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786300.9981Mechanisms on the removal of gram-negative/positive antibiotic resistant bacteria and inhibition of horizontal gene transfer by ferrate coupled with peroxydisulfate or peroxymonosulfate. The existence of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) has been a global public environment and health issue. Due to the different cell structures, gram-positive/negative ARB exhibit various inactivation mechanisms in water disinfection. In this study, a gram-negative ARB Escherichia coli DH5α (E. coli DH5α) was used as a horizontal gene transfer (HGT) donor, while a gram-positive ARB Bacillus as a recipient. To develop an efficient and engineering applicable method in water disinfection, ARB and ARGs removal efficiency of Fe(VI) coupled peroxydisulfate (PDS) or peroxymonosulfate (PMS) was compared, wherein hydroxylamine (HA) was added as a reducing agent. The results indicated that Fe(VI)/PMS/HA showed higher disinfection efficiency than Fe(VI)/PDS/HA. When the concentration of each Fe(VI), PMS, HA was 0.48 mM, 5.15 log E. coli DH5α and 3.57 log Bacillus lost cultivability, while the proportion of recovered cells was 0.0017 % and 0.0566 %, respectively, and HGT was blocked. Intracellular tetA was reduced by 2.49 log. Fe(IV) and/or Fe(V) were proved to be the decisive reactive species. Due to the superiority of low cost as well as high efficiency and practicality, Fe(VI)/PMS/HA has significant application potential in ARB, ARGs removal and HGT inhibition, offering a new insight for wastewater treatment.202438615644
780710.9980Copper oxide/peroxydisulfate system for urban wastewater disinfection: Performances, reactive species, and antibiotic resistance genes removal. In this study, copper oxide (CuO) catalyzed peroxydisulfate (PDS) system was investigated for the inactivation of a broad range of pathogenic microorganisms from urban wastewater. Complete inactivation of Escherichia coli, Enterococcus, F-specific RNA bacteriophages from secondary treated wastewater was achieved after a short time (15-30 min) treatment with CuO (10 g/L)/PDS (1 mM) system, but spores of sulfite-reducing bacteria took 120 min. No bacterial regrowth occurred during storage after treatment. Significant reduction of the pathogens was explained by the generation of the highly selective Cu(III) oxidant, as the predominant reactive species, which could quickly oxidize guanine through a one-electron oxidation pathway. Additionally, the potential of the CuO (10 g/L)/PDS (1 mM) system to inactivate antibiotic-resistant bacteria and antibiotic resistance genes (ARB&Gs) was explored. Sulfamethoxazole-resistant E. coli was used as the model ARB and a 3.2 log of reduction was observed after 10 min of treatment. A considerable reduction (0.7-2.3 log) of selected ARGs including blaTEM, qnrS, emrB, sul1, and genes related to the dissemination of antibiotic resistance, including the Class 1 integron-integrase (intI1), and the insertion sequence (IS613) was achieved after 60 min treatment. All these findings indicated the promising applicability of the CuO/PDS system as a disinfection technology for wastewater reuse in agriculture.202234648831
780820.9980Visible light-driven C/O-g-C(3)N(4) activating peroxydisulfate to effectively inactivate antibiotic resistant bacteria and inhibit the transformation of antibiotic resistance genes: Insights on the mechanism. Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) dissemination within water pose a serious threat to public health. Herein, C and O dual-doped g-C(3)N(4) (C/O-g-C(3)N(4)) photocatalyst, fabricated via calcination treatment, was utilized to activate peroxydisulfate (PDS) to investigate the disinfection effect on tetracycline-resistant Escherichia coli and the transformation frequency of ARGs. As a result, approximately 7.08 log E. coli were inactivated, and 72.36 % and 53.96 % of antibiotics resistance gene (tetB) and 16 S rRNA were degraded respectively within 80 min. Futhermore, the transformation frequency was reduced to 0.8. Characterization and theoretical results indicated that C and O doping in g-C(3)N(4) might lead to the electronic structure modulation and band gap energy reduction, resulting in the production of more free radicals. The mechanism analysis revealed that C/O-g-C(3)N(4) exhibited a lower adsorption energy and reaction energy barrier for PDS compared to g-C(3)N(4). This was beneficial for the homolysis of O-O bonds, forming SO(4)(•-) radicals. The attack of the generated active species led to oxidative stress in cells, resulting in damage to the electron transport chain and inhibition of ATP production. Our findings disclose a valuable insight for inactivating ARB, and provide a prospective strategy for ARGs dissemination in water contamination.202437976858
