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Obe T, Kiess AS, Nannapaneni R. Antimicrobial Tolerance in Salmonella: Contributions to Survival and Persistence in Processing Environments. Animals (Basel) 2024; 14:578. [PMID: 38396546 PMCID: PMC10886206 DOI: 10.3390/ani14040578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 02/01/2024] [Accepted: 02/07/2024] [Indexed: 02/25/2024] Open
Abstract
Salmonella remains a top bacterial pathogen implicated in several food-borne outbreaks, despite the use of antimicrobials and sanitizers during production and processing. While these chemicals have been effective, Salmonella has shown the ability to survive and persist in poultry processing environments. This can be credited to its microbial ability to adapt and develop/acquire tolerance and/or resistance to different antimicrobial agents including oxidizers, acids (organic and inorganic), phenols, and surfactants. Moreover, there are several factors in processing environments that can limit the efficacy of these antimicrobials, thus allowing survival and persistence. This mini-review examines the antimicrobial activity of common disinfectants/sanitizers used in poultry processing environments and the ability of Salmonella to respond with innate or acquired tolerance and survive exposure to persists in such environments. Instead of relying on a single antimicrobial agent, the right combination of different disinfectants needs to be developed to target multiple pathways within Salmonella.
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Affiliation(s)
- Tomi Obe
- Department of Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA
| | - Aaron S. Kiess
- Prestage Department of Poultry Science, College of Agriculture and Life Sciences, North Carolina State University, Raleigh, NC 27695, USA;
| | - Ramakrishna Nannapaneni
- Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi, MS 39762, USA;
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2
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Jing K, Li Y, Yao C, Jiang C, Li J. Towards the fate of antibiotics and the development of related resistance genes in stream biofilms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 898:165554. [PMID: 37454845 DOI: 10.1016/j.scitotenv.2023.165554] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/01/2023] [Accepted: 07/13/2023] [Indexed: 07/18/2023]
Abstract
Antibiotics are ubiquitously found in natural surface waters and cause great harm to aquatic organisms. Stream biofilm is a complex and active community composed of algae, bacteria, fungi and other microorganisms, which mainly adheres to solid substances such as rocks and sediments. The durability and diverse structural and metabolic characteristics of biofilms make them a representative of microbial life in aquatic micrecosystems and can reflect major ecosystem processes. Microorganisms and extracellular polymeric substances in biofilms can adsorb and actively accumulate antibiotics. Therefore, biofilms are excellent biological indicators for detecting antibiotic in polluted aquatic environments, but the biotransformation potential of stream biofilms for antibiotics has not been fully explored in the aquatic environment. The characteristics of stream biofilm, such as high abundance and activity of bacterial community, wide contact area with pollutants, etc., which increases the opportunity of biotransformation of antibiotics in biofilm and contribute to bioremediation to improve ecosystem health. Recent studies have demonstrated that both exposure to high and sub-minimum inhibitory concentrations of antibiotics may drive the development of antibiotic resistance genes (ARGs) in natural stream biofilms, which are susceptible to the effects of antibiotic residues, microbial communities and mobile genetic elements, etc. On the basis of peer-reviewed papers, this review explores the distribution behavior of antibiotics in stream biofilms and the contribution of biofilms to the acquisition and spread of antibiotic resistance. Considering that antibiotics and ARGs alter the structure and ecological functions of natural microbial communities and pose a threat to river organisms and human health, our research findings provide comprehensive insights into the migration, transformation, and bioavailability of antibiotics in biofilms.
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Affiliation(s)
- Ke Jing
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, HoHai University, Nanjing 210098, China
| | - Ying Li
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, HoHai University, Nanjing 210098, China.
| | - Chi Yao
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, HoHai University, Nanjing 210098, China
| | - Chenxue Jiang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, HoHai University, Nanjing 210098, China
| | - Jing Li
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, HoHai University, Nanjing 210098, China
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3
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Xu X, Cao R, Li K, Wan Q, Wu G, Lin Y, Huang T, Wen G. The protective role and mechanism of melanin for Aspergillus niger and Aspergillus flavus against chlorine-based disinfectants. WATER RESEARCH 2022; 223:119039. [PMID: 36084430 DOI: 10.1016/j.watres.2022.119039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 08/20/2022] [Accepted: 08/29/2022] [Indexed: 06/15/2023]
Abstract
Melanin is a critical component of fungal cell wall which protect fungi from adverse environmental tress. However, the role of melanin for fungi during the disinfection with chlorine-based disinfectants has not been elucidated. The results showed that the inactivation rate constants of Aspergillus niger with chlorine and chlorine dioxide decreased from 0.08 to 2.10 min-1 to 0 after addition of 0.32 mg/L melanin. The results indicated addition of extracted fungal melanin inhibited the inactivation efficiency of chlorine and chlorine dioxide. In contrast, the k of Aspergillus niger after inactivation with monochloramine ranged from 1.50 to 1.78 min-1 after addition of melanin which indicated effect of melanin on the inactivation efficiency of monochloramine was negligible. In addition, the extracted fungal melanin exhibited high reactivity with chlorine and chlorine dioxide but very low reactivity with monochloramine. The different inactivation mechanisms of chlorine-based disinfectants and different reactivity of melanin with chlorine-based disinfectants led to the different protective mechanism of melanin for A. niger and A. flavus spores against disinfection with chlorine-based disinfectants. The chlorine and chlorine dioxide appeared to react with functional groups of melanin in cell wall of spores, so sacrificial reactions between melanin and disinfectants decreased the available disinfectants and limited the diffusion of disinfectants to the reactive site on cell membrane, which led to the decrease of the disinfection efficiency for chlorine and chlorine dioxide. The monochloramine could penetrate into cell and damage DNA without the effect of melanin due to its strong penetration and low reactivity with melanin. Our results systematically demonstrate the protective roles of melanin on the fungal spores against chlorine-based disinfectants and the underlying mechanisms in resisting the environmental stress caused by chlorine-based disinfectants, which provides important implications for the control of fungi, especially for fungi producing melanin.
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Affiliation(s)
- Xiangqian Xu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Ruihua Cao
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Kai Li
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Qiqi Wan
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Gehui Wu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Yuzhao Lin
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Tinglin Huang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Gang Wen
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architectur and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
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4
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Morphology regulation and application of nano cobalt oxide (Co3O4) electrocatalysts for chlorine evolution toward marine anti-biofouling. J Colloid Interface Sci 2022; 628:794-806. [DOI: 10.1016/j.jcis.2022.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 07/21/2022] [Accepted: 08/01/2022] [Indexed: 11/22/2022]
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5
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Gupta V, Shekhawat SS, Kulshreshtha NM, Gupta AB. A systematic review on chlorine tolerance among bacteria and standardization of their assessment protocol in wastewater. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2022; 86:261-291. [PMID: 35906907 DOI: 10.2166/wst.2022.206] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Though chlorine is a cost-effective disinfectant for water and wastewaters, the bacteria surviving after chlorination pose serious public health and environmental problems. This review critically assesses the mechanism of chlorine disinfection as described by various researchers; factors affecting chlorination efficacy; and the re-growth potential of microbial contaminations in treated wastewater post chlorination to arrive at meaningful doses for ensuring health safety. Literature analysis shows procedural inconsistencies in the assessment of chlorine tolerant bacteria, making it extremely difficult to compare the tolerance characteristics of different reported tolerant bacteria. A comparison of logarithmic reduction after chlorination and the concentration-time values for prominent pathogens led to the generation of a standard protocol for the assessment of chlorine tolerance. The factors that need to be critically monitored include applied chlorine doses, contact time, determination of chlorine demands of the medium, and the consideration of bacterial counts immediately after chlorination and in post chlorinated samples (regrowth). The protocol devised here appropriately assesses the chlorine-tolerant bacteria and urges the scientific community to report the regrowth characteristics as well. This would increase the confidence in data interpretation that can provide a better understanding of chlorine tolerance in bacteria and aid in formulating strategies for effective chlorination.
