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Ofori I, Maddila S, Lin J, Jonnalagadda SB. Chlorine dioxide oxidation of Escherichia coli in water - A study of the disinfection kinetics and mechanism. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2017; 52:598-606. [PMID: 28301286 DOI: 10.1080/10934529.2017.1293993] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This study investigated the kinetics and mechanism of chlorine dioxide (ClO2) inactivation of a Gram-negative bacteria Escherichia coli (ATCC 35218) in oxidant demand free (ODF) water in detail as a function of disinfectant concentration (0.5-5.0 mg/L), water pH (6.5-8.5), temperature variations (4-37°C) and bacterial density (105-107 cfu/mL). The effects of ClO2 on bacterial cell morphology, outer membrane permeability, cytoplasmic membrane disruption and intracellular enzymatic activity were also studied to elucidate the mechanism of action on the cells. Increasing temperature and disinfectant concentration were proportional to the rate of cell killing, but efficacy was found to be significantly subdued at 0.5 mg/L and less dependent on the bacterial density. The bactericidal efficiency was higher at alkaline pH of 8 or above as compared to neutral and slightly acidic pH of 7 and 6.5 respectively. The disinfection kinetic curves followed a biphasic pattern of rapid inactivation within the initial 2 min which were followed by a tailing even in the presence of residual biocide. The curves were adequately described by the Cavg Hom model. Transmission Electron Microscopy images of the bacteria cells exposed to lethal concentrations of ClO2 indicated very little observable morphological damage to the outer membranes of the cells. ClO2 however was found to increase the permeability of the outer and cytoplasmic membranes leading to the leakage of membrane components such as 260 nm absorbing materials and inhibiting the activity of the intracellular enzyme β-D-galactosidase. It is suggested that the disruption of the cytoplasmic membrane and subsequent efflux of intracellular components result in the inactivation of the Gram-negative bacteria.
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Affiliation(s)
- Isaac Ofori
- a School of Chemistry & Physics, University of KwaZulu-Natal , Westville Campus, Chiltern Hills, Durban , South Africa
| | - Suresh Maddila
- a School of Chemistry & Physics, University of KwaZulu-Natal , Westville Campus, Chiltern Hills, Durban , South Africa
| | - Johnson Lin
- b School of Life Sciences, Discipline of Microbiology, University of KwaZulu-Natal , Chiltern Hills, Durban , South Africa
| | - Sreekantha B Jonnalagadda
- a School of Chemistry & Physics, University of KwaZulu-Natal , Westville Campus, Chiltern Hills, Durban , South Africa
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202
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The Occurrence of the Colistin Resistance Gene mcr-1 in the Haihe River (China). INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2017; 14:ijerph14060576. [PMID: 28555063 PMCID: PMC5486262 DOI: 10.3390/ijerph14060576] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 05/23/2017] [Accepted: 05/25/2017] [Indexed: 12/14/2022]
Abstract
Antibiotic failure is occurring worldwide. In a routine surveillance study on antibiotic resistance genes (ARGs) in natural water bodies, we noted the detection of colistin-resistance gene mcr-1, previously identified in Escherichia coli and Klebsiella pneumoniae isolates from human beings and animals in several countries. The mcr-1 gene might be present in water environments, because aquatic ecosystems are recognized as reservoirs for antibiotic resistant bacteria (ARB) and ARGs. In this study, a qPCR assay was developed to monitor and quantify the mcr-1 gene in the Haihe River, China. The results showed that all 18 samples collected from different locations over 6 months along the Haihe River were positive for the mcr-1 gene, and the highest level of mcr-1 reached 3.81 × 105 gene copies (GC) per liter of water. This is the first study to quantify mcr-1 in a natural water system by qPCR. Our findings highlight the potential for this antibiotic resistance determinant to spread extensively, suggesting a significant health and ecological impact.