779030.9980Disinfection of polymicrobial urines by electrochemical oxidation: Removal of antibiotic-resistant bacteria and genes. In this work, data obtained from the University Hospital Complex of Albacete (Spain) were selected as a case study to carry out the disinfection experiments. To do this, different configurations of electrochemical reactors were tested for the disinfection of complex urines. Results showed that 4-6 logs bacterial removal were achieved for every bacterium tested when working with a microfluidic flow-through reactor after 180 min (0.423 Ah dm(-3)). The MIKROZON® cell reached a total disinfection after 60 min (1.212 Ah dm(-3)), causing severe damages induced in the cell walls observed in SEM images. The concentration profiles of the electrogenerated disinfectants in solution could explain the differences observed. Additionally, a mean decrease in the ARGs concentration ranked as follows: bla(KPC) (4.18-logs) > bla(TEM) (3.96-logs) > ermB (3.23-logs) using the MIKROZON® cell. This electro-ozonizer could be considered as a suitable alternative to reduce the risk of antibiotic resistance spread. Hence, this study provides an insight into different electrochemical reactors for the disinfection of complex hospital urine matrices and contributes to reduce the spread of antibiotic resistance through the elimination of ARGs. A topic of great importance nowadays that needs to be further studied.202234923384
778740.9979Inactivation of a pathogenic NDM-1-positive Escherichia coli strain and the resistance gene bla(NDM-1) by TiO(2)/UVA photocatalysis. Proliferation of bla(NDM-1) in water and wastewater is particularly concerning because of multidrug-resistance and horizontal transfer of the gene. In the present study, a pathogenic NDM-1-positive Escherichia coli strain (named E. coli NDM-1) and the bla(NDM-1) gene were treated with titanium dioxide (TiO(2))/ultraviolet A (UVA) photocatalysis. Effects of catalyst dose, UVA intensity, and phosphate on bacteria and intracellular and extracellular bla(NDM-1) genes were determined. With increases in TiO(2) dose and UVA intensity, the inactivation rate of E. coli NDM-1 increased greatly in saline solution. However, phosphate in water hindered adsorption of bacteria to TiO(2) and partly changed the TiO(2) photocatalytic pathway, resulting in low degradation efficiency. Although inactivation of E. coli NDM-1 was highly efficient, TiO(2)/UVA photocatalysis had little effect on removal of the bla(NDM-1) gene. During the 2-h photocatalytic experiments, E. coli cells decreased by 4.7-log, while the bla(NDM-1) gene decreased by 0.7- ~ 1.5-log. Moreover, the degradation rate of extracellular bla(NDM-1) was ~2.7 times higher than that of intracellular genes. Abundance and transformation frequency of residual bla(NDM-1) genes remained high, even when bacteria were completely inactivated, indicating potential health risks. Increases in treatment time and UVA irradiation intensity are needed to remove the bla(NDM-1) gene to sufficiently low levels.202235842147
786650.9979Inactivation of sulfonamide antibiotic resistant bacteria and control of intracellular antibiotic resistance transmission risk by sulfide-modified nanoscale zero-valent iron. The inactivation of a gram-negative sulfonamide antibiotic resistant bacteria (ARB) HLS.6 and removal of intracellular antibiotic resistance gene (ARG, sul1) and class I integrase gene (intI1) by nanoscale zero-valent iron (nZVI) and sulfide-modified nZVI (S-nZVI) with different S/Fe molar ratios were investigated in this study. The S-nZVI with high sulfur content (S/Fe = 0.05, 0.1, 0.2) was superior to nZVI and the treatment effect was best when S/Fe was 0.1. The ARB (2 × 10(7) CFU/mL) could be completely inactivated by 1.12 g/L of S-nZVI (S/Fe = 0.1) within 15 min, and the removal rates of intracellular sul1 and intI1 reached up to 4.39 log and 4.67 log at 60 min, respectively. Quenching experiments and flow cytometry proved that reactive oxygen species and adsorption were involved in the ARB inactivation and target genes removal. Bacterial death and live staining experiments and transmission electron microscopy showed that the ARB cell structure and intracellular DNA were severely damaged after S-nZVI treatment. This study provided a potential alternative method for controlling the antibiotic resistance in aquatic environment.202032585519