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Affiliation(s)
- Vinayak Gupta
- Alumnus, Department of Civil and Environmental Engineering, National University of Singapore, Singapore; School of Environment and Society, Tokyo Institute of Technology, Tokyo, Japan
| | - Sandeep Singh Shekhawat
- Department of Civil Engineering, Malaviya National Institute of Technology, Jaipur, India E-mail: ; School of Life and Basic Sciences, SIILAS Campus, Jaipur National University Jaipur, India
| | - Niha Mohan Kulshreshtha
- Department of Civil Engineering, Malaviya National Institute of Technology, Jaipur, India E-mail:
| | - Akhilendra Bhushan Gupta
- Department of Civil Engineering, Malaviya National Institute of Technology, Jaipur, India E-mail:
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6
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Son HB, Bae WB, Jhee KH. Enhanced Antibacterial Activity of Sodium Hypochlorite under Acidic pH Condition. MICROBIOLOGY AND BIOTECHNOLOGY LETTERS 2022; 50:211-217. [DOI: 10.48022/mbl.2204.04014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 05/26/2022] [Accepted: 05/31/2022] [Indexed: 09/01/2023]
Affiliation(s)
- Hyeon-Bin Son
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea
| | - Won-Bin Bae
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea
| | - Kwang-Hwan Jhee
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea
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7
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Tao H, Liao Q, Xu YI, Wang HL. Efficacy of Slightly Acidic Electrolyzed Water for Inactivation of Cronobacter sakazakii and Biofilm Cells. J Food Prot 2022; 85:511-517. [PMID: 34882220 DOI: 10.4315/jfp-21-263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 12/03/2021] [Indexed: 11/11/2022]
Abstract
ABSTRACT The disinfection efficacy and mechanism of activity of slightly acidic electrolyzed water (SAEW) were investigated against Cronobacter sakazakii. Treatment with three concentrations of SAEW decreased C. sakazakii by 23 to 55% after 2 min. Propidium iodide uptake and scanning electron micrographs indicated that SAEW treatment damaged cell integrity and changed membrane permeability resulting in leakage of nucleic acids (109.7%), intercellular proteins (692.3%), and potassium ions (53.6%). The ability to form biofilms was also reduced. SAEW treatment reduced the activity of superoxide dismutase and catalase from 100.73 and 114.18 U/mg protein to 50.03 and 50.13 U/mg protein, respectively. Expression of C. sakazakii response regulator genes (katG, rpoS, phoP, glpK, dacC, and CSK29544_RS05515) was reduced, which blocked repair of osmotic stress-induced damage and inhibited biofilm formation. These findings provide insight into the effects of SAEW on bacterial genotype and phenotype. HIGHLIGHTS
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Affiliation(s)
- Han Tao
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, Hefei, Anhui 230009, People's Republic of China.,School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, People's Republic of China
| | - Qiaoming Liao
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, Hefei, Anhui 230009, People's Republic of China.,School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, People's Republic of China
| | - Y I Xu
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, Hefei, Anhui 230009, People's Republic of China
| | - Hui-Li Wang
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, Hefei, Anhui 230009, People's Republic of China.,School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, People's Republic of China
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8
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Antibacterial activity and mechanism of slightly acidic electrolyzed water against Shewanella putrefaciens and Staphylococcus saprophytic. Biochem Biophys Res Commun 2022; 592:44-50. [DOI: 10.1016/j.bbrc.2022.01.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 11/24/2022]
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9
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Sahu PK, Tilgam J, Mishra S, Hamid S, Gupta A, K J, Verma SK, Kharwar RN. Surface sterilization for isolation of endophytes: Ensuring what (not) to grow. J Basic Microbiol 2022; 62:647-668. [PMID: 35020220 DOI: 10.1002/jobm.202100462] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/29/2021] [Accepted: 12/31/2021] [Indexed: 12/19/2022]
Abstract
Endophytic microbiota opens a magnificent arena of metabolites that served as a potential source of medicines for treating a variety of ailments and having prospective uses in agriculture, food, cosmetics, and many more. There are umpteen reports of endophytes improving the growth and tolerance of plants. In addition, endophytes from lifesaving drug-producing plants such as Taxus, Nothapodytes, Catharanthus, and so forth have the ability to produce host mimicking compounds. To harness these benefits, it is imperative to isolate the true endophytes, not the surface microflora. The foremost step in endophyte isolation is the removal of epiphytic microbes from plant tissues, called as surface sterilization. The success of surface sterilization decides "what to grow" (the endophytes) and "what not to grow" (the epiphytes). It is very crucial to use an appropriate sterilant solution, concentration, and exposure time to ensure thorough surface disinfection with minimal damage to the endophytic diversity. Commonly used surface sterilants include sodium hypochlorite (2%-10%), ethanol (70%-90%), mercuric chloride (0.1%), formaldehyde (40%), and so forth. In addition, the efficiency could further be improved by pretreatment with surfactants such as Triton X-100, Tween 80, and Tween 20. This review comprehensively deals with the various sterilants and sterilization methods for the isolation of endophytic microbes. In addition, the mechanisms and rationale behind using specific surface sterilants have also been elaborated at length.
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Affiliation(s)
- Pramod K Sahu
- ICAR-National Bureau of Agriculturally Important Microorganisms, Kushmaur, Maunath Bhanjan, Uttar Pradesh, India
| | - Jyotsana Tilgam
- ICAR-National Bureau of Agriculturally Important Microorganisms, Kushmaur, Maunath Bhanjan, Uttar Pradesh, India
| | - Sushma Mishra
- Plant Biotechnology Laboratory, Dayalbagh Educational Institute (Deemed-to-be-University), Agra, Uttar Pradesh, India
| | - Saima Hamid
- Department of Plant Biotechnology and Microbial Ecology, University of Kashmir, Hazratbal, Srinagar, Jammu & Kashmir, India
| | - Amrita Gupta
- Department of Biotechnology, Amity Institute of Biotechnology, Amity University, Lucknow, Uttar Pradesh, India
| | - Jayalakshmi K
- ICAR-National Bureau of Agriculturally Important Microorganisms, Kushmaur, Maunath Bhanjan, Uttar Pradesh, India
| | - Satish K Verma
- Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Ravindra N Kharwar
- Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India
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10
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Jiang B, Zeng Q, Hou Y, Li H, Shi S, Chen Z, Cui Y, Hu D, Ge H, Che S, Sui Y, Qi Y. The responses of activated sludge to membrane cleaning reagent H 2O 2 and protection of extracellular polymeric substances. ENVIRONMENTAL RESEARCH 2022; 203:111817. [PMID: 34352233 DOI: 10.1016/j.envres.2021.111817] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 07/29/2021] [Accepted: 07/29/2021] [Indexed: 06/13/2023]
Abstract
Hydrogen peroxide (H2O2) is evaluated as a potential replacement for chlorine to control biofouling in membrane bioreactors (MBRs). However, H2O2 might diffuse into the mixed liquor and damage microorganisms during membrane cleaning. This study comprehensively analyzed the impacts of H2O2 on microbes. Key enzymes involved in phenol biodegradation were inhibited with H2O2 concentration increased, and thus phenol degradation efficiency was decreased. Increase of lactic dehydrogenase (LDH) and intracellular reactive oxygen species (ROS) indicated more severe cell rupture with H2O2 concentration increased. At the same H2O2 concentration, Extracellular polymeric substances (EPS) extraction further led to inhibiting the activity of key enzymes, decreasing phenol degradation efficiency, and enhancing LDH release and ROS production, demonstrating that the existence of EPS moderated the adverse impacts on microbes. Spectroscopic characterization revealed the increase of H2O2 decreased tryptophan protein-like substances, protein-associated bonds and polysaccharide-associated bonds. Hydroxyl and amide groups in EPS were attacked, which might lead to the consumption of H2O2, indicated EPS protect the microorganism through sacrificial reaction with H2O2.
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Affiliation(s)
- Bei Jiang
- Key Laboratory of Biotechnology and Bioresources Utilization, Ministry of Education, Dalian Minzu University, Dalian, 116600, China; College of Environment and Resources, Dalian Minzu University, Dalian, 116600, China.
| | - Qianzhi Zeng
- School of Life Science, Liaoning Normal University, Dalian, 116081, China
| | - Yuan Hou
- School of Life Science, Liaoning Normal University, Dalian, 116081, China
| | - Hongxin Li
- School of Life Science, Liaoning Normal University, Dalian, 116081, China
| | - Shengnan Shi
- School of Life Science, Liaoning Normal University, Dalian, 116081, China
| | - Zhaobo Chen
- Key Laboratory of Biotechnology and Bioresources Utilization, Ministry of Education, Dalian Minzu University, Dalian, 116600, China; College of Environment and Resources, Dalian Minzu University, Dalian, 116600, China
| | - Yubo Cui
- Key Laboratory of Biotechnology and Bioresources Utilization, Ministry of Education, Dalian Minzu University, Dalian, 116600, China; College of Environment and Resources, Dalian Minzu University, Dalian, 116600, China
| | - Dongxue Hu
- Key Laboratory of Biotechnology and Bioresources Utilization, Ministry of Education, Dalian Minzu University, Dalian, 116600, China; College of Environment and Resources, Dalian Minzu University, Dalian, 116600, China
| | - Hui Ge
- Key Laboratory of Biotechnology and Bioresources Utilization, Ministry of Education, Dalian Minzu University, Dalian, 116600, China; College of Environment and Resources, Dalian Minzu University, Dalian, 116600, China
| | - Shun Che
- Yingkou Port Group CORP, Yingkou, 115007, China
| | - Yanan Sui
- Yingkou Port Group CORP, Yingkou, 115007, China
| | - Yu Qi
- Yingkou Port Group CORP, Yingkou, 115007, China
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11
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Visconti V, Coton E, Rigalma K, Dantigny P. Effects of disinfectants on inactivation of mold spores relevant to the food industry: a review. FUNGAL BIOL REV 2021. [DOI: 10.1016/j.fbr.2021.09.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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Oxidative Stress Response in Pseudomonas aeruginosa. Pathogens 2021; 10:pathogens10091187. [PMID: 34578219 PMCID: PMC8466533 DOI: 10.3390/pathogens10091187] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/06/2021] [Accepted: 09/08/2021] [Indexed: 12/17/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative environmental and human opportunistic pathogen highly adapted to many different environmental conditions. It can cause a wide range of serious infections, including wounds, lungs, the urinary tract, and systemic infections. The high versatility and pathogenicity of this bacterium is attributed to its genomic complexity, the expression of several virulence factors, and its intrinsic resistance to various antimicrobials. However, to thrive and establish infection, P. aeruginosa must overcome several barriers. One of these barriers is the presence of oxidizing agents (e.g., hydrogen peroxide, superoxide, and hypochlorous acid) produced by the host immune system or that are commonly used as disinfectants in a variety of different environments including hospitals. These agents damage several cellular molecules and can cause cell death. Therefore, bacteria adapt to these harsh conditions by altering gene expression and eliciting several stress responses to survive under oxidative stress. Here, we used PubMed to evaluate the current knowledge on the oxidative stress responses adopted by P. aeruginosa. We will describe the genes that are often differently expressed under oxidative stress conditions, the pathways and proteins employed to sense and respond to oxidative stress, and how these changes in gene expression influence pathogenicity and the virulence of P. aeruginosa. Understanding these responses and changes in gene expression is critical to controlling bacterial pathogenicity and developing new therapeutic agents.