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203
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Fang H, Zhang Q, Nie X, Chen B, Xiao Y, Zhou Q, Liao W, Liang X. Occurrence and elimination of antibiotic resistance genes in a long-term operation integrated surface flow constructed wetland. CHEMOSPHERE 2017; 173:99-106. [PMID: 28107719 DOI: 10.1016/j.chemosphere.2017.01.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 12/05/2016] [Accepted: 01/04/2017] [Indexed: 06/06/2023]
Abstract
Wetland construction is a recommended domestic sewage treatment technique, owing to its simplicity and cost efficiency. Concentrations of 14 antibiotic resistance genes (ARGs) in an integrated surface flow constructed wetland (ICW) steadily operated over 10 years were investigated in the winter and summer. Domestic sewage was observed to be the primary source of ARGs in the ICW, and 77.8% and 59.5% removal rates of total targeted ARGs in the ICW were achieved in the winter and summer, respectively. Concentrations of five ARGs (sul1, tetA, tetC, tetE, and qnrS) in the winter and of six ARGs (sul1, sul3, tetA, tetC, tetE, and qnrS) in the summer were increased throughout the treatment process. Strong correlations were found between ARGs in water and those found in sediments, especially in the summer, indicating that ARGs may be exchanged between water and sediment. Strong positive correlations were also observed between concentrations of intI1 and several ARGs, implying that mobile genetic elements may play a key role in the dissemination of ARGs in an ICW. Our study results suggest aqueous ARGs could be effectively removed via an ICW and that ICWs can also act as reservoirs of specific ARGs.
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Affiliation(s)
- Hansun Fang
- Key Laboratory of Poyang Lake Basin Agricultural Resource and Ecology of Jiangxi Province, College of Land Resource and Environment, Jiangxi Agricultural University, Nanchang 330045, China
| | - Qin Zhang
- Key Laboratory of Poyang Lake Basin Agricultural Resource and Ecology of Jiangxi Province, College of Land Resource and Environment, Jiangxi Agricultural University, Nanchang 330045, China
| | - Xiangping Nie
- Department of Ecology, Jinan University, Guangzhou 510632, China
| | - Baowei Chen
- MOE Key Laboratory of Aquatic Product Safety, School of Marine Sciences, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Yuandong Xiao
- Key Laboratory of Poyang Lake Basin Agricultural Resource and Ecology of Jiangxi Province, College of Land Resource and Environment, Jiangxi Agricultural University, Nanchang 330045, China
| | - Qiubai Zhou
- College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang 330045, China
| | - Wei Liao
- Irrigation Experiment Station of Jiangxi, Nanchang 338026, China
| | - Ximei Liang
- College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang 330045, China.
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204
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Ben W, Wang J, Cao R, Yang M, Zhang Y, Qiang Z. Distribution of antibiotic resistance in the effluents of ten municipal wastewater treatment plants in China and the effect of treatment processes. CHEMOSPHERE 2017; 172:392-398. [PMID: 28088530 DOI: 10.1016/j.chemosphere.2017.01.041] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 01/01/2017] [Accepted: 01/05/2017] [Indexed: 05/23/2023]
Abstract
Municipal wastewater treatment plant (WWTP) effluents represent an important contamination source of antibiotic resistance, threatening the ecological safety of receiving environments. In this study, the release of antibiotic resistance to sulfonamides and tetracyclines in the effluents of ten WWTPs in China was investigated. Results indicate that the concentrations of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) ranged from 1.1 × 101 to 8.9 × 103 CFU mL-1 and 3.6 × 101 (tetW) to 5.4 × 106 (tetX) copies mL-1, respectively. There were insignificant correlations of the concentrations of ARB and ARGs with those of corresponding antibiotics. Strong correlations were observed between the total concentrations of tetracycline resistance genes and sulfonamide resistance genes, and both of which were significantly correlated with intI1 concentrations. Statistical analysis of the effluent ARG concentrations in different WWTPs revealed an important role of disinfection in eliminating antibiotic resistance. The release rates of ARB and ARGs through the effluents of ten WWTPs ranged from 5.9 × 1012 to 4.8 × 1015 CFU d-1 and 6.4 × 1012 (tetW) to 1.7 × 1018 (sul1) copies d-1, respectively. This study helps the effective assessment and scientific management of ecological risks induced by antibiotic resistance discharged from WWTPs.