779160.9979Investigation of reduction in risk from antibiotic resistance genes in laboratory wastewater by using O(3) , ultrasound, and autoclaving. Biological laboratory wastewater containing both antibiotic-resistant bacteria (ARB) and antibiotics is a potential source of antibiotic resistance genes (ARGs). Thus, we determined the efficacy of autoclaving, a common disinfection method, in eliminating 5 ARGs (sul1, sul2, tetW, tetM, amp) and the integrase-encoding gene intI1 from laboratory wastewater. Autoclaving (15 min, 121°C) inactivated all bacteria including ARB, whereas ARGs persisted in the wastewater with limited reduction even after 60 min of treatment. Ozonation (O(3) ), ultrasound (US), O(3) /US, and autoclaving followed by O(3) were investigated for their ability to reduce ARGs in laboratory wastewater. With O(3) and O(3) /US, the reduction rate ranged from 5.44 to 7.13 log for all ARGs investigated. Wastewater treatment with US alone did not reduce ARGs under the present experimental conditions (150 W, 53 kHz). Among the four treatments, autoclaving followed by O(3) treatment showed the highest reduction rates in the shortest time; however, further optimization and investigation are needed for the advanced treatment of bio-laboratory wastewater. Overall, this study provides novel insights into ARG sources and demonstrates that advanced oxidation methods can be useful to optimize laboratory wastewater treatment for ARG inactivation. PRACTITIONER POINTS: Bio-laboratory wastewater is potential reservoir of ARGs. Conventional autoclaving was not able to reduce ARGs to a low level. Autoclaving-O(3) completely eliminate all the bacteria. Autoclaving-O(3) reduced ARGs efficiently (6.12-7.86 logs removal in 60 min).202132891064
784270.9978Removal of Antibiotic Resistant Bacteria and Genes by UV-Assisted Electrochemical Oxidation on Degenerative TiO(2) Nanotube Arrays. Antibiotic resistance has become a global crisis in recent years, while wastewater treatment plants (WWTPs) have been identified as a significant source of both antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). However, commonly used disinfectants have been shown to be ineffective for the elimination of ARGs. With the goal of upgrading the conventional UV disinfection unit with stronger capability to combat ARB and ARGs, we developed a UV-assisted electrochemical oxidation (UV-EO) process that employs blue TiO(2) nanotube arrays (BNTAs) as photoanodes. Inactivation of tetracycline- and sulfamethoxazole-resistant E. coli along with degradation of the corresponding plasmid coded genes (tetA and sul1) is measured by plate counting on selective agar and qPCR, respectively. In comparison with UV(254) irradiation alone, enhanced ARB inactivation and ARG degradation is achieved by UV-EO. Chloride significantly promotes the inactivation efficiency due to the electrochemical production of free chlorine and the subsequent UV/chlorine photoreactions. The fluence-based first-order kinetic rate coefficients of UV-EO in Cl(-) are larger than those of UV(254) irradiation alone by a factor of 2.1-2.3 and 1.3-1.8 for the long and short target genes, respectively. The mechanism of plasmid DNA damage by different radical species is further explored using gel electrophoresis and computational kinetic modeling. The process can effectively eliminate ARB and ARGs in latrine wastewater, though the kinetics were retarded.202139605952
784780.9978Inactivation and change of tetracycline-resistant Escherichia coli in secondary effluent by visible light-driven photocatalytic process using Ag/AgBr/g-C(3)N(4). Control of antibiotic-resistant bacteria (ARB) and their related genes in secondary effluents has become a serious issue because of increased awareness of their health risks. A considerable number of techniques have been developed in recent years, particularly in relation to advanced oxidation. However, limited information is known about cellular behavior and resistance characteristic change during photocatalytic treatment. In this study, the inactivation of tetracycline (TC)-resistant Escherichia coli (TC-E. coli), removal of TC-resistant genes (TC-RGs), and antibiotic susceptibility were evaluated by employing photocatalytic treatment using Ag/AgBr/g-C(3)N(4) with visible light irradiation. The effects of light intensity, photocatalyst dosage, and reaction ambient temperature on photocatalysis were modelled and investigated. The rate of TC-E. coli removal was also optimized. Results demonstrated that the optimal conditions for TC-E. coli removal included light intensity of 96.0 mW/cm(2), photocatalyst dosage of 211.0 mg/L, and reaction ambient temperature of 23.7 °C. Under such conditions, the ARB removal rate was 6.1 log after 90 min and the related TC-RG removal rates were 49%, 86%, 69%, and 86% for tetA, tetM, tetQ, and intl1, respectively. The minimum inhibitory concentration test after photocatalysis shows that the antibiotic resistance of TC-E. coli was enhanced, which may be mainly due to the changes in the membrane potential and resulted in difficulty in destroying the bacteria through antibiotic contact. Hence, photocatalytic treatment could be an ideal method for ARB and antibiotic-resistant gene (ARG) control in wastewater, but the health risks of the remaining ARB and ARG should be investigated further.202031841919
