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Creamer KE, Ditmars FS, Basting PJ, Kunka KS, Hamdallah IN, Bush SP, Scott Z, He A, Penix SR, Gonzales AS, Eder EK, Camperchioli DW, Berndt A, Clark MW, Rouhier KA, Slonczewski JL. Benzoate- and Salicylate-Tolerant Strains of Escherichia coli K-12 Lose Antibiotic Resistance during Laboratory Evolution. Appl Environ Microbiol 2017; 83:e02736-16. [PMID: 27793830 PMCID: PMC5203621 DOI: 10.1128/aem.02736-16] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 10/24/2016] [Indexed: 01/10/2023] Open
Abstract
Escherichia coli K-12 W3110 grows in the presence of membrane-permeant organic acids that can depress cytoplasmic pH and accumulate in the cytoplasm. We conducted experimental evolution by daily diluting cultures in increasing concentrations of benzoic acid (up to 20 mM) buffered at external pH 6.5, a pH at which permeant acids concentrate in the cytoplasm. By 2,000 generations, clones isolated from evolving populations showed increasing tolerance to benzoate but were sensitive to chloramphenicol and tetracycline. Sixteen clones grew to stationary phase in 20 mM benzoate, whereas the ancestral strain W3110 peaked and declined. Similar growth occurred in 10 mM salicylate. Benzoate-evolved strains grew like W3110 in the absence of benzoate, in media buffered at pH 4.8, pH 7.0, or pH 9.0, or in 20 mM acetate or sorbate at pH 6.5. Genomes of 16 strains revealed over 100 mutations, including single-nucleotide polymorphisms (SNPs), large deletions, and insertion knockouts. Most strains acquired deletions in the benzoate-induced multiple antibiotic resistance (Mar) regulon or in associated regulators such as rob and cpxA, as well as the multidrug resistance (MDR) efflux pumps emrA, emrY, and mdtA Strains also lost or downregulated the Gad acid fitness regulon. In 5 mM benzoate or in 2 mM salicylate (2-hydroxybenzoate), most strains showed increased sensitivity to the antibiotics chloramphenicol and tetracycline; some strains were more sensitive than a marA knockout strain. Thus, our benzoate-evolved strains may reveal additional unknown drug resistance components. Benzoate or salicylate selection pressure may cause general loss of MDR genes and regulators. IMPORTANCE Benzoate is a common food preservative, and salicylate is the primary active metabolite of aspirin. In the gut microbiome, genetic adaptation to salicylate may involve loss or downregulation of inducible multidrug resistance systems. This discovery implies that aspirin therapy may modulate the human gut microbiome to favor salicylate tolerance at the expense of drug resistance. Similar aspirin-associated loss of drug resistance might occur in bacterial pathogens found in arterial plaques.
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Affiliation(s)
| | | | | | - Karina S Kunka
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | | | - Sean P Bush
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | - Zachary Scott
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | - Amanda He
- Department of Biology, Kenyon College, Gambier, Ohio, USA
| | | | | | | | | | - Adama Berndt
- Department of Biology, Kenyon College, Gambier, Ohio, USA
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Jacobs L, Emmerechts J, Mathieu C, Hoylaerts MF, Fierens F, Hoet PH, Nemery B, Nawrot TS. Air pollution related prothrombotic changes in persons with diabetes. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:191-6. [PMID: 20123602 PMCID: PMC2831916 DOI: 10.1289/ehp.0900942] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 10/22/2009] [Indexed: 05/03/2023]
Abstract
BACKGROUND Population studies suggest that persons with diabetes are more sensitive to the effects of particulate matter (PM) air pollution. However, the biological mechanisms of a possible prothrombotic effect underlying this enhanced susceptibility remain largely unknown. OBJECTIVE We hypothesized that exposure to PM causes prothrombotic changes in persons with diabetes, possibly via systemic inflammation. METHODS Our study included 137 nonsmoking adults with diabetes who were outpatients at the University Hospital Leuven. Recent exposure (2 hr before examination) to ambient PM was measured at the entrance of the hospital. Individual chronic exposure to PM was assessed by measuring the area occupied by carbon in airway macrophages obtained by sputum induction. Platelet function was measured ex vivo with the PFA-100 platelet function analyzer, which simulates a damaged blood vessel; we analyzed the function of platelets in primary hemostasis under high shear conditions. Total and differential blood leukocytes were counted. RESULTS Independent of antiplatelet medication, an interquartile range (IQR) increase of 39.2 microg/m3 in PM10 (PM with aerodynamic diameter <or= 10 microm) concentration measured 2 hr before the clinical examination (recent exposure) was associated with a decrease of 21.1 sec [95% confidence interval (CI), 35.3 to 6.8] in the PFA-100 closure time (i.e., increased platelet activation) and an increase in blood leukocytes of 512 per microliter of blood (95% CI, 45.2979). Each area increase of 0.25 microm2 (IQR) in carbon load of airway macrophages (chronic exposure) was associated with an increase of 687 leukocytes per microliter of blood (95% CI, 2241,150). CONCLUSIONS A relevant increase in recent PM exposure was associated with a change in platelet function toward a greater prothrombotic tendency. The magnitude of the change was about two-thirds (in the opposite direction) of the average effect of antiplatelet medication. Diabetic patients showed evidence of proinflammatory response to both recent and chronic exposure to PM air pollution.
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Affiliation(s)
- Lotte Jacobs
- Occupational and Environmental Medicine, Unit of Lung Toxicology
| | | | - Chantal Mathieu
- Department of Endocrinology, Katholique Universiteit Leuven, Leuven, Belgium
| | | | - Frans Fierens
- Belgian interregional Environment Agency, Brussels, Belgium
| | - Peter H. Hoet
- Occupational and Environmental Medicine, Unit of Lung Toxicology
| | - Benoit Nemery
- Occupational and Environmental Medicine, Unit of Lung Toxicology
- Address correspondence to B. Nemery, K.U. Leuven, Occupational and Environmental Medicine and Pneumology, Unit of Lung Toxicology, Herestraat 49 (O&N 706), B-3000 Leuven, Belgium. Telephone: 32-16-347121. Fax: 32-16-347124. E-mail:
| | - Tim S. Nawrot
- Occupational and Environmental Medicine, Unit of Lung Toxicology
- Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium
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