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Affiliation(s)
- Weiwei Ben
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China
| | - Jian Wang
- Institute of Energy and Environmental Protection, Chinese Academy of Agricultural Engineering, 41 Maizidian Street, Beijing 100125, China; Key Laboratory of Energy Resource Utilization from Agricultural Residues, Ministry of Agriculture, 41 Maizidian Street, Beijing 100125, China
| | - Rukun Cao
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China
| | - Min Yang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China
| | - Yu Zhang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China
| | - Zhimin Qiang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China.
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205
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Zhang Y, Gu AZ, He M, Li D, Chen J. Subinhibitory Concentrations of Disinfectants Promote the Horizontal Transfer of Multidrug Resistance Genes within and across Genera. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:570-580. [PMID: 27997135 DOI: 10.1021/acs.est.6b03132] [Citation(s) in RCA: 259] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The greater abundances of antibiotic resistance genes (ARGs) in point-of-use tap and reclaimed water than that in freshly treated water raise the question whether residual disinfectants in distribution systems facilitate the spread of ARGs. This study investigated three widely used disinfectants (free chlorine, chloramine, and hydrogen peroxide) on promoting ARGs transfer within Escherichia coli strains and across genera from Escherichia coli to Salmonella typhimurium. The results demonstrated that subinhibitory concentrations (lower than minimum inhibitory concentrations [MICs]) of these disinfectants, namely 0.1-1 mg/L Cl2 for free chlorine, 0.1-1 mg/L Cl2 for chloramine, and 0.24-3 mg/L H2O2, led to concentration-dependent increases in intragenera conjugative transfer by 3.4-6.4, 1.9-7.5, and 1.4-5.4 folds compared with controls, respectively. By comparison, the intergenera conjugative frequencies were slightly increased by approximately 1.4-2.3 folds compared with controls. However, exposure to disinfectants concentrations higher than MICs significantly suppressed conjugative transfer. This study provided evidence and insights into possible underlying mechanisms for enhanced conjugative transfer, which involved intracellular reactive oxygen species formation, SOS response, increased cell membrane permeability, and altered expressions of conjugation-relevant genes. The results suggest that certain oxidative chemicals, such as disinfectants, accelerate ARGs transfer and therefore justify motivations in evaluating disinfection alternatives for controlling antibiotic resistance. This study also triggers questions regarding the potential role of environmental chemicals in the global spread of antibiotic resistance.
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Affiliation(s)
- Ye Zhang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University , Shanghai 200433, China
| | - April Z Gu
- Department of Civil and Environmental Engineering, Northeastern University , Boston, Massachusetts 02115, United States
| | - Miao He
- Environmental Simulation and Pollution Control (ESPC) State Key Joint Laboratory, School of Environment, Tsinghua University , Beijing 100084, China
| | - Dan Li
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University , Shanghai 200433, China
| | - Jianmin Chen
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University , Shanghai 200433, China
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206
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Di Cesare A, Fontaneto D, Doppelbauer J, Corno G. Fitness and Recovery of Bacterial Communities and Antibiotic Resistance Genes in Urban Wastewaters Exposed to Classical Disinfection Treatments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:10153-61. [PMID: 27548377 DOI: 10.1021/acs.est.6b02268] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Antibiotic resistance genes (ARGs) are increasingly appreciated to be important as micropollutants. Indirectly produced by human activities, they are released into the environment, as they are untargeted by conventional wastewater treatments. In order to understand the fate of ARGs and of other resistant forms (e.g., phenotypical adaptations) in urban wastewater treatment plants (WWTPs), we monitored three WWTPs with different disinfection processes (chlorine, peracetic acid (PAA), and ultraviolet light (UV)). We monitored WWTPs influx and pre- and postdisinfection effluent over 24 h, followed by incubation experiments lasting for 96 h. We measured bacterial abundance, size distribution and aggregational behavior, the proportion of intact (active) cells, and the abundances of four ARGs and of the mobile element integron1. While all the predisinfection treatments of all WWTPs removed the majority of bacteria and of associated ARGs, of the disinfection processes only PAA efficiently removed bacterial cells. However, the stress imposed by PAA selected for bacterial aggregates and, similarly to chlorine, stimulated the selection of ARGs during the incubation experiment. This suggests disinfections based on chemically aggressive destruction of bacterial cell structures can promote a residual microbial community that is more resistant to antibiotics and, given the altered aggregational behavior, to competitive stress in nature.