782590.9978Comparison of different disinfection processes in the effective removal of antibiotic-resistant bacteria and genes. This study compared three different disinfection processes (chlorination, E-beam, and ozone) and the efficacy of three oxidants (H2O2, S2O(-)8, and peroxymonosulfate (MPS)) in removing antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in a synthetic wastewater. More than 30 mg/L of chlorine was needed to remove over 90% of ARB and ARG. For the E-beam method, only 1 dose (kGy) was needed to remove ARB and ARG, and ozone could reduce ARB and ARG by more than 90% even at 3 mg/L ozone concentration. In the ozone process, CT values (concentration × time) were compared for ozone alone and combined with different catalysts based on the 2-log removal of ARB and ARG. Ozone treatment yielded a value of 31 and 33 (mg·min)/L for ARB and ARGs respectively. On the other hand, ozone with persulfate yielded 15.9 and 18.5 (mg·min)/L while ozone with monopersulfate yielded a value of 12 and 14.5 (mg·min)/L. This implies that the addition of these catalysts significantly reduces the contact time to achieve a 2-log removal, thus enhancing the process in terms of its kinetics.201425079831
7835100.9978Crouching bacteria, hidden tetA genes in natural waters: Intracellular damage via double persulfate activation (UVA/Fe(2+)/PDS) effectively alleviates the spread of antibiotic resistance. In this study, we elucidated the chemical and biological inactivation mechanisms of peroxydisulfate (PDS) activated by UVA and Fe(2+) (UVA/Fe(2+)/PDS) in wild-type antibiotic-resistant bacteria (ARB) isolated from a river in Inner Mongolia. Among the screened wild-type ARB, the relative abundance of unidentified Enterobacteriaceae, Stenotrophomonas, and Ralstonia was high. A ratio of 1:1 for Fe(2+) and PDS under 18 W·m(-2) UVA radiation (sunny days) completely inactivated the environmental ARB isolates. In the macro view of the inactivation process, Fe(2+) first activates PDS rapidly, and later the UVA energy accumulated starts to activate PDS; HO• then becomes the main active species at a rate-limiting step. From a micro perspective, damage to the cell wall, intracellular proteins, inactivation of antioxidant enzymes, and genetic material degradation are the inactivation series of events by UVA/Fe(2+)/PDS, contributing to the 97.8 % inactivation of ARB at the initial stage. No regrowth of sublethal ARBs was observed. The transfer of tetracycline resistance genes from ARB to lab E. coli was evaluated by horizontal gene transfer (HGT), in which no HGT occurred when ARB was eliminated by UVA/Fe(2+)/PDS. Moreover, the sulfate and iron residuals in the effluents of treated water were lower than the drinking water standards. In summary, PDS, UVA, and Fe(2+) activation effectively inactivated wild ARB with a low concentration of reagents, while inhibiting their regrowth and spread of resistance due to the contribution of intracellular inactivation pathways.202439316921
7846110.9978Removal of antibiotic resistance genes and inactivation of antibiotic-resistant bacteria by oxidative treatments. The persistence of antibiotics in the environment because of human activities, such as seafood cultivation, has attracted great attention as they can give rise to antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB). In this study, we explored the inactivation and removal efficiencies of Escherichia coli SR1 and sul1 (plasmid-encoded ARGs), respectively, in their extracellular and intracellular forms (eARGs and iARGs) by three commonly used fishery oxidants, namely chlorine, bromine, and potassium permanganate (KMnO(4)), at the practical effective concentration range (0.5, 5, and 15 mg/L). Kinetics data were obtained using laboratory phosphate-buffered saline (PBS). Following the same fishery oxidation methods, the determined kinetics models were tested by studying the SR1 and sul1 disinfection efficiencies in (sterilized) pond water matrix. At concentrations of 5 and 15 mg/L, all three oxidants achieved sufficient cumulative integrated exposure (CT values) to completely inactivate SR1 and efficiently remove sul1 (up to 4.0-log). The oxidation methods were then applied to an unsterilized pond water matrix in order to study and evaluate the indigenous ARB and ARGs disinfection efficiencies in aquaculture, which reached 1.4-log and 1.0-log during treatment with fishery oxidants used in pond preparation at high concentrations before stocking (5-15 mg/L), respectively. A high chlorine concentration (15 mg/L) could efficiently remove ARGs (or iARGs) from pond water, and the iARG removal efficiency was higher than that of eARGs in pond water. The method and results of this study could aid in guiding future research and practical disinfection to control the spread of ARGs and ARB in aquaculture.202134030387
