Disappearance of oxytetracycline resistance genes in aquatic systems

Christina A. Engemann, Laura Adams, Charles W. Knapp, David W. Graham

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

The disappearance of selected tetracycline resistance genes was investigated in different simulated receiving waters to determine conditions that maximize resistance gene loss after release. Wastewater from an operating cattle feedlot lagoon was provided to four pairs of duplicate 3-L flasks, and tet(O), tet(W), tet(M), tet(Q), and 16S rRNA gene levels were monitored over 29 days using realtime PCR. Treatments included simulated sunlight with 0, 25, and 250 mu g L-1 nominal oxytetracycline (OTC) levels, respectively, and 'dark' conditions. Gene disappearance rates were always highest when light was present, regardless of OTC level. First-order loss coefficients (k(d)) for the sum of resistance genes were 0.84, 0.75, and 0.81 day(-1) for 0.0, 25, and 250 mu g L-1 OTC treatments over the first 7 days after release, respectively, whereas kd was 0.49 day l under dark conditions, which is significantly lower (P < 0.10). k(d) varied fourfold among the four individual genes, although disappearance patterns were similar among genes. Results suggest that light exposure should be maximized in receiving waters in order to maximize resistance gene loss rate after release.
Original languageEnglish
Pages (from-to)176-182
Number of pages6
JournalFEMS Microbiology Letters
Volume263
Issue number2
DOIs
Publication statusPublished - Oct 2006

Keywords

  • antibiotic resistance
  • oxytetracycline
  • real-time PCR
  • gene
  • disappearance kinetics
  • aquatic systems

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