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13
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Nagamatsu Y, Nagamatsu H, Ikeda H, Shimizu H. Microbicidal effect and storage stability of neutral HOCl-containing aqueous gels with different thickening/gelling agents. Dent Mater J 2021; 40:1309-1319. [PMID: 34193729 DOI: 10.4012/dmj.2020-454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Electrolyzed waters, containing mainly hypochlorous acid, are used in dental practice because of their high microbicidal effect. For wider use, three neutral electrolyzed water-based gels, namely, HOCl-containing aqueous gels were prepared with a thickening/gelling agent in this study. We evaluated their microbicidal effects against four strains and storage stabilities indicated by available chlorine concentration. Immediately after preparation, all gels (70 ppm) could completely remove microbes by a 3-min treatment. The gel prepared with xanthan gum remarkably reduced its available chlorine concentration even under shaded and refrigerated storage conditions, failing to maintain its microbicidal effect following 1-day storage, whereas other gels, prepared with carboxyvinyl polymer or agar, maintained effective concentration (>20 ppm), with high microbicidal effects following 9-day and 21-day storage, respectively. Neutral electrolyzed water-based gels might be useful to remove oral microbes. Based on our results, agar is the most suitable thickening/gelling agent from the viewpoint of storage stability.
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Affiliation(s)
- Yuki Nagamatsu
- Division of Biomaterials, Department of Oral Functions, Kyushu Dental University
| | - Hiroshi Nagamatsu
- Division of Comprehensive Dentistry, Department of Oral Functions, Kyushu Dental University
| | - Hiroshi Ikeda
- Division of Biomaterials, Department of Oral Functions, Kyushu Dental University
| | - Hiroshi Shimizu
- Division of Biomaterials, Department of Oral Functions, Kyushu Dental University
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14
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da Cruz Nizer WS, Inkovskiy V, Overhage J. Surviving Reactive Chlorine Stress: Responses of Gram-Negative Bacteria to Hypochlorous Acid. Microorganisms 2020; 8:E1220. [PMID: 32796669 PMCID: PMC7464077 DOI: 10.3390/microorganisms8081220] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 07/30/2020] [Accepted: 08/09/2020] [Indexed: 01/29/2023] Open
Abstract
Sodium hypochlorite (NaOCl) and its active ingredient, hypochlorous acid (HOCl), are the most commonly used chlorine-based disinfectants. HOCl is a fast-acting and potent antimicrobial agent that interacts with several biomolecules, such as sulfur-containing amino acids, lipids, nucleic acids, and membrane components, causing severe cellular damage. It is also produced by the immune system as a first-line of defense against invading pathogens. In this review, we summarize the adaptive responses of Gram-negative bacteria to HOCl-induced stress and highlight the role of chaperone holdases (Hsp33, RidA, Cnox, and polyP) as an immediate response to HOCl stress. We also describe the three identified transcriptional regulators (HypT, RclR, and NemR) that specifically respond to HOCl. Besides the activation of chaperones and transcriptional regulators, the formation of biofilms has been described as an important adaptive response to several stressors, including HOCl. Although the knowledge on the molecular mechanisms involved in HOCl biofilm stimulation is limited, studies have shown that HOCl induces the formation of biofilms by causing conformational changes in membrane properties, overproducing the extracellular polymeric substance (EPS) matrix, and increasing the intracellular concentration of cyclic-di-GMP. In addition, acquisition and expression of antibiotic resistance genes, secretion of virulence factors and induction of the viable but nonculturable (VBNC) state has also been described as an adaptive response to HOCl. In general, the knowledge of how bacteria respond to HOCl stress has increased over time; however, the molecular mechanisms involved in this stress response is still in its infancy. A better understanding of these mechanisms could help understand host-pathogen interactions and target specific genes and molecules to control bacterial spread and colonization.
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Affiliation(s)
| | | | - Joerg Overhage
- Department of Health Sciences, Carleton University, Ottawa, ON K1S 5B6, Canada; (W.S.d.C.N.); (V.I.)
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15
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Naka A, Yakubo M, Nakamura K, Kurahashi M. Effectiveness of slightly acidic electrolyzed water on bacteria reduction: in vitro and spray evaluation. PeerJ 2020; 8:e8593. [PMID: 32110494 PMCID: PMC7034383 DOI: 10.7717/peerj.8593] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 01/18/2020] [Indexed: 11/21/2022] Open
Abstract
Bacterial inactivation is a crucial aspect of sanitation and hygiene. The effectiveness of slightly acidic electrolyzed water (SAEW) for reduction or removal of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus epidermidis was evaluated. The bactericidal activity of SAEW and sodium hypochlorite (NaOCl) against E. coli and P. aeruginosa were compared through in vitro experiments. The effectiveness of SAEW spray was tested against S. epidermidis. Results showed that SAEW had a more powerful bactericidal activity than NaOCl at the same available chlorine concentrations. For E. coli, SAEW decreased the bacterial counts from 8.4 log10 CFU/mL to less than 3.9 log10 CFU/mL; NaOCl with the same available chlorine of 0.5 mg/L, caused a decrease from 8.4 log10 CFU/mL to 7.1 log10 CFU/mL. For P. aeruginosa, SAEW caused bacterial counts to decrease from 8.5 log10 CFU/mL to less than 4.1 log10 CFU/mL against 8.5 log10 CFU/mL to 6.2 log10 CFU/mL for NaOCl with the same available chlorine of 0.5 mg/L. Spray experiments showed that 10 mg/L of SAEW spray decreased the bacterial counts of S. epidermidis from 3.7 log10 CFU/m3 to 2.8 log10 CFU/m3, with 20 mg/L causing a reduction from 3.8 log10 CFU/m3 to 0 CFU/m3. The overall findings of this study indicate that SAEW may be a promising disinfectant agent either as a solution or spray.
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Affiliation(s)
- Angelica Naka
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Masaya Yakubo
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | | | - Midori Kurahashi
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
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Response of Freshwater Biofilms to Antibiotic Florfenicol and Ofloxacin Stress: Role of Extracellular Polymeric Substances. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16050715. [PMID: 30818877 PMCID: PMC6427337 DOI: 10.3390/ijerph16050715] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 02/16/2019] [Accepted: 02/21/2019] [Indexed: 11/16/2022]
Abstract
Antibiotic residues have been detected in aquatic environments worldwide. Biofilms are one of the most successful life forms, and as a result are ubiquitous in natural waters. However, the response mechanism of freshwater biofilms to the stress of various antibiotic residues is still unclear. Here, the stress of veterinary antibiotic florfenicol (FF) and fluoroquinolone antibiotic ofloxacin (OFL) on freshwater biofilms were investigated by determining the changes in the key physicochemical and biological properties of the biofilms. The results showed that the chlorophyll a content in biofilms firstly decreased to 46–71% and then recovered to original content under the stress of FF and OFL with high, mid, and low concentrations. Meanwhile, the activities of antioxidant enzymes, including superoxide dismutase and catalase, increased between 1.3–6.7 times their initial values. FF was more toxic to the biofilms than OFL. The distribution coefficients of FF and OFL binding in extracellular polymeric substances (EPS)-free biofilms were 3.2 and 6.5 times higher than those in intact biofilms, respectively. It indicated that EPS could inhibit the FF and OFL accumulation in biofilm cells. The present study shows that the EPS matrix, as the house of freshwater biofilms, is the primary barrier that resists the stress from antibiotic residues.
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Slightly acidic electrolyzed water disrupts biofilms and effectively disinfects Pseudomonas aeruginosa. J Infect Chemother 2019; 25:452-457. [PMID: 30782428 DOI: 10.1016/j.jiac.2019.01.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 01/21/2019] [Accepted: 01/28/2019] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Biofilm formation is an important issue in the healthcare industry, but conventional disinfectants are not effective for biofilms formed in the hospital environment and on medical instruments. In this study, aim at determine the effectiveness of slightly acidic electrolyzed water (SAEW) on biofilm removal and the disinfection of biofilm-forming Pseudomonas aeruginosa. METHODS Mucoid and non-mucoid strains were used for biofilm formation. Biofilms were incubated with SAEW and the reduction in biofilm volume was determined based on the optical density. Furthermore, to investigate the mechanism underlying the effects of SAEW, a biofilm was produced with alginate and structural changes in response to incubation with SAEW were observed by fluorescence microscopy. The minimum bactericidal chlorine concentration of SAEW for P. aeruginosa cells was evaluated. RESULTS The amounts of alginate and biofilm decreased by 99.9% and 56.8% immersed by 30 ppm of SAEW at 25 °C for 10 min. The effectiveness of SAEW increased as the temperature increased, and the biofilm volume was reduced by 85.4% at 45 °C. Furthermore, 30 ppm SAEW completely disinfected P. aeruginosa in the biofilm, even for immersion at 15 °C for 5 min. CONCLUSION Our results suggest that SAEW, a low-cost and safe chlorine disinfectant, is a useful disinfectant for biofilm-forming bacteria.
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Wang J, Sui M, Yuan B, Li H, Lu H. Inactivation of two Mycobacteria by free chlorine: Effectiveness, influencing factors, and mechanisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 648:271-284. [PMID: 30118940 DOI: 10.1016/j.scitotenv.2018.07.451] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/24/2018] [Accepted: 07/30/2018] [Indexed: 05/10/2023]
Abstract
Chlorination is one of the most widely used disinfection techniques, and the problem of "chlorine-resistant bacteria" (CRB) has attracted more attention recently. In this study, the deactivation of typical CRB in water, Mycobacterium fortuitum (M. fortuitum) and Mycobacterium mucogenicum (M. mucogenicum), by free chlorine was investigated with Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) as the reference. The chlorination effectiveness of chlorine on M. fortuitum and M. mucogenicum and the effect of chlorine concentration, pH, and humic acid were studied. It was found that M. mucogenicum was more resistant to chlorine than M. fortuitum, both of which were much more resistant than E. coli and B. subtilis. The effect of disinfectant concentration on the inactivation efficiency was positive, whereas the influence of pH and humic acid was negative. The inactivation mechanisms were explored by analyzing the bacteria morphology, the destruction of cell membrane, the cell hydrophobicity, as well as total adenosine triphosphate (ATP), superoxide dismutase (SOD) activity. The slight destruction of the cell membrane was observed after deactivation with chlorine, and high hydrophobicity of the cell membrane combined with metabolic changes might lead to the chlorine tolerance of Mycobacteria.