7802120.9978Inactivating facultative pathogen bacteria and antibiotic resistance genes in wastewater using blue light irradiation combined with a photosensitizer and hydrogen peroxide. The effectiveness of antimicrobial blue light (aBL) irradiation in eliminating ten clinically significant antibiotic resistance genes (ARGs) and four taxonomic marker genes of the WHO-priority ESKAPE bacteria group from wastewater treatment plant (WWTP) effluent was examined. Experiments were conducted using an LED-driven continuous-flow photoreactor operating at wavelengths of 405 nm, 420 nm, and 460 nm. Irradiation with aBL alone was insufficient for effectively inactivating or eliminating ESKAPE bacteria and clinically relevant ARGs. The addition of the porphyrin-based photosensitizer TMPyP (10(-6) M) or the oxidative agent H₂O₂ (1 mM) resulted in several log(10) unit reductions of facultative pathogenic bacteria (FPB), their taxonomic gene markers, and target ARGs. However, the additional effects of TMPyP and H(2)O(2) were only noticeable in conjunction with aBL irradiation, as they were ineffective without it. The reduction of the different FPB and ARGs in WWTP effluents was analyzed using culturing and qPCR together with living/dead discrimination. Different FPB and ARGs showed varying susceptibility to aBL-mediated irradiation. Among the FPB, enterococci were the most sensitive, while among the ARGs bacteria carrying ermB, tetM, sul1, and bla(VIM) genes exhibited the strongest removal. This sensitivity may be due to the gene-carrying microorganism's response to aBL irradiation combined with TMPyP or H(2)O(2). Additionally, molecular biology results revealed that aBL irradiation induced up to 13 lesions per 10 kb DNA, which is hypothesized to contribute to the acute inactivation effect and prevent regrowth by inhibiting DNA repair activities.202540138903
7792130.9978Comparative 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
7794140.9978Fate 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
7824150.9978H(2)O(2) and/or TiO(2) photocatalysis under UV irradiation for the removal of antibiotic resistant bacteria and their antibiotic resistance genes. Inactivating antibiotic resistant bacteria (ARB) and removing antibiotic resistance genes (ARGs) are very important to prevent their spread into the environment. Previous efforts have been taken to eliminate ARB and ARGs from aqueous solution and sludges, however, few satisfying results have been obtained. This study investigated whether photocatalysis by TiO(2) was able to reduce the two ARGs, mecA and ampC, within the host ARB, methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, respectively. The addition of H(2)O(2) and matrix effect on the removal of ARB and ARGs were also studied. TiO(2) thin films showed great effect on both ARB inactivation and ARGs removal. Approximately 4.5-5.0 and 5.5-5.8 log ARB reductions were achieved by TiO(2) under 6 and 12mJ/cm(2) UV(254) fluence dose, respectively. For ARGs, 5.8 log mecA reduction and 4.7 log ampC reduction were achieved under 120mJ/cm(2) UV(254) fluence dose in the presence of TiO(2). Increasing dosage of H(2)O(2) enhanced the removal efficiencies of ARB and ARGs. The results also demonstrated that photocatalysis by TiO(2) was capable of removing both intracellular and extracellular forms of ARGs. This study provided a potential alternative method for the removal of ARB and ARGs from aqueous solution.201727776873
7793160.9978Treatment 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