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Affiliation(s)
- Andrea Di Cesare
- Microbial Ecology Group, National Research Council of Italy, Institute of Ecosystem Study - Largo Tonolli 50, 28922 Verbania, Italy
| | - Diego Fontaneto
- Microbial Ecology Group, National Research Council of Italy, Institute of Ecosystem Study - Largo Tonolli 50, 28922 Verbania, Italy
| | - Julia Doppelbauer
- Microbial Ecology Group, National Research Council of Italy, Institute of Ecosystem Study - Largo Tonolli 50, 28922 Verbania, Italy
| | - Gianluca Corno
- Microbial Ecology Group, National Research Council of Italy, Institute of Ecosystem Study - Largo Tonolli 50, 28922 Verbania, Italy
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207
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Sharma VK, Johnson N, Cizmas L, McDonald TJ, Kim H. A review of the influence of treatment strategies on antibiotic resistant bacteria and antibiotic resistance genes. CHEMOSPHERE 2016; 150:702-714. [PMID: 26775188 DOI: 10.1016/j.chemosphere.2015.12.084] [Citation(s) in RCA: 380] [Impact Index Per Article: 47.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Revised: 12/08/2015] [Accepted: 12/22/2015] [Indexed: 05/20/2023]
Abstract
Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG) in the aquatic environment have become an emerging contaminant issue, which has implications for human and ecological health. This review begins with an introduction to the occurrence of ARB and ARG in different environmental systems such as natural environments and drinking water resources. For example, ARG or ARB with resistance to ciprofloxacin, sulfamethoxazole, trimethoprim, quinolone, vancomycin, or tetracycline (e.g., tet(A), tet(B), tet(C), tet(G), tet(O), tet(M), tet(W), sul I, and sul II) have been detected in the environment. The development of resistance may be intrinsic, may be acquired through spontaneous mutations (de novo), or may occur due to horizontal gene transfer from donor bacteria, phages, or free DNA to recipient bacteria. An overview is also provided of the current knowledge regarding inactivation of ARB and ARG, and the mechanism of the effects of different disinfection processes in water and wastewater (chlorination, UV irradiation, Fenton reaction, ozonation, and photocatalytic oxidation). The effects of constructed wetlands and nanotechnology on ARB and ARG are also summarized.
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Affiliation(s)
- Virender K Sharma
- Department of Environmental and Occupational Health, School of Public Health, Texas A&M University, College Station, TX 77843, USA.
| | - Natalie Johnson
- Department of Environmental and Occupational Health, School of Public Health, Texas A&M University, College Station, TX 77843, USA
| | - Leslie Cizmas
- Department of Environmental and Occupational Health, School of Public Health, Texas A&M University, College Station, TX 77843, USA
| | - Thomas J McDonald
- Department of Environmental and Occupational Health, School of Public Health, Texas A&M University, College Station, TX 77843, USA
| | - Hyunook Kim
- Department of Energy & Environmental System Engineering, The University of Seoul, 90 Jeonnong-dong Dongdaemun-gu, Seoul 130-743, Republic of Korea
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208
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Zhang Y, Zhuang Y, Geng J, Ren H, Xu K, Ding L. Reduction of antibiotic resistance genes in municipal wastewater effluent by advanced oxidation processes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 550:184-191. [PMID: 26815295 DOI: 10.1016/j.scitotenv.2016.01.078] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Revised: 01/12/2016] [Accepted: 01/14/2016] [Indexed: 05/22/2023]
Abstract
This study investigated the reduction of antibiotic resistance genes (ARGs), intI1 and 16S rRNA genes, by advanced oxidation processes (AOPs), namely Fenton oxidation (Fe(2+)/H2O2) and UV/H2O2 process. The ARGs include sul1, tetX, and tetG from municipal wastewater effluent. The results indicated that the Fenton oxidation and UV/H2O2 process could reduce selected ARGs effectively. Oxidation by the Fenton process was slightly better than that of the UV/H2O2 method. Particularly, for the Fenton oxidation, under the optimal condition wherein Fe(2+)/H2O2 had a molar ratio of 0.1 and a H2O2 concentration of 0.01molL(-1) with a pH of 3.0 and reaction time of 2h, 2.58-3.79 logs of target genes were removed. Under the initial effluent pH condition (pH=7.0), the removal was 2.26-3.35 logs. For the UV/H2O2 process, when the pH was 3.5 with a H2O2 concentration of 0.01molL(-1) accompanied by 30min of UV irradiation, all ARGs could achieve a reduction of 2.8-3.5 logs, and 1.55-2.32 logs at a pH of 7.0. The Fenton oxidation and UV/H2O2 process followed the first-order reaction kinetic model. The removal of target genes was affected by many parameters, including initial Fe(2+)/H2O2 molar ratios, H2O2 concentration, solution pH, and reaction time. Among these factors, reagent concentrations and pH values are the most important factors during AOPs.