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Affiliation(s)
- Jingyu Wang
- Shanghai Institute of Pollution Control and Ecological Security, State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, People's Republic of China
| | - Minghao Sui
- Shanghai Institute of Pollution Control and Ecological Security, State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, People's Republic of China.
| | - Bojie Yuan
- Shanghai Institute of Pollution Control and Ecological Security, State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, People's Republic of China
| | - Hongwei Li
- Shanghai Institute of Pollution Control and Ecological Security, State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, People's Republic of China
| | - Hongtao Lu
- Shanghai Institute of Pollution Control and Ecological Security, State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, People's Republic of China
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Wang L, Li Y, Wang L, Zhang H, Zhu M, Zhang P, Zhu X. Extracellular polymeric substances affect the responses of multi-species biofilms in the presence of sulfamethizole. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 235:283-292. [PMID: 29291528 DOI: 10.1016/j.envpol.2017.12.060] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 12/15/2017] [Accepted: 12/16/2017] [Indexed: 05/06/2023]
Abstract
The occurrence and transportation of antibiotics in biofilms from natural and engineered sources have attracted increasing interests. Nevertheless, the effects of extracellular polymeric substances (EPS) on the responses of biofilms to the exposure to antibiotics are not clear. In this study, the effects of EPS on the sorption and biological responses to one representative antibiotic, sulfamethizole (STZ), in model biofilms were investigated. Proteins dominated the interactions between the EPS and the STZ and the EPS from a moving bed biofilm reactor exhibited the strongest interaction with the STZ. The EPS served as important reservoirs for the STZ and the tested biofilms all showed reduced sorption capacities for the STZ after the EPS were extracted. The respiratory rates and typical enzymatic activities were reduced after the EPS were extracted. High-throughput 16S rRNA gene sequencing results confirmed that the bacterial community in the biofilm without the EPS was more vulnerable to antibiotic shock as indicated by the community diversity and richness indices. A greater increase in the abundance of susceptible species was observed in the natural biofilm. The results comprehensively suggested that the EPS played important role in biosorption of STZ and alleviated the direct damage of the antibiotic to the cells; in addition the extent of the bacterial community response was associated with the origins of the biofilms. Our study provided details on the responses of multi-species biofilms to the exposure to an antibiotic and highlighted the role of the EPS in interacting with the antibiotic, thereby providing a deeper understanding of the bioremediation of antibiotics in real-life natural and engineered biofilm systems.
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Affiliation(s)
- Longfei Wang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210098, PR China
| | - Yi Li
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210098, PR China.
| | - Li Wang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210098, PR China
| | - Huanjun Zhang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210098, PR China
| | - Mengjie Zhu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210098, PR China
| | - Peisheng Zhang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210098, PR China
| | - Xiaoxiao Zhu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210098, PR China
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Takahashi K, Tanaka R, Fukuzaki S. Kinetics of the Inactivation of Vibrio parahaemolyticus in Weakly Acidic Sodium Chlorite Solution. Biocontrol Sci 2017; 22:25-30. [PMID: 28367867 DOI: 10.4265/bio.22.25] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
The kinetics of the inactivation of Vibrio parahaemolyticus in sodium chlorite (NaClO2) solution was studied in the weakly acidic pH range of 4.0 to 6.5 and at various temperatures. The logarithmic reduction of the survival ratio depended on the concentration-time product, and all the inactivation curves showed a linear reduction phase. The first-order inactivation rate constant (k) increased by approximately twice for every 0.44 unit fall in pH. During the inactivation experiments, no formation of chlorine dioxide occurred. These data indicated that undissociated HClO2 was the active species governing the inactivation of V. parahaemolyticus. It was also shown that the use of weakly acidic NaClO2 solutions containing high concentrations of ionized ClO2- gave slower kinetics of the inactivation, whereas it could achieve the significant reduction of viable cells of more than 4-log. The k value showed an Arrhenius-type temperature dependence in the temperature range of 5 to 40℃. The apparent activation energy for the inactivation of V. parahaemolyticus was estimated to be 43.5 kJ/mol. The k value increased by approximately 1.8 times for every 10℃ rise in temperature.
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Han X, Wang Z, Chen M, Zhang X, Tang CY, Wu Z. Acute Responses of Microorganisms from Membrane Bioreactors in the Presence of NaOCl: Protective Mechanisms of Extracellular Polymeric Substances. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:3233-3241. [PMID: 28263585 DOI: 10.1021/acs.est.6b05475] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Extracellular polymeric substances (EPS) are key foulants in membrane bioreactors (MBRs). However, their positive functions of protecting microorganisms from environmental stresses, e.g., during in situ hypochlorite chemical cleaning of membranes, have not been adequately elucidated. In this work, we investigated the response of microorganisms in an MBR to various dosages of NaOCl, with a particular emphasis on the mechanistic roles of EPS. Results showed that functional groups in EPS such as the hydroxyl and amino groups were attacked by NaOCl, causing the oxidation of polysaccharides, denaturation of amino acids, damage to protein secondary structure, and transformation of tryptophan protein-like substances to condensed aromatic ring substances. The presence of EPS alleviated the negative impacts on catalase and superoxide dismutase, which in turn reduced the concentration of reactive oxygen species (ROS) in microbial cells. The direct extracellular reaction and the mitigated intracellular oxidative responses facilitated the maintenance of microbial metabolism, as indicated by the quantity of adenosine triphosphate and the activity of dehydrogenase. The reaction with NaOCl also led to the changes of cell integrity and adhesion properties of EPS, which promoted the release of organic matter into bulk solution. Our results systematically demonstrate the protective roles of EPS and the underlying mechanisms in resisting the environmental stress caused by NaOCl, which provides important implications for in situ chemical cleaning in MBRs.
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Affiliation(s)
- Xiaomeng Han
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University , 1239 Siping Road, Shanghai 200092, China
- Shanghai Urban Water Resources Development and Utilization National Engineering Center Co. Ltd. , Shanghai 200082, China
| | - Zhiwei Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University , 1239 Siping Road, Shanghai 200092, China
| | - Mei Chen
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University , 1239 Siping Road, Shanghai 200092, China
| | - Xingran Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University , 1239 Siping Road, Shanghai 200092, China
| | - Chuyang Y Tang
- Department of Civil Engineering, The University of Hong Kong , Pokfulam, Hong Kong China
| | - Zhichao Wu
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University , 1239 Siping Road, Shanghai 200092, China
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Xu Z, Liu Y, Williams I, Li Y, Qian F, Zhang H, Cai D, Wang L, Li B. Disposable self-support paper-based multi-anode microbial fuel cell (PMMFC) integrated with power management system (PMS) as the real time “shock” biosensor for wastewater. Biosens Bioelectron 2016; 85:232-239. [DOI: 10.1016/j.bios.2016.05.018] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 05/03/2016] [Accepted: 05/05/2016] [Indexed: 11/26/2022]
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Novoa-Luna KA, Mendoza-Zepeda A, Natividad R, Romero R, Galar-Martínez M, Gómez-Oliván LM. Biological hazard evaluation of a pharmaceutical effluent before and after a photo-Fenton treatment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 569-570:830-840. [PMID: 27392336 DOI: 10.1016/j.scitotenv.2016.06.086] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 06/03/2016] [Accepted: 06/13/2016] [Indexed: 06/06/2023]
Abstract
The aim of this study was to evaluate the biological hazard of a pharmaceutical effluent before and after treatment. For the former, the determined 96h-LC50 value was 1.2%. The photo-Fenton treatment catalyzed with an iron-pillared clay reduced this parameter by 341.7%. Statistically significant increases with respect to the control group (P<0.05) were observed at 12, 24, 48 and 72h in HPC (50.2, 30.4, 66.9 and 43.3%), LPX (22, 83.2, 62.7 and 59.5%) and PCC (14.6, 23.6, 24.4 and 25.6%) and antioxidant enzymes SOD (29.4, 38.5, 32.7 and 49.5%) and CAT (48.4, 50.3, 38.8 and 46.1%) in Hyalella azteca before treatment. Also increases in damage index were observed before treatment of 53.1, 59.9, 66.6 and 72.1% at 12, 24, 48 and 72h, respectively. After treatment the same biomarkers of oxidative stress decreased with respect to before treatment being to HPC (29.3, 22.5, 41.6 and 31.7%); LPX (14.2, 43.1, 30.7 and 35.5%); PCC (12.6, 21.3, 24.2 and 23.9%); SOD (39.2, 33.9, 49.5 and 37.9%) and CAT (28.6, 35.8, 33.7 and 31.7) at 12, 24, 48 and 72h, respectively (P<0.05). The damage index were decreased at 12, 24, 48 and 72h in 48.9, 57.8, 67.3 and 72.1%, respectively. In conclusion, the obtained results demonstrate the need of performing bioassays in order to characterize an effluent before discharge and not base such a decision only upon current normativity. In addition, it was also concluded that the heterogeneous photo-Fenton process decreases the presence of PCT, oxidative stress, genotoxic damage and LC50 in Hyalella azteca.
