Change in hydrophilicity of penicillins during advanced oxidation by radiolytically generated .OH compromises the elimination of selective pressure on bacterial strains

László Szabó, Tünde Tóth, Tekla Engelhardt, Gergely Rácz, Csilla Mohácsi-Farkas, E. Takács, L. Wojnárovits

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Advanced oxidation processes are promising technologies for removal of antibiotic residues from wastewater in terms of their high efficacy. However, recent studies have reported the remaining antibacterial activity of the products at early-stages of treatment. The present study investigates the effect of such products of model β-lactams (amoxicillin, ampicillin, cloxacillin) on bacteria introducing structure-based, and biological approaches involving Gram-positive and Gram-negative bacterial strains. Chemical analysis revealed the destruction of the β-lactam pharmacophore in competition with the reaction at the aromatic ring. Multisite attack occurs on the penicillin skeleton producing OH-substituted products. The enhanced hydrophilicity confers higher diffusion rate through the porin channels of Gram-negative bacteria and through the hydrophilic cell wall of Gram-positive species. Accordingly, an increase in acute toxicity of treated samples was observed at the beginning of the treatment. The same tendency was observed for target-specific antimicrobial activity investigated with antibiotic susceptibility testing (agar-diffusion, bacterial growth). Prolonged treatments yielded products, e.g. polyhydroxylated phenolic compounds, being also deleterious for bacteria. Therefore, the advanced oxidation process should be judiciously optimized.

Original languageEnglish
Pages (from-to)393-403
Number of pages11
JournalScience of the Total Environment
Volume551-552
DOIs
Publication statusPublished - May 1 2016

Keywords

  • Advanced oxidation
  • Antibiotic resistance
  • Bacterial susceptibility
  • Bacterial toxicity
  • Hydroxyl radical
  • Penicillin

ASJC Scopus subject areas

  • Environmental Chemistry
  • Pollution
  • Waste Management and Disposal
  • Environmental Engineering

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