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Affiliation(s)
- Yingying Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, People's Republic of China
| | - Yao Zhuang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, People's Republic of China
| | - Jinju Geng
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, People's Republic of China.
| | - Hongqiang Ren
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, People's Republic of China
| | - Ke Xu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, People's Republic of China
| | - Lili Ding
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, People's Republic of China
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209
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Ding C, Pan J, Jin M, Yang D, Shen Z, Wang J, Zhang B, Liu W, Fu J, Guo X, Wang D, Chen Z, Yin J, Qiu Z, Li J. Enhanced uptake of antibiotic resistance genes in the presence of nanoalumina. Nanotoxicology 2016; 10:1051-60. [DOI: 10.3109/17435390.2016.1161856] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Chengshi Ding
- College of Life Science, Shandong Normal University, Jinan, China
- College of Life Science, Zaozhuang University, Zaozhuang, China
| | - Jie Pan
- College of Life Science, Shandong Normal University, Jinan, China
| | - Min Jin
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Dong Yang
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Zhiqiang Shen
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Jingfeng Wang
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Bin Zhang
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Weili Liu
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Jialun Fu
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Xuan Guo
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Daning Wang
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Zhaoli Chen
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Jing Yin
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Zhigang Qiu
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Junwen Li
- Tianjin Institute of Health and Environmental Medicine, Tianjin, China
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210
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Lin W, Li S, Zhang S, Yu X. Reduction in horizontal transfer of conjugative plasmid by UV irradiation and low-level chlorination. WATER RESEARCH 2016; 91:331-338. [PMID: 26803268 DOI: 10.1016/j.watres.2016.01.020] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 12/29/2015] [Accepted: 01/11/2016] [Indexed: 06/05/2023]
Abstract
The widespread presence of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) in the drinking water system facilitates their horizontal gene transfer among microbiota. In this study, the conjugative gene transfer of RP4 plasmid after disinfection including ultraviolet (UV) irradiation and low-level chlorine treatment was investigated. It was found that both UV irradiation and low-level chlorine treatment reduced the conjugative gene transfer frequency. The transfer frequency gradually decreased from 2.75 × 10(-3) to 2.44 × 10(-5) after exposure to UV doses ranging from 5 to 20 mJ/cm(2). With higher UV dose of 50 and 100 mJ/cm(2), the transfer frequency was reduced to 1.77 × 10(-6) and 2.44 × 10(-8). The RP4 plasmid transfer frequency was not significantly affected by chlorine treatment at dosages ranging from 0.05 to 0.2 mg/l, but treatment with 0.3-0.5 mg/l chlorine induced a decrease in conjugative transfer to 4.40 × 10(-5) or below the detection limit. The mechanisms underlying these phenomena were also explored, and the results demonstrated that UV irradiation and chlorine treatment (0.3 and 0.5 mg/l) significantly reduced the viability of bacteria, thereby lowering the conjugative transfer frequency. Although the lower chlorine concentrations tested (0.05-0.2 mg/l) were not sufficient to damage the cells, exposure to these concentrations may still depress the expression of a flagellar gene (FlgC), an outer membrane porin gene (ompF), and a DNA transport-related gene (TraG). Additionally, fewer pili were scattered on the bacteria after chlorine treatment. These findings are important in assessing and controlling the risk of ARG transfer and dissemination in the drinking water system.
