments for antibiotic resistance development, owing to its diverse mix of bacteria. An excellent medicine model organism, Xenopus tropicalis, was selected to investigate the spread of antibiotic resistance genes (ARGs) in the intestinal bacterial community with single or combined exposure to roxithromycin (ROX) and oxytetracycline (OTC). Seventeen resistance genes (tetA, tetB, tetE, tetM, tetO, tetS, tetX, ermF, msrA, mefA, ereA, ereB, mphA, mphB, intI1, intI2, intI3) were detected in the intestines of Xenopus tropicalis living in three testing tanks (ROX tanks, OTC tanks, ROX + OTC tanks) and a blank tank for 20 days. The results showed that the relative abundance of total ARGs increased obviously in the tank with single stress but decreased in the tank with combined stress, and the genes encoding the macrolide antibiotic efflux pump (msrA), phosphatase (mphB) and integron (intI2, intI3) were the most sensitive. With the aid of AFM scanning, DNA was found to be scattered short chain in the blank, became extended or curled and then compacted with the stress from a single antibiotic, and was compacted and then fragmented with combined stress, which might be the reason for the variation of the abundance of ARGs with stress. The ratio of Firmicutes/Bacteroides related to diseases was increased by ROX and OTC. The very significant correlation between intI2 and intI3 with tetS (p ≤ 0.001) hinted at a high risk of ARG transmission in the intestines. Collectively, our results suggested that the relative abundance of intestinal ARGs could be changed depending on the intestinal microbiome and DNA structures upon exposure to antibiotics at environmental concentrations.202235063519
7792170.9989Comparative removal of two antibiotic resistant bacteria and genes by the simultaneous use of chlorine and UV irradiation (UV/chlorine): Influence of free radicals on gene degradation. The research aimed to remove antibiotic resistance by the simultaneous use of UV irradiation and chlorine (UV/chlorine). The inactivations of tetracycline resistant bacteria (TRB) during chlorination, UV irradiation, and UV/chlorine was investigated and compared with those of amoxicillin resistant bacteria (AmRB). Similar examination was also conducted for comparing the removals of their resistant genes (i.e., tetM and blaTem). The removals of antibiotic resistance highly depended on chlorine doses and UV intensities. The sufficient chlorine dose (20 mg.L(-1)) in the chlorination and the UV/chlorine completely inactivated TRB and AmRB (>7.3 log), while the UV irradiation could not achieve the complete disinfection. Microorganisms resistant to different antibiotics exhibit different susceptibility to the disinfection processes. The removals of antibiotic resistant genes (i.e., tetM and blaTem) were more difficult than those of TRB and AmRB. The UV/chlorine was the greatest process for tetM and blaTem removals, followed by chlorination and UV irradiation, respectively. Chlorination decreased the tetM and blaTem by 0.40-1.45 log and 1.04-2.45 log, respectively. The blaTem gene was highly reactive to chlorine, compared with tetM. The UV irradiation caused the tetM and blaTem reductions by 0.32-0.91 log and 0.59-0.96 log, respectively. The UV/chlorine improved the tetM and blaTem removals by 0.98-3.20 log and 1.28-3.36 log, respectively. The •OH contributed to the fraction of tetM and blaTem removals by 48% and 19%, respectively. The effect of reactive chlorine species on the tetM and blaTem removals was minor. The pseudo 1st-order kinetic constants (k') for tetM and blaTem removals by the UV/chlorine were highest. The •OH enhanced the k' values by 120% and 20% for the tetM and blaTem removals, respectively. The study showed the potential use of UV/chlorine for controlling antibiotic resistance.202133059146
7203180.9989Removal of cephalexin and erythromycin antibiotics, and their resistance genes, by microalgae-bacteria consortium from wastewater treatment plant secondary effluents. Antibiotics have become a concern in the aquatic environments owing to the potential development of bacterial resistances. Thus, this study evaluated the removal of cephalexin (CEP) and erythromycin (ERY) from a local wastewater treatment plant (WWTP) effluent, mediated by microalgae-bacteria consortium. Likewise, the removal of correlated antibiotics resistance genes bla(TEM) and ermB was also assessed. The incubation results showed that the added concentrations of selected antibiotics did not restrain the consortium growth. Moreover, CEP and ERY were almost completely removed after the cultivation period, reaching total removals of 96.54% and 92.38%, respectively. The symbiotic interaction between microalgae and bacteria plays a role in the kinetics removal of CEP and ERY. The abundance of bla(TEM) and ermB was reduced by 0.56 and 1.75 logs, respectively. Lastly, our results suggest that technology based on natural microalgae-bacteria consortium could be a potential alternative to improve the quality of WWTP effluents.202134268682
8005190.9989Deciphering the fate of antibiotic resistance genes in norfloxacin wastewater treated by a bio-electro-Fenton system. The misuse of antibiotics has increased the prevalence of antibiotic resistance genes (ARGs), considered a class of critical environmental contaminants due to their ubiquitous and persistent nature. Previous studies reported the potentiality of bio-electro-Fenton processes for antibiotic removal and ARGs control. However, the production and fate of ARGs in bio-electro-Fenton processes triggered by microbial fuel cells are rare. In this study, the norfloxacin (NFLX) average residual concentrations within two days were 2.02, 6.07 and 14.84 mg/L, and the average removal efficiency of NFLX was 79.8 %, 69.6 % and 62.9 % at the initial antibiotic concentrations of 10, 20 and 40 mg/L, respectively. The most prevalent resistance gene type in all processes was the fluoroquinolone antibiotic gene. Furthermore, Proteobacteria was the dominant ARG-carrying bacteria. Overall, this study can provide theoretical support for the efficient treatment of high antibiotics-contained wastewater by bio-electro-Fenton systems to better control ARGs from the perspective of ecological security.202236252757