Author ORCID Identifier

https://orcid.org/0000-0001-8497-5945

Document Type

Article

Publication Title

Environmental Science & Technology

Abstract

This work investigated degradation (measured by qPCR) and biological deactivation (measured by culture-based natural transformation) of extra- and intracellular antibiotic resistance genes (eARGs and iARGs) by free available chlorine (FAC), NH2Cl, O3, ClO2, and UV light (254 nm), and of eARGs by •OH, using a chromosomal ARG (blt) of multidrug-resistant Bacillus subtilis 1A189. Rate constants for degradation of four 266–1017 bp amplicons adjacent to or encompassing the acfA mutation enabling blt overexpression increased in proportion to #AT+GC bps/amplicon, or in proportion to #5′-GG-3′ or 5′-TT-3′ doublets/amplicon, with respective values ranging from 0.59 to 2.3 (×1011 M–1 s–1) for •OH, 1.8–6.9 (×104 M–1 s–1) for O3, 3.9–9.2 (×103 M–1 s–1) for FAC, 0.35–1.2(×101 M–1 s–1) for ClO2, and 2.0–8.8 (×10–2 cm2/mJ) for UV at pH 7, and from 1.7–4.4 M–1 s–1 for NH2Cl at pH 8. For FAC, NH2Cl, O3, ClO2, and UV, ARG deactivation paralleled degradation of amplicons approximating a ∼800–1000 bp acfA-flanking sequence required for natural transformation in B. subtilis, whereas deactivation outpaced degradation for •OH. At practical disinfectant exposures, eARGs and iARGs were ≥90% degraded/deactivated by FAC, O3, and UV, but recalcitrant to NH2Cl and ClO2. iARG degradation/deactivation always lagged cell inactivation. These findings provide a quantitative framework for evaluating ARG fate during disinfection/oxidation, and support using qPCR as a proxy for tracking ARG deactivation under carefully selected circumstances.

Pages

2013-2016

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DOI

https://doi.org/10.1021/acs.est.8b04393

Volume

53

Issue

4

Publication Date

2019

Disciplines

Civil and Environmental Engineering

Comments

This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.

This item is included in the Center for Climate, Society, & the Environment's Faculty Publications Bibliography.

Find more Climate Studies works by Gonzaga University faculty at the bibliography's home here.

ISSN

0013-936X

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