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Gao Y, Peng D, Wang X, Lin S. Effects of the quorum sensing related luxS gene and lsr operon on Klebsiella michiganensis resisting copper stress. ENVIRONMENTAL RESEARCH 2024; 256:119244. [PMID: 38810822 DOI: 10.1016/j.envres.2024.119244] [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: 03/11/2024] [Revised: 05/21/2024] [Accepted: 05/26/2024] [Indexed: 05/31/2024]
Abstract
Industrial wastewater is a major environmental concern due to its high copper content, which poses significant toxicity to microbial life. Autoinducer-2 (AI-2) can participate in the inter- and intra-species communication and regulate the physiological functions of different bacterial species by producing AI-2 signal molecules. However, there are few research reports on the luxS gene and lsr operon functions for AI-2 in bacteria with a certain tolerance to copper. This study delves into the potential of quorum sensing mechanisms, particularly the AI-2 system, for enhancing microbial resistance to copper toxicity in Klebsiella michiganensis (KM). We detail the critical roles of the luxS gene in AI-2 synthesis and the lsr operon in AI-2 uptake, demonstrating their collective impact on enhancing copper resistance. Our findings show that mutations in the lsr operon, alongside the knockout of the luxS gene in KM strain (KMΔluxSΔlsr), significantly impair the strain's motility (p < 0.0001) and biofilm formation (p < 0.01), underscoring the operon's role in AI-2 transport. These genetic insights are pivotal for developing bioremediation strategies aimed at mitigating copper pollution in wastewater. By elucidating the mechanisms through which KM modulates copper resistance, this study highlights the broader ecological significance of leveraging microbial quorum sensing pathways for sustainable wastewater management.
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Affiliation(s)
- Ya Gao
- School of Environment, Northeast Normal University, Changchun, 130117, China
| | - Dongyu Peng
- School of Environment, Northeast Normal University, Changchun, 130117, China
| | - Xinlong Wang
- School of Environment, Northeast Normal University, Changchun, 130117, China
| | - Shanshan Lin
- School of Environment, Northeast Normal University, Changchun, 130117, China.
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Kang W, Zheng J, Bao J, Wang Z, Zheng Y, He JZ, Hu HW. Characterization of the copper resistance mechanism and bioremediation potential of an Acinetobacter calcoaceticus strain isolated from copper mine sludge. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:7922-7933. [PMID: 31893366 DOI: 10.1007/s11356-019-07303-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 12/04/2019] [Indexed: 06/10/2023]
Abstract
Bioremediation is one of the most effective ways for removal of heavy metals and restoration of contaminated sites. This study investigated the copper (Cu) resistance mechanism and bioremediation potential of an Acinetobacter calcoaceticus strain KW3 isolated from sludge of Cu mine. The effect of Cu concentrations on the bacterial growth, biomass, and adsorption capacity, as well as the effect of contact time on the adsorption process was evaluated in a batch biosorption test. The strain exhibited strong tolerance of Cu, and the minimal inhibitory concentration was around 400 mg Cu2+ L-1, at which the maximum adsorption capacity was 14.1 mg g-1 dry cell mass. Cell walls and intracellular soluble components adsorbed 51.2% and 46.6% of Cu2+, respectively, suggesting that the strain not only adsorbed Cu2+ on the surface but also metastasized ions into cells. The adsorption and kinetic data were well fitted with Freundlich isotherm and Pseudo-second-order models, suggesting that cell surface had a high affinity for Cu2+ and the chemisorption could be the main adsorption mechanism. Scanning electron microscope and Fourier transform infrared spectroscopy analysis revealed that hydroxyl, carboxylic, amide, sulfate, and phosphate on cell walls might be involved in the biosorption process. Two-dimensional gel electrophoresis and MALDI-TOF/TOF mass spectrometry revealed that some oxidoreductases, in particular Cu resistance protein A (CopA) expression levels, were upregulated. Antioxidant defense and P1B-type ATPases CopA efflux might play a crucial role in maintaining cellular homeostasis and intracellular detoxification. To our knowledge, this is the first time that Cu resistance mechanisms, especially intracellular enzymatic mechanisms, were identified in an A. calcoaceticus KW3 strain.