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Affiliation(s)
- Karen Adriana Novoa-Luna
- Laboratorio de Toxicología Ambiental, Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón intersección Paseo Tollocan s/n. Col. Residencial Colón, 50120 Toluca, Estado de México, Mexico
| | - Arisbeht Mendoza-Zepeda
- Chemical Engineering Lab., Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco Km 14.5, Unidad San Cayetano, Toluca, Estado de México 50200, Mexico
| | - Reyna Natividad
- Chemical Engineering Lab., Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco Km 14.5, Unidad San Cayetano, Toluca, Estado de México 50200, Mexico
| | - Rubi Romero
- Chemical Engineering Lab., Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco Km 14.5, Unidad San Cayetano, Toluca, Estado de México 50200, Mexico
| | - Marcela Galar-Martínez
- Laboratorio de Toxicología Acuática, Departamento de Farmacia, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Unidad Profesional Adolfo López Mateos, Av. Wilfrido Massieu s/n y Cerrada de Manuel Stampa, Col. Industrial Vallejo, C.P. 007700 México, D.F., Mexico
| | - Leobardo Manuel Gómez-Oliván
- Laboratorio de Toxicología Ambiental, Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón intersección Paseo Tollocan s/n. Col. Residencial Colón, 50120 Toluca, Estado de México, Mexico.
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Novoa-Luna KA, Romero-Romero R, Natividad-Rangel R, Galar-Martínez M, SanJuan-Reyes N, García-Medina S, Martínez-Vieyra C, Neri-Cruz N, Gómez-Oliván LM. Oxidative stress induced in Hyalella azteca by an effluent from a NSAID-manufacturing plant in Mexico. ECOTOXICOLOGY (LONDON, ENGLAND) 2016; 25:1288-1304. [PMID: 27256318 DOI: 10.1007/s10646-016-1682-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/25/2016] [Indexed: 06/05/2023]
Abstract
Production in the pharmaceutical industry has increased and along with it, the amount of wastewater of various characteristics and contaminant concentrations. The main chemicals in these effluents are solvents, detergents, disinfectants-such as sodium hypochlorite (NaClO)-and pharmaceutical products, all of which are potentially ecotoxic. Therefore, this study aimed to evaluate the oxidative stress induced in the amphipod Hyalella azteca by the effluent from a nonsteroidal anti-inflammatory drug (NSAID)-manufacturing plant. The median lethal concentration (72 h-LC50) was determined and H. azteca were exposed to the lowest observed adverse effect level (0.0732 %) for 12, 24, 48 and 72 h, and biomarkers of oxidative stress were evaluated [hydroperoxide content (HPC), lipid peroxidation (LPX), protein carbonyl content (PCC), and the activity of the superoxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)]. Statistically significant increases with respect to the control group (P < 0.05) were observed in HPC, LPX and PCC in H. azteca at all exposure times. Antioxidant enzymes activity SOD, CAT and GPx activity also increased significantly (P < 0.05) with respect to the control group. In conclusion, the industrial effluent analyzed in the present study contains NSAIDs and NaClO, and induces oxidative stress in H. azteca.
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Affiliation(s)
- Karen Adriana Novoa-Luna
- Laboratorio de Toxicología Ambiental, Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón intersección Paseo Tollocan s/n. Col. Residencial Colón, 50120, Toluca, State of Mexico, Mexico
| | - Rubí Romero-Romero
- Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco Km 14.5, Unidad San Cayetano, 50200, Toluca, State of Mexico, Mexico
| | - Reyna Natividad-Rangel
- Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco Km 14.5, Unidad San Cayetano, 50200, Toluca, State of Mexico, Mexico
| | - Marcela Galar-Martínez
- Laboratorio de Toxicología Acuática, Sección de Graduados e Investigación, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Plan de Ayala y Carpio s/n, 11340, Mexico, D.F., Mexico
| | - Nely SanJuan-Reyes
- Laboratorio de Toxicología Ambiental, Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón intersección Paseo Tollocan s/n. Col. Residencial Colón, 50120, Toluca, State of Mexico, Mexico
| | - Sandra García-Medina
- Laboratorio de Toxicología Acuática, Sección de Graduados e Investigación, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Plan de Ayala y Carpio s/n, 11340, Mexico, D.F., Mexico
| | - Catalina Martínez-Vieyra
- Laboratorio de Toxicología Ambiental, Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón intersección Paseo Tollocan s/n. Col. Residencial Colón, 50120, Toluca, State of Mexico, Mexico
| | - Nadia Neri-Cruz
- Laboratorio de Toxicología Ambiental, Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón intersección Paseo Tollocan s/n. Col. Residencial Colón, 50120, Toluca, State of Mexico, Mexico
| | - Leobardo Manuel Gómez-Oliván
- Laboratorio de Toxicología Ambiental, Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón intersección Paseo Tollocan s/n. Col. Residencial Colón, 50120, Toluca, State of Mexico, Mexico.
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Han X, Wang Z, Wang X, Zheng X, Ma J, Wu Z. Microbial responses to membrane cleaning using sodium hypochlorite in membrane bioreactors: Cell integrity, key enzymes and intracellular reactive oxygen species. WATER RESEARCH 2016; 88:293-300. [PMID: 26512807 DOI: 10.1016/j.watres.2015.10.033] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 09/24/2015] [Accepted: 10/17/2015] [Indexed: 06/05/2023]
Abstract
Sodium hypochlorite (NaClO) is a commonly used reagent for membrane cleaning in membrane bioreactors (MBRs), while it, being a kind of disinfectant (oxidant), may impair viability of microbes or even totally inactivate them upon its diffusion into mixed liquor during membrane cleaning. In this study, we systematically examine the effects of NaClO on microorganisms in terms of microbial cell integrity, metabolism behaviours (key enzymes), and intracellular reactive oxygen species (ROS) under various NaClO concentrations. Different proportions of microbial cells in activated sludge were damaged within several minutes dependent on NaClO dosages (5-50 mg/g-SS), and correspondingly organic matters were released to bulk solution. Inhibition of key enzymes involved in organic matter biodegradation, nitrification and denitrification was observed in the presence of NaClO above 1 mg/g-SS, and thus organic matter and nitrogen removal efficiencies were decreased. It was also demonstrated that intracellular ROS production was increased with the NaClO dosage higher than 1 mg/g-SS, which likely induced further damage to microbial cells.
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Affiliation(s)
- Xiaomeng Han
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China
| | - Zhiwei Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
| | - Xueye Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China
| | - Xiang Zheng
- School of Environment and Natural Resources, Renmin University of China, Beijing 100872, PR China
| | - Jinxing Ma
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China
| | - Zhichao Wu
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China
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Charoenlap N, Sornchuer P, Piwkam A, Srijaruskul K, Mongkolsuk S, Vattanaviboon P. The roles of peroxide protective regulons in protecting Xanthomonas campestris pv. campestris from sodium hypochlorite stress. Can J Microbiol 2015; 61:343-50. [DOI: 10.1139/cjm-2014-0792] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The exposure of Xanthomonas campestris pv. campestris to sublethal concentrations of a sodium hypochlorite (NaOCl) solution induced the expression of genes that encode peroxide scavenging enzymes within the OxyR and OhrR regulons. Sensitivity testing in various X. campestris mutants indicated that oxyR, katA, katG, ahpC, and ohr contributed to protection against NaOCl killing. The pretreatment of X. campestris cultures with oxidants, such as hydrogen peroxide (H2O2), t-butyl hydroperoxide, and the superoxide generator menadione, protected the bacteria from lethal concentrations of NaOCl in an OxyR-dependent manner. Treating the bacteria with a low concentration of NaOCl resulted in the adaptive protection from NaOCl killing and also provided cross-protection from H2O2 killing. Taken together, the results suggest that the toxicity of NaOCl is partially mediated by the generation of peroxides and other reactive oxygen species that are removed by primary peroxide scavenging enzymes, such as catalases and AhpC, as a part of an overall strategy that protects the bacteria from the lethal effects of NaOCl.
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Affiliation(s)
- Nisanart Charoenlap
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
| | - Phornphan Sornchuer
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
| | - Anong Piwkam
- Program in Applied Biological Science: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
| | - Kriangsuk Srijaruskul
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
| | - Skorn Mongkolsuk
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
- Department of Biotechnology and Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology, Commission on Higher Education, Ministry of Education, Bangkok, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
- Program in Applied Biological Science: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology, Commission on Higher Education, Ministry of Education, Bangkok, Thailand
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Mustapha P, Epalle T, Allegra S, Girardot F, Garraud O, Riffard S. Monitoring of Legionella pneumophila viability after chlorine dioxide treatment using flow cytometry. Res Microbiol 2015; 166:215-9. [DOI: 10.1016/j.resmic.2015.01.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 01/20/2015] [Accepted: 01/25/2015] [Indexed: 01/01/2023]
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Mokudai T, Kanno T, Niwano Y. Postantifungal-like effect of sublethal treatment of Candida albicans with acid-electrolyzed water. Arch Oral Biol 2015; 60:479-87. [PMID: 25555249 DOI: 10.1016/j.archoralbio.2014.12.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 10/08/2014] [Accepted: 12/10/2014] [Indexed: 11/20/2022]
Abstract
OBJECTIVE Acid-electrolyzed water (AEW) has been applied to the treatment of oral candidiasis. We evaluated the postantifungal effect (PAFE)-like activity of AEW against Candida albicans under sublethal conditions by exposing C. albicans to dilute AEW. DESIGN The growth of C. albicans after a short-term exposure to dilute AEW was evaluated in broth and on agar culture. The involvement of reactive oxygen species (ROS) in the PAFE was examined by flow cytometric analysis with hydroxyphenyl fluorescein (HPF) as a fluorescence probe. RESULTS The dilute AEW exerted PAFE-like activity against C. albicans. ROS were produced in the cells treated with AEW diluted 16 times or fewer. The increase in HPF fluorescence after treatment with dilute AEW was cancelled by dimethyl sulfoxide, a hydroxyl radical (OH) scavenger. CONCLUSION It would be expected that the ROS, especially OH, produced in the C. albicans cells treated with sublethal dilutions of AEW could exert PAFE-like activity against the fungal cells.