7204170.9978Solar-light driven photodegradation of antimicrobials, their transformation by-products and antibiotic resistance determinants in treated wastewater. This study aimed to assess the possibility of using solar light-driven photolysis and TiO(2)-based photocatalysis to remove (1) antibiotic residues, (2) their transformation products (TPs), (3) antibiotic resistance determinants, and (4) genes identifying the indicator bacteria in a treated wastewater (secondary effluent). 16 antimicrobials belonging to the different classes and 45 their transformation by-products were selected for the study. The most susceptible to photochemical decomposition was tetracycline, which was completely removed in the photocatalysis process and in more than 80% in the solar light-driven photolysis. 83.8% removal (on average) was observed using photolysis and 89.9% using photocatalysis in the case of the tested genes, among which the genes sul1, uidA, and intI1 showed the highest degree of removal by both methods. The study revealed that applied methods promisingly remove the tested antibiotics, their TPs and genes even in such a complex matrix including treated wastewater and photocatalysis process had a higher removal efficiency of antibiotics, TPs and genes tested. Moreover, the high percentage removal of the intI1 gene (>93%) indicates the possibilities of use of the solar light-driven photolysis and TiO(2)-based photocatalysis in minimizing the antibiotic resistance genes transfer by mobile genetic elements.202235469868
7788180.9977Inactivation of antibiotic resistant Escherichia coli and degradation of its resistance genes by glow discharge plasma in an aqueous solution. Emerging contaminants such as antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs) are becoming a global environmental problem. In this study, the glow discharge plasma (GDP) was applied for degrading antibiotic resistant Escherichia coli (E. coli) with resistance genes (tetA, tetR, aphA) and transposase gene (tnpA) in 0.9% sterile saline. The results showed that GDP was able to inactivate the antibiotic resistant E. coli and remove the ARGs and reduce the risk of gene transfer. The levels of E. coli determined by 16S rRNA decreased by approximately 4.7 logs with 15 min of discharge treatment. Propidium monoazide - quantitative polymerase chain reaction (PMA-qPCR) tests demonstrated that the cellular structure of 4.8 more logs E. coli was destroyed in 15 min. The reduction of tetA, tetR, aphA, tnpA genes was increased to 5.8, 5.4, 5.3 and 5.5 logs with 30 min discharge treatment, respectively. The removal of ARGs from high salinity wastewater was also investigated. The total abundance of ARGs was reduced by 3.9 logs in 30 min. Scavenging tests indicated that hydroxyl radicals (·OH) was the most probable agents for bacteria inactivation and ARGs degradation. In addition, the active chlorine (Cl· and Cl(2)) which formed during the discharge may also contribute to the inactivation and degradation.202032229364
7763190.9977Antibiotic resistance genes fate and removal by a technological treatment solution for water reuse in agriculture. In order to mitigate the potential effects on the human health which are associated to the use of treated wastewater in agriculture, antibiotic resistance genes (ARGs) are required to be carefully monitored in wastewater reuse processes and their spread should be prevented by the development of efficient treatment technologies. Objective of this study was the assessment of ARGs reduction efficiencies of a novel technological treatment solution for agricultural reuse of municipal wastewaters. The proposed solution comprises an advanced biological treatment (Sequencing Batch Biofilter Granular Reactor, SBBGR), analysed both al laboratory and pilot scale, followed by sand filtration and two different disinfection final stages: ultraviolet light (UV) radiation and peracetic acid (PAA) treatments. By Polymerase Chain Reaction (PCR), the presence of 9 ARGs (ampC, mecA, ermB, sul1, sul2, tetA, tetO, tetW, vanA) were analysed and by quantitative PCR (qPCR) their removal was determined. The obtained results were compared to the reduction of total bacteria (16S rDNA gene) and of a faecal contamination indicator (Escherichia coli uidA gene). Only four of the analysed genes (ermB, sul1, sul2, tetA) were detected in raw wastewater and their abundance was estimated to be 3.4±0.7 x10(4) - 9.6±0.5 x10(9) and 1.0±0.3 x10(3) to 3.0±0.1 x10(7) gene copies/mL in raw and treated wastewaters, respectively. The results show that SBBGR technology is promising for the reduction of ARGs, achieving stable removal performance ranging from 1.0±0.4 to 2.8±0.7 log units, which is comparable to or higher than that reported for conventional activated sludge treatments. No reduction of the ARGs amount normalized to the total bacteria content (16S rDNA), was instead obtained, indicating that these genes are removed together with total bacteria and not specifically eliminated. Enhanced ARGs removal was obtained by sand filtration, while no reduction was achieved by both UV and PAA disinfection treatments tested in our study.201627450254