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Affiliation(s)
- Wei Kang
- School of Environmental Science and Engineering, Hubei Key Laboratory of Mine Environmental Pollution Control and Remediation, Hubei Polytechnic University, Huangshi, 435003, China
- Hubei Provincial Key Laboratory of Mining Area Environmental Pollution Control and Remediation, Hubei Polytechnic University, Huangshi, 435003, China
| | - Jin Zheng
- Hubei Provincial Key Laboratory of Mining Area Environmental Pollution Control and Remediation, Hubei Polytechnic University, Huangshi, 435003, China
| | - Jianguo Bao
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430070, China
| | - Zhen Wang
- Hubei Provincial Key Laboratory of Mining Area Environmental Pollution Control and Remediation, Hubei Polytechnic University, Huangshi, 435003, China
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430070, China
| | - Yong Zheng
- Key Laboratory for Humid Subtropical Eco-geographical Processes of the Ministry of Education, Fujian Normal University, Fuzhou, 350007, China
| | - Ji-Zheng He
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Hang-Wei Hu
- Key Laboratory for Humid Subtropical Eco-geographical Processes of the Ministry of Education, Fujian Normal University, Fuzhou, 350007, China.
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia.
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Thummeepak R, Pooalai R, Harrison C, Gannon L, Thanwisai A, Chantratita N, Millard AD, Sitthisak S. Essential Gene Clusters Involved in Copper Tolerance Identified in Acinetobacter baumannii Clinical and Environmental Isolates. Pathogens 2020; 9:pathogens9010060. [PMID: 31952222 PMCID: PMC7169445 DOI: 10.3390/pathogens9010060] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 01/10/2020] [Accepted: 01/13/2020] [Indexed: 12/13/2022] Open
Abstract
Copper is widely used as antimicrobial in agriculture and medicine. Copper tolerance mechanisms of pathogenic bacteria have been proven to be required for both copper tolerance and survival during bacterial infections. Here, we determined both copper-tolerant phenotype and genotype in A. baumannii originated from clinical and environmental samples. Using copper susceptibility testing, copper-tolerant A. baumannii could be found in both clinical and environmental isolates. Genotypic study revealed that representative copper-related genes of the cluster A (cueR), B (pcoAB), and D (oprC) were detected in all isolates, while copRS of cluster C was detected in only copper-tolerant A. baumannii isolates. Moreover, we found that copper-tolerant phenotype was associated with amikacin resistance, while the presence of copRS was statistically associated with blaNDM-1. We chose the A. baumannii strain AB003 as a representative of copper-tolerant isolate to characterize the effect of copper treatment on external morphology as well as on genes responsible for copper tolerance. The morphological features and survival of A. baumannii AB003 were affected by its exposure to copper, while whole-genome sequencing and analysis showed that it carried fourteen copper-related genes located on four clusters, and cluster C of AB003 was found to be embedded on genomic island G08. Transcriptional analysis of fourteen copper-related genes identified in AB003 revealed that copper treatment induced the expressions of genes of clusters A, B, and D at the micromolar level, while genes of cluster C were over-expressed at the millimolar levels of copper. This study showed that both clinical and environmental A. baumannii isolates have the ability to tolerate copper and carried numerous copper tolerance determinants including intrinsic copper tolerance (clusters A, B, and D) and acquired copper tolerance (cluster C) that could respond to copper toxicity. Our evidence suggests that we need to reconsider the use of copper in hospitals and other medical environments to prevent the selection and spread of copper-tolerant organisms.
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Affiliation(s)
- Rapee Thummeepak
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand; (R.T.); (R.P.); (A.T.)
| | - Renuka Pooalai
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand; (R.T.); (R.P.); (A.T.)
| | - Christian Harrison
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK; (C.H.); (L.G.); (A.D.M.)
| | - Lucy Gannon
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK; (C.H.); (L.G.); (A.D.M.)
| | - Aunchalee Thanwisai
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand; (R.T.); (R.P.); (A.T.)
| | - Narisara Chantratita
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand;
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Andrew D. Millard
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK; (C.H.); (L.G.); (A.D.M.)
| | - Sutthirat Sitthisak
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand; (R.T.); (R.P.); (A.T.)