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Affiliation(s)
- Takayuki Mokudai
- Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Taro Kanno
- Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Yoshimi Niwano
- Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
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Ducret A, Chabalier M, Dukan S. Characterization and resuscitation of 'non-culturable' cells of Legionella pneumophila. BMC Microbiol 2014; 14:3. [PMID: 24383402 PMCID: PMC3882098 DOI: 10.1186/1471-2180-14-3] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 12/02/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Legionella pneumophila is a waterborne pathogen responsible for Legionnaires' disease, an infection which can lead to potentially fatal pneumonia. After disinfection, L. pneumophila has been detected, like many other bacteria, in a "viable but non culturable" state (VBNC). The physiological significance of the VBNC state is unclear and controversial: it could be an adaptive response favoring long-term survival; or the consequence of cellular deterioration which, despite maintenance of certain features of viable cells, leads to death; or an injured state leading to an artificial loss of culturability during the plating procedure. VBNC cells have been found to be resuscitated by contact with amoebae. RESULTS We used quantitative microscopic analysis, to investigate this "resuscitation" phenomenon in L. pneumophila in a model involving amending solid plating media with ROS scavengers (pyruvate or glutamate), and co-culture with amoebae. Our results suggest that the restoration observed in the presence of pyruvate and glutamate may be mostly due to the capacity of these molecules to help the injured cells to recover after a stress. We report evidence that this extracellular signal leads to a transition from a not-culturable form to a culturable form of L. pneumophila, providing a technique for recovering virulent and previously uncultivated forms of L. pneumophila. CONCLUSION These new media could be used to reduce the risk of underestimation of counts of virulent of L. pneumophila cells in environmental samples.
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Affiliation(s)
- Adrien Ducret
- Aix Marseille Université, Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée - CNRS, 31, Chemin Joseph Aiguier, 13402 Marseille, France
- Present address: Department of Biology, Indiana University, 1001 East 3rd Street, Bloomington, IN 47405 USA
| | - Maïalène Chabalier
- Aix Marseille Université, Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée - CNRS, 31, Chemin Joseph Aiguier, 13402 Marseille, France
| | - Sam Dukan
- Aix Marseille Université, Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée - CNRS, 31, Chemin Joseph Aiguier, 13402 Marseille, France
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Abstract
Hypochlorous acid (HOCl), the active ingredient of household bleach, is the most common disinfectant in medical, industrial, and domestic use and plays an important role in microbial killing in the innate immune system. Given the critical importance of the antimicrobial properties of chlorine to public health, it is surprising how little is known about the ways in which bacteria sense and respond to reactive chlorine species (RCS). Although the literature on bacterial responses to reactive oxygen species (ROS) is enormous, work addressing bacterial responses to RCS has begun only recently. Transcriptomic and proteomic studies now provide new insights into how bacteria mount defenses against this important class of antimicrobial compounds. In this review, we summarize the current knowledge, emphasizing the overlaps between RCS stress responses and other more well-characterized bacterial defense systems, and identify outstanding questions that represent productive avenues for future research.
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Affiliation(s)
- Michael J Gray
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1048; , ,
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Winterbourn CC, Kettle AJ. Redox reactions and microbial killing in the neutrophil phagosome. Antioxid Redox Signal 2013; 18:642-60. [PMID: 22881869 DOI: 10.1089/ars.2012.4827] [Citation(s) in RCA: 306] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
SIGNIFICANCE When neutrophils kill microorganisms, they ingest them into phagosomes and bombard them with a burst of reactive oxygen species. RECENT ADVANCES This review focuses on what oxidants are produced and how they kill. The neutrophil NADPH oxidase is activated and shuttles electrons from NADPH in the cytoplasm to oxygen in the phagosomal lumen. Superoxide is generated in the narrow space between the ingested organism and the phagosomal membrane and kinetic modeling indicates that it reaches a concentration of around 20 μM. Degranulation leads to a very high protein concentration with up to millimolar myeloperoxidase (MPO). MPO has many substrates, but its main phagosomal reactions should be to dismutate superoxide and, provided adequate chloride, catalyze efficient conversion of hydrogen peroxide to hypochlorous acid (HOCl). Studies with specific probes have shown that HOCl is produced in the phagosome and reacts with ingested bacteria. The amount generated should be high enough to kill. However, much of the HOCl reacts with phagosomal proteins. Generation of chloramines may contribute to killing, but the full consequences of this are not yet clear. CRITICAL ISSUES Isolated neutrophils kill most of the ingested microorganisms rapidly by an MPO-dependent mechanism that is almost certainly due to HOCl. However, individuals with MPO deficiency rarely have problems with infection. A possible explanation is that HOCl provides a frontline response that kills most of the microorganisms, with survivors killed by nonoxidative processes. The latter may deal adequately with low-level infection but with high exposure, more efficient HOCl-dependent killing is required. FUTURE DIRECTIONS Better quantification of HOCl and other oxidants in the phagosome should clarify their roles in antimicrobial action.
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Affiliation(s)
- Christine C Winterbourn
- Centre for Free Radical Research, Department of Pathology, University of Otago Christchurch, Christchurch, New Zealand.
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Ducret A, Dukan S. Single-cell analysis of cell viability after a biocide treatment unveils an absence of positive correlation between two commonly used viability markers. Microbiologyopen 2013; 2:123-9. [PMID: 23281341 PMCID: PMC3584218 DOI: 10.1002/mbo3.62] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 11/13/2012] [Accepted: 11/19/2012] [Indexed: 11/07/2022] Open
Abstract
Discrimination among viable/active or dead/inactive cells in a microbial community is a vital question to address issues on ecological microbiology or microbiological quality control. It is commonly assumed that metabolically active cells (ChemchromeV6 [CV6] procedure) correspond to viable cells (direct viable count procedure [DVC]), although this assumption has never been demonstrated and is therefore a matter of debate. Indeed, simultaneous determination of cell viability and metabolic activity has never been performed on the same cells. Here, we developed a microfluidic device to investigate the viability and the metabolic activity of Escherichia coli cells at single-cell level. Cells were immobilized in a flow chamber in which different solutions were sequentially injected according to different scenarios. By using time-lapse microscopy combined with automated tracking procedures, we first successfully assessed the ability of cells to divide and their metabolic activity at single-cell level. Applying these two procedures on the same cells after a hypochlorous acid (HOCl) treatment, we showed that the ability of cells to divide and their metabolic activity were anticorrelated. These results indicate that the relation between CV6 uptake and cell viability may be partially incorrect. Care must be taken in using the terms "CV6-positive" and "viable" synonymously.
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Affiliation(s)
- Adrien Ducret
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée-Université Aix-Marseille, CNRS UMR7283, 31 Chemin Joseph Aiguier, Marseille, 13009, France
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33
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Variability of the tandem repeat region of the Escherichia coli tolA gene. Res Microbiol 2012; 163:316-22. [DOI: 10.1016/j.resmic.2012.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 05/03/2012] [Indexed: 11/23/2022]
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Gaupp R, Ledala N, Somerville GA. Staphylococcal response to oxidative stress. Front Cell Infect Microbiol 2012; 2:33. [PMID: 22919625 PMCID: PMC3417528 DOI: 10.3389/fcimb.2012.00033] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 02/29/2012] [Indexed: 12/23/2022] Open
Abstract
Staphylococci are a versatile genus of bacteria that are capable of causing acute and chronic infections in diverse host species. The success of staphylococci as pathogens is due in part to their ability to mitigate endogenous and exogenous oxidative and nitrosative stress. Endogenous oxidative stress is a consequence of life in an aerobic environment; whereas, exogenous oxidative and nitrosative stress are often due to the bacteria's interaction with host immune systems. To overcome the deleterious effects of oxidative and nitrosative stress, staphylococci have evolved protection, detoxification, and repair mechanisms that are controlled by a network of regulators. In this review, we summarize the cellular targets of oxidative stress, the mechanisms by which staphylococci sense oxidative stress and damage, oxidative stress protection and repair mechanisms, and regulation of the oxidative stress response. When possible, special attention is given to how the oxidative stress defense mechanisms help staphylococci control oxidative stress in the host.
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Affiliation(s)
- Rosmarie Gaupp
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln NE, USA
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Bodet C, Sahr T, Dupuy M, Buchrieser C, Héchard Y. Legionella pneumophila transcriptional response to chlorine treatment. WATER RESEARCH 2012; 46:808-816. [PMID: 22192759 DOI: 10.1016/j.watres.2011.11.059] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 11/18/2011] [Accepted: 11/19/2011] [Indexed: 05/31/2023]
Abstract
Legionella pneumophila is a ubiquitous environmental microorganism found in freshwater that can cause an acute form of pneumonia known as Legionnaires' disease. Despite widespread use of chlorine to ensure drinking water quality and awareness that L. pneumophila may escape these treatments, little is known about its effects on L. pneumophila. The aim of this study was to investigate the L. pneumophila transcriptional response induced by chlorine treatment. Transcriptome analysis, using DNA arrays, showed that a sublethal dose of chlorine induces a differential expression of 391 genes involved in stress response, virulence, general metabolism, information pathways and transport. Many of the stress response genes were significantly upregulated, whereas a significant number of virulence genes were repressed. In particular, exposure of L. pneumophila to chlorine induced the expression of cellular antioxidant proteins, stress proteins and transcriptional regulators. In addition, glutathione S-transferase specific activity was enhanced following chlorine treatment. Our results clearly indicate that chlorine induces expression of proteins involved in cellular defence mechanisms against oxidative stress that might be involved in adaptation or resistance to chlorine treatment.
