Degradation and deactivation of plasmid-encoded antibiotic resistance genes during exposure to ozone and chlorine.

Autor: Yoon Y; School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea., He H; Department of Civil and Environmental Engineering, University of Washington, Seattle, WA 98195, United States., Dodd MC; Department of Civil and Environmental Engineering, University of Washington, Seattle, WA 98195, United States. Electronic address: doddm@uw.edu., Lee Y; School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea. Electronic address: yhlee42@gist.ac.kr.
Jazyk: angličtina
Zdroj: Water research [Water Res] 2021 Sep 01; Vol. 202, pp. 117408. Date of Electronic Publication: 2021 Jul 06.
DOI: 10.1016/j.watres.2021.117408
Abstrakt: Degradation and deactivation kinetics of an antibiotic resistance gene (ARG) by ozone (O 3 ) and free available chlorine (FAC) were investigated in phosphate-buffered solutions at pH 7 for O 3 (in the presence of tert‑butanol), and pH 6.8 or 8.1 for FAC. We used a plasmid (pUC19)-encoded ampicillin resistance gene (amp R ) in both extracellular (e-) and intracellular (i-) forms. The second-order rate constant (k O3 ) for degradation of 2686 base pair (bp) long e-pUC19 toward O 3 , which was determined by quantitative polymerase chain reaction assay, was calculated to be ~2 × 10 5 M - 1 s -1 . The deactivation rate constants of e-pUC19 by O 3 measured with various recipient E. coli strains were within a factor of 2 compared with the degradation rate constant for e-pUC19. The degradation/deactivation kinetics of i-pUC19 were similar to those of e-pUC19, indicating only a minor influence of cellular components on O 3 reactivity toward i-pUC19. For FAC, the degradation and deactivation rates of e-pUC19 were decreased in the presence of tert‑butanol, implying involvement of direct FAC as well as some radical (e.g., • OH) reactions. The degradation rates of e-amp R segments by direct FAC reaction could be explained by a previously-reported two-step sequential reaction model, in which the rate constants increased linearly with e-amp R segment length. The deactivation rate constants of e-pUC19 during exposure to FAC were variable by a factor of up to 4.3 for the different recipient strains, revealing the role of DNA repair in the observed deactivation efficiencies. The degradation/deactivation of e-pUC19 were significantly faster at pH 6.8 than at pH 8.1 owing to pH-dependent FAC speciation variation, whereas i-pUC19 kinetics exhibited much smaller dependence on pH, demonstrating intracellular plasmid DNA reactions with FAC occurred at cytoplasmic pH (~7.5). Our results are useful for predicting and/or measuring the degradation/deactivation efficiency of plasmid-encoded ARGs by water treatment with ozonation and chlorination.
(Copyright © 2021. Published by Elsevier Ltd.)
Databáze: MEDLINE
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