- Correspondence: ; Tel.: +66-55-964626; Fax: +66-55-964770
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Padmavathi AR, Sriyutha Murthy P, Das A, Nishad PA, Pandian R, Rao TS. Copper oxide nanoparticles as an effective anti-biofilm agent against a copper tolerant marine bacterium, Staphylococcus lentus. BIOFOULING 2019; 35:1007-1025. [PMID: 31718302 DOI: 10.1080/08927014.2019.1687689] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 10/21/2019] [Accepted: 10/26/2019] [Indexed: 06/10/2023]
Abstract
Biofilm formation on antifouling coatings is a serious concern in seawater cooling systems and the maritime industry. A prolific biofilm forming strain (Staphylococcus lentus), possessing high tolerance (>1,000 µg ml-1) to dissolved copper ions (Cu++) was isolated from titanium coupons exposed in the coastal waters of Kalpakkam, east coast of India. S. lentus formed increased biofilm (p < 0.05) at 100 µg ml-1 of Cu++ ions, when compared with the untreated control. To combat biofilm formation of this strain, the efficacy of copper oxide nanoparticles synthesized from copper nitrate by varying the concentrations of hexamine and cetyl trimethyl ammonium bromide (CTAB), was investigated. Complete (100%) inhibition of biofilm formation was observed with plain CuO NP (0.5 M hexamine, uncapped) at 1,000 µg ml-1. Capping with CTAB, influenced the morphology and the purity of the synthesized CuO NPs but did not alter their surface charge. Capping reduced metal ion release from CuO NPs and their antibacterial and anti-biofilm property against S. lentus. Overall, uncapped CuO NPs were effective in controlling biofilm formation of S. lentus. Concurrent release of copper ions and contact mediated physical damage by CuO NPs offer a promising approach to tackle metal tolerant biofilm bacteria.
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Affiliation(s)
- Alwar Ramanujam Padmavathi
- Water and Steam Chemistry Division, Bhabha Atomic Research Centre Facilities, Kalpakkam, Tamil Nadu, India
| | - P Sriyutha Murthy
- Water and Steam Chemistry Division, Bhabha Atomic Research Centre Facilities, Kalpakkam, Tamil Nadu, India
- Life Sciences Department, Homi Bhabha National Institute, Mumbai, India
| | - Arindam Das
- Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu, India
- Chemical Sciences Department, Homi Bhabha National Institute, Mumbai, India
| | - Padala Abdul Nishad
- Water and Steam Chemistry Division, Bhabha Atomic Research Centre Facilities, Kalpakkam, Tamil Nadu, India
| | - Ramanathasamy Pandian
- Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu, India
| | - Toleti Subba Rao
- Water and Steam Chemistry Division, Bhabha Atomic Research Centre Facilities, Kalpakkam, Tamil Nadu, India
- Life Sciences Department, Homi Bhabha National Institute, Mumbai, India
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Copper Resistance of the Emerging Pathogen Acinetobacter baumannii. Appl Environ Microbiol 2016; 82:6174-6188. [PMID: 27520808 DOI: 10.1128/aem.01813-16] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 08/04/2016] [Indexed: 11/20/2022] Open
Abstract
Acinetobacter baumannii is an important emerging pathogen that is capable of causing many types of severe infection, especially in immunocompromised hosts. Since A. baumannii can rapidly acquire antibiotic resistance genes, many infections are on the verge of being untreatable, and novel therapies are desperately needed. To investigate the potential utility of copper-based antibacterial strategies against Acinetobacter infections, we characterized copper resistance in a panel of recent clinical A. baumannii isolates. Exposure to increasing concentrations of copper in liquid culture and on solid surfaces resulted in dose-dependent and strain-dependent effects; levels of copper resistance varied broadly across isolates, possibly resulting from identified genotypic variation among strains. Examination of the growth-phase-dependent effect of copper on A. baumannii revealed that resistance to copper increased dramatically in stationary phase. Moreover, A. baumannii biofilms were more resistant to copper than planktonic cells but were still susceptible to copper toxicity. Exposure of bacteria to subinhibitory concentrations of copper allowed them to better adapt to and grow in high concentrations of copper; this copper tolerance response is likely achieved via increased expression of copper resistance mechanisms. Indeed, genomic analysis revealed numerous putative copper resistance proteins that share amino acid homology to known proteins in Escherichia coli and Pseudomonas aeruginosa Transcriptional analysis revealed significant upregulation of these putative copper resistance genes following brief copper exposure. Future characterization of copper resistance mechanisms may aid in the search for novel antibiotics against Acinetobacter and other highly antibiotic-resistant pathogens. IMPORTANCE Acinetobacter baumannii causes many types of severe nosocomial infections; unfortunately, some isolates have acquired resistance to almost every available antibiotic, and treatment options are incredibly limited. Copper is an essential nutrient but becomes toxic at high concentrations. The inherent antimicrobial properties of copper give it potential for use in novel therapeutics against drug-resistant pathogens. We show that A. baumannii clinical isolates are sensitive to copper in vitro, both in liquid and on solid metal surfaces. Since bacterial resistance to copper is mediated though mechanisms of efflux and detoxification, we identified genes encoding putative copper-related proteins in A. baumannii and showed that expression of some of these genes is regulated by the copper concentration. We propose that the antimicrobial effects of copper may be beneficial in the development of future therapeutics that target multidrug-resistant bacteria.
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