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Affiliation(s)
- Charles Bodet
- Laboratoire de Chimie et Microbiologie de l'Eau, UMR 6008, Université de Poitiers, 40 avenue du Recteur Pineau, 86022 Poitiers Cedex, France.
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Issa-Zacharia A, Kamitani Y, Miwa N, Muhimbula H, Iwasaki K. Application of slightly acidic electrolyzed water as a potential non-thermal food sanitizer for decontamination of fresh ready-to-eat vegetables and sprouts. Food Control 2011. [DOI: 10.1016/j.foodcont.2010.10.011] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Phe MH, Hajj Chehade M, Guilloteau H, Merlin C, Block JC. Assessment of Damage to Nucleic Acids and Repair Machinery in Salmonella typhimurium Exposed to Chlorine. Int J Microbiol 2009; 2009:201868. [PMID: 19936107 PMCID: PMC2777018 DOI: 10.1155/2009/201868] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Revised: 03/14/2009] [Accepted: 04/13/2009] [Indexed: 11/17/2022] Open
Abstract
Water disinfection is usually evaluated using mandatory methods based on cell culturability. However, such methods do not consider the potential of cells to recover, which should also be kept as low as possible. In this paper, we hypothesized that a successful disinfection is achieved only when the applied chlorine leads to both intracellular nucleic acid damage and strong alterations of the DNA repair machinery. Monitoring the SOS system responsiveness with a umuC'-'lacZ reporter fusion, we found that the expression of this important cellular machinery was altered after the beginning of membrane permeabilization but prior to the total decline of both the cell culturability and the nucleic acid integrity as revealed by Sybr-II staining. Rapid measurement of such nucleic acid alterations by fluorochrome-based staining could be used as an alternative method for assessing the effectiveness of disinfection with chlorine.
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Affiliation(s)
- M. H. Phe
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), UMR 7564 CNRS, Nancy-Université, 405 rue de Vandoeuvre, 54600 Villers-lès-Nancy, France
| | - M. Hajj Chehade
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), UMR 7564 CNRS, Nancy-Université, 405 rue de Vandoeuvre, 54600 Villers-lès-Nancy, France
| | - H. Guilloteau
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), UMR 7564 CNRS, Nancy-Université, 405 rue de Vandoeuvre, 54600 Villers-lès-Nancy, France
| | - C. Merlin
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), UMR 7564 CNRS, Nancy-Université, 405 rue de Vandoeuvre, 54600 Villers-lès-Nancy, France
| | - J. C. Block
- Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), UMR 7564 CNRS, Nancy-Université, 405 rue de Vandoeuvre, 54600 Villers-lès-Nancy, France
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Kang JI, Neidigh JW. Hypochlorous acid damages histone proteins forming 3-chlorotyrosine and 3,5-dichlorotyrosine. Chem Res Toxicol 2008; 21:1028-38. [PMID: 18452314 DOI: 10.1021/tx7003486] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
While the last 30 years chronicles an extensive effort to understand the damage to DNA caused by reactive oxygen species (ROS), little research has examined the chemical damage to the histone proteins found in chromatin. Hypochlorous acid (HOCl), the primary product of activated neutrophils, is known to damage both DNA and proteins. This article describes the use of mass spectrometry to quantitate the formation of 3-chlorotyrosine and 3,5-dichlorotyrosine, stable and unique markers of protein damage caused by HOCl, in the core histone proteins. Our results indicate that up to 25% of the tyrosine in histone proteins become chlorinated by excess HOCl. We also observe significant formation of 3-chlorotyrosine and 3,5-dichlorotyrosine at low HOCl concentrations and short reaction times. We use mass spectrometry to identify the tyrosine residues on each histone protein that are chlorinated based on the observation of chlorine-containing peptides following protease digestion of histone proteins exposed to HOCl. The tyrosine residues preferentially chlorinated by HOCl are generally within three residues of a lysine or histidine residue, further implicating the initial formation of chloramines in the efficient chlorination of tyrosine residues. The methods and results described here should further our understanding of how HOCl produced at sites of inflammation might damage chromatin.
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Affiliation(s)
- Joseph I Kang
- Department of Basic Sciences, Biochemistry Division, Loma Linda University, School of Medicine, Loma Linda, California 92350, USA.
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40
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Lyon DY, Brunet L, Hinkal GW, Wiesner MR, Alvarez PJJ. Antibacterial activity of fullerene water suspensions (nC60) is not due to ROS-mediated damage. NANO LETTERS 2008; 8:1539-43. [PMID: 18410152 DOI: 10.1021/nl0726398] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The cytotoxic and antibacterial properties of nC 60, a buckminsterfullerene water suspension, have been attributed to photocatalytically generated reactive oxygen species (ROS). However, in this work, neither ROS production nor ROS-mediated damage is found in nC 60-exposed bacteria. Furthermore, the colorimetric methods used to evaluate ROS production and damage are confounded by interactions between nC 60 and the reagents, yielding false positives. Instead, we propose that nC 60 exerts ROS-independent oxidative stress, thus reconciling conflicting results in the literature.
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Affiliation(s)
- Delina Y Lyon
- Department of Civil and Environmental Engineering, Rice University, 6100 Main Street, Houston, Texas 77005, USA
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Chang MW, Toghrol F, Bentley WE. Toxicogenomic response to chlorination includes induction of major virulence genes in Staphylococcus aureus. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2007; 41:7570-7575. [PMID: 18044543 DOI: 10.1021/es070929k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Despite the widespread use of chlorination for microbial control in aqueous environments, cellular response mechanisms of human pathogens, such as Staphylococcus aureus, against chlorination remain unknown. In this work, genome-wide transcriptional analysis was performed to elucidate cellular response of S. aureusto hypochlorous acid, an active antimicrobial product of chlorination in aqueous solution. Our results suggest that hypochlorous acid repressed transcription of genes involved in cell wall synthesis, membrane transport, protein synthesis, and primary metabolism, while amino acid synthesis genes were induced. Furthermore, hypochlorous acid induced transcription of genes encoding major virulence factors of S. aureus, such as exotoxins, hemolysins, leukocidins, coagulases, and surface adhesion proteins, which all play essential roles in staphylococcal virulence. This work implies that chlorination may stimulate production of virulence factors, which provides new insight into host-pathogen interactions and effects of chlorine application for microbial control.
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Affiliation(s)
- Matthew Wook Chang
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore
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TiO2 photocatalysis causes DNA damage via fenton reaction-generated hydroxyl radicals during the recovery period. Appl Environ Microbiol 2007; 73:7740-3. [PMID: 17933934 DOI: 10.1128/aem.01079-07] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here, we show that resistance of Escherichia coli to TiO2 photocatalysis involves defenses against reactive oxygen species. Results support the idea that TiO2 photocatalysis generates damage which later becomes deleterious during recovery. We found this to be partly due to DNA attack via hydroxyl radicals generated by the Fenton reaction during recovery.
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Cuny C, Lesbats M, Dukan S. Induction of a global stress response during the first step of Escherichia coli plate growth. Appl Environ Microbiol 2006; 73:885-9. [PMID: 17142356 PMCID: PMC1800750 DOI: 10.1128/aem.01874-06] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have investigated the first events that occur when exponentially grown cells are transferred from a liquid medium (Luria-Bertani [LB]) to a solid medium (LB agar [LBA]). We observed an initial lag phase of 180 min for the wild type MG1655 without any apparent growth. This lack of growth was independent of the bacterial physiological state (either the stationary or the exponential phase), the solid medium composition, or the number of cells on the plate, but it was dependent on the bacterial genotype. Using lacZ-reporter fusions and two-dimensional electrophoresis analysis, we observed that when cells from exponential-phase cultures were plated on LBA, several global regulons, like heat shock regulons (RpoH, RpoE, CpxAR) and oxidative-stress regulons (SoxRS, OxyR, Fur), were immediately induced. Our results indicate that in order to grow on plates, bacteria must not only adapt to new conditions but also perceive a real stress.
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Affiliation(s)
- Caroline Cuny
- Laboratoire de Chimie Bactérienne, UPR 9043, CNRS, 31, Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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Abstract
Glutathione is one of the most abundant thiols present in cyanobacteria and proteobacteria, and in all mitochondria or chloroplast-bearing eukaryotes. In bacteria, in addition to its key role in maintaining the proper oxidation state of protein thiols, glutathione also serves a key function in protecting the cell from the action of low pH, chlorine compounds, and oxidative and osmotic stresses. Moreover, glutathione has emerged as a posttranslational regulator of protein function under conditions of oxidative stress, by the direct modification of proteins via glutathionylation. This review summarizes the biosynthesis and function of glutathione in bacteria from physiological and biotechnological standpoints.