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Affiliation(s)
- Wenfang Lin
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Shuai Li
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Shuting Zhang
- College of Environment and Safety Engineering, Shenyang University of Chemical Technology, Shenyang, 110142, China
| | - Xin Yu
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
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211
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Co-Selection of Resistance to Antibiotics, Biocides and Heavy Metals, and Its Relevance to Foodborne Pathogens. Antibiotics (Basel) 2015; 4:567-604. [PMID: 27025641 PMCID: PMC4790313 DOI: 10.3390/antibiotics4040567] [Citation(s) in RCA: 235] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 11/05/2015] [Accepted: 11/06/2015] [Indexed: 02/07/2023] Open
Abstract
Concerns have been raised in recent years regarding co-selection for antibiotic resistance among bacteria exposed to biocides used as disinfectants, antiseptics and preservatives, and to heavy metals (particularly copper and zinc) used as growth promoters and therapeutic agents for some livestock species. There is indeed experimental and observational evidence that exposure to these non-antibiotic antimicrobial agents can induce or select for bacterial adaptations that result in decreased susceptibility to one or more antibiotics. This may occur via cellular mechanisms that are protective across multiple classes of antimicrobial agents or by selection of genetic determinants for resistance to non-antibiotic agents that are linked to genes for antibiotic resistance. There may also be relevant effects of these antimicrobial agents on bacterial community structure and via non-specific mechanisms such as mobilization of genetic elements or mutagenesis. Notably, some co-selective adaptations have adverse effects on fitness in the absence of a continued selective pressure. The present review examines the evidence for the significance of these phenomena, particularly in respect of bacterial zoonotic agents that commonly occur in livestock and that may be transmitted, directly or via the food chain, to human populations.
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212
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Jia S, Shi P, Hu Q, Li B, Zhang T, Zhang XX. Bacterial Community Shift Drives Antibiotic Resistance Promotion during Drinking Water Chlorination. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:12271-9. [PMID: 26397118 DOI: 10.1021/acs.est.5b03521] [Citation(s) in RCA: 286] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
For comprehensive insights into the effects of chlorination, a widely used disinfection technology, on bacterial community and antibiotic resistome in drinking water, this study applied high-throughput sequencing and metagenomic approaches to investigate the changing patterns of antibiotic resistance genes (ARGs) and bacterial community in a drinking water treatment and distribution system. At genus level, chlorination could effectively remove Methylophilus, Methylotenera, Limnobacter, and Polynucleobacter, while increase the relative abundance of Pseudomonas, Acidovorax, Sphingomonas, Pleomonas, and Undibacterium in the drinking water. A total of 151 ARGs within 15 types were detectable in the drinking water, and chlorination evidently increased their total relative abundance while reduced their diversity in the opportunistic bacteria (p < 0.05). Residual chlorine was identified as the key contributing factor driving the bacterial community shift and resistome alteration. As the dominant persistent ARGs in the treatment and distribution system, multidrug resistance genes (mainly encoding resistance-nodulation-cell division transportation system) and bacitracin resistance gene bacA were mainly carried by chlorine-resistant bacteria Pseudomonas and Acidovorax, which mainly contributed to the ARGs abundance increase. The strong correlation between bacterial community shift and antibiotic resistome alteration observed in this study may shed new light on the mechanism behind the chlorination effects on antibiotic resistance.
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Affiliation(s)
- Shuyu Jia
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University , Nanjing 210023, China
| | - Peng Shi
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University , Nanjing 210023, China
| | - Qing Hu
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University , Nanjing 210023, China
| | - Bing Li
- Environmental Biotechnology Lab, Department of Civil Engineering, The University of Hong Kong , Hong Kong SAR, China
| | - Tong Zhang
- Environmental Biotechnology Lab, Department of Civil Engineering, The University of Hong Kong , Hong Kong SAR, China
| | - Xu-Xiang Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University , Nanjing 210023, China
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