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Affiliation(s)
- Lluis Masip
- Department of Chemical Engineering, Institute for Cell and Molecular Biology, University of Texas, Austin, 78712-0231, USA
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Maalej S, Dammak I, Dukan S. The impairment of superoxide dismutase coordinates the derepression of the PerR regulon in the response of Staphylococcus aureus to HOCl stress. Microbiology (Reading) 2006; 152:855-861. [PMID: 16514164 DOI: 10.1099/mic.0.28385-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The response ofStaphylococcus aureusto hypochlorous acid (HOCl) exposure was investigated. HOCl challenges were performed on cultures interrupted in the exponential phase. Pretreatment with HOCl conferred resistance to hydrogen peroxide in a PerR-dependent manner. Derepression of the PerR regulon was observed at low HOCl concentration (survival >50 %), using several fusions of different stress promoters tolacZreporter genes. At least four members of the PerR regulon (katA,mrgA,bcpandtrxA) encoding proteins with antioxidant properties were strongly induced following exposure to various HOCl concentrations. A striking result was the link between the derepression of the PerR regulon and the decreased superoxide dismutase (SOD) activity following exposure to increased HOCl concentrations. ThesodAmutant was more resistant than the wild-type and also had a higher level of 3-phosphoglycerate dehydrogenase (a measure of PerR regulon activity) without exposure to HOCl. Together, these results imply that derepression of PerR by HOCl is dependent on the level of SOD and protects exponentially arrested cells against HOCl stress.
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Affiliation(s)
- Sami Maalej
- Laboratoire de chimie bactérienne IBSM, CNRS UPR 9043, 31, chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
- Laboratoire de Microbiologie, Faculté des Sciences de Sfax, 3018 Sfax, Tunisia
| | - Ines Dammak
- Laboratoire de Microbiologie, Faculté des Sciences de Sfax, 3018 Sfax, Tunisia
| | - Sam Dukan
- Laboratoire de chimie bactérienne IBSM, CNRS UPR 9043, 31, chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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Sermon J, Wevers EMRP, Jansen L, De Spiegeleer P, Vanoirbeek K, Aertsen A, Michiels CW. CorA affects tolerance of Escherichia coli and Salmonella enterica serovar Typhimurium to the lactoperoxidase enzyme system but not to other forms of oxidative stress. Appl Environ Microbiol 2005; 71:6515-23. [PMID: 16269676 PMCID: PMC1287667 DOI: 10.1128/aem.71.11.6515-6523.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The enzyme lactoperoxidase is part of the innate immune system in vertebrates and owes its antimicrobial activity to the formation of oxidative reaction products from various substrates. In a previous study, we have reported that, with thiocyanate as a substrate, the lactoperoxidase system elicits a distinct stress response in Escherichia coli MG1655. This response is different from but partly overlapping with the stress responses to hydrogen peroxide and to superoxide. In the current work, we constructed knockouts in 10 lactoperoxidase system-inducible genes to investigate their role in the tolerance of E. coli MG1655 to this antimicrobial system. Five mutations resulted in a slightly increased sensitivity, but one mutation (corA) caused hypersensitivity to the lactoperoxidase system. This hypersensitive phenotype was specific to the lactoperoxidase system, since neither the sensitivity to hydrogen peroxide nor to the superoxide generator plumbagin was affected in the corA mutant. Salmonella enterica serovar Typhimurium corA had a similar phenotype. Although corA encodes an Mg2+ transporter and at least three other inducible open reading frames belonged to the Mg2+ regulon, repression of the Mg stimulon by Mg2+ did not change the lactoperoxidase sensitivity of either the wild-type or corA mutant. Prior exposure to 0.3 mM Ni2+, which is also transported by CorA, strongly sensitized MG1655 but not the corA mutant to the lactoperoxidase system. Furthermore, this Ni2+-dependent sensitization was suppressed by the CorA-specific inhibitor Co(III) hexaammine. These results indicate that CorA affects the lactoperoxidase sensitivity of E. coli by modulating the cytoplasmic concentrations of transition metals that enhance the toxicity of the lactoperoxidase system.
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Affiliation(s)
- Jan Sermon
- Katholieke Universiteit Leuven, Laboratory of Food Microbiology, Kasteelpark Arenberg 22, B-3001 Leuven, Belgium
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Aydin S. Antioxidant Status, α-Amylase Production, Growth, and Survival of Hemoglobin Bearing Escherichia coli Exposed to Hypochlorous Acid. BIOCHEMISTRY (MOSCOW) 2005; 70:1369-76. [PMID: 16417460 DOI: 10.1007/s10541-005-0271-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the present work, two matched strains of E. coli that bear a recombinant R-amylase gene (MK57) or the R-amylase gene and vgb (MK79-hemoglobin expressing strain) were exposed to HOCl. In these cells, glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), alpha-amylase production, growth and lethality were assessed in the presence and absence of HOCl. It was observed that the hemoglobin makes cells highly susceptible to killing by HOCl. The maximum survival for both strains was with stationary phase cells at any concentration of HOCl. Both strains grown in the presence of 0.0125-0.075 mg/liter HOCl showed a substantial increase in SOD activity and GSH level, with MK79 being the most increased strain in this respect, while the level of CAT activity was decreased in a dose depended manner. Growth of MK57 and MK79 strains decreased as HOCl concentration increased. However, HOCl at concentration above zero enhanced alpha-amylase production (about 2-fold) in both MK79 and MK57. Furthermore, total amylase production (at all HOCl concentrations) by MK79 was always greater than that by MK57. The results indicate that except for survival, the hemoglobin helps cells to grow better and produces more recombinant products and activates general defense systems more in response to oxidative stress when compared with the non-hemoglobin-containing counterpart.
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Affiliation(s)
- S Aydin
- Department of Biochemistry and Clinical Biochemistry, Firat University, Faculty of Medicine, Elazig, 23119, Turkey.
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Grandjean D, Fass S, Tozza D, Cavard J, Lahoussine V, Saby S, Guilloteau H, Block JC. Coliform culturability in over- versus undersaturated drinking waters. WATER RESEARCH 2005; 39:1878-86. [PMID: 15899286 DOI: 10.1016/j.watres.2005.03.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2004] [Revised: 02/25/2005] [Indexed: 05/02/2023]
Abstract
The culturability of Escherichia coli in undersaturated drinking water with respect to CaCO3 (corrosive water) or in oversaturated water (non-corrosive water) was tested in different reactors: glass flasks (batch, "non-reactive" wall); glass reactors (chemostat, "non-reactive" wall) versus a corroded cast iron Propella reactor (chemostat, "reactive" wall) and a 15-year-old distribution system pilot (chemostat, "reactive" wall with 1% corroded cast iron and 99% cement-lined cast iron). The E. coli in E. coli-spiked drinking water was not able to maintain its culturability and colonize the experimental systems. It appears from our results that the optimal pH for maintaining E. coli culturability was around 8.2 or higher. However, in reactors with a reactive wall (corroded cast iron), the decline in E. coli culturability was slower when the pH was adjusted to 7.9 or 7.7 (i.e. a reactor fed with corrosive water; pH<pHs) than in non-corrosive water (pH 8.64 or 8.24; pH>pHs). We tentatively deduce that corrosion products coming from chemical reactions driven by corrosive waters on the pipe wall improve E. coli culturability.
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Affiliation(s)
- D Grandjean
- LCPME, UMR 7564 CNRS-UHP, Faculté de Pharmacie, Pôle de l'Eau, 15 avenue du Charmois, 54500 Vandoeuvre-lès-Nancy, France
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Cuny C, Dukan L, Fraysse L, Ballesteros M, Dukan S. Investigation of the first events leading to loss of culturability during Escherichia coli starvation: future nonculturable bacteria form a subpopulation. J Bacteriol 2005; 187:2244-8. [PMID: 15774865 PMCID: PMC1065215 DOI: 10.1128/jb.187.7.2244-2248.2005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In previous experiments we were able to separate, using a nondestructive separation technique, culturable and nonculturable bacteria, from a Luria-Bertani (LB) medium culture of Escherichia coli incubated for 48 h. We observed in the nonculturable bacterial population an increase in oxidative damage and up-induction of most defenses against reactive oxygen species (ROS), along with a decrease in cytoplasmic superoxide dismutases. In this study, using the same separation technique, we separated into two subpopulations a 10-h LB medium culture containing only culturable bacteria. For the first time, we succeeded in associating physical separation with physiological differences. Although the levels of defense against ROS (RpoS, RpoH, OxyR, and SoxRS regulons) and oxidative damage (carbonyl contents) were apparently the same, we found that bacteria in one subpopulation were more sensitive to LB medium starvation and to various stresses, such as phosphate buffer starvation, heat shock, and hydrogen peroxide exposure. Based on these results, we suggest that these physiological differences reflect uncharacterized bacterial modifications which do not directly involve defenses against ROS.
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Affiliation(s)
- Caroline Cuny
- Laboratoire de Chimie Bactérienne-UPR 9043-CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille cedex 20, France
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Abid N, Maalej S, Rouis S. Morphological and physiological changes of Staphylococcus aureus exposed to hypochlorous acid. Lett Appl Microbiol 2004; 38:245-50. [PMID: 14962048 DOI: 10.1111/j.1472-765x.2004.01482.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
AIMS To characterize hypochlorous acid (HOCl) stress resistance of Staphylococcus aureus and to assess physiological state and changes in cell morphology. METHODS AND RESULTS Clinical wild-type strain of S. aureus was used in the stress with HOCl at concentrations ranging from 0 to 4 mg l(-1). Concentrations below 1.5 mg l(-1) caused no significant drop in viability. During 2 h of HOCl stress at 2 mg l(-1), there was appearance of minicells capable of passing through the 0.45 microm pores of filtration membranes. Intracellular proteins increased gradually to reach a level of 51% of dry weight and an enhanced synthesis of at least two proteins of 23 and 220 kDa was concluded. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY Staphylococcus aureus can undergo morphological and physiological changes during 2 h of exposure to 2 mg l(-1) of HOCl, which represents an adaptative response towards the hypochlorous acid stress. This evolution limits the use of 0.45 microm pores size membrane filters for research on S. aureus in waters and the clinical environment.
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Affiliation(s)
- N Abid
- Laboratoire de Microbiologie, Faculté des Sciences de Sfax, Sfax, Tunisia
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