Exploring the Role of Coliform Bacteria in Class 1 Integron Carriage and Biofilm Formation During Drinking Water Treatment

Microb Ecol. 2016 Nov;72(4):773-782. doi: 10.1007/s00248-016-0758-0. Epub 2016 Apr 14.

Abstract

This study investigates the role of coliforms in the carriage of class 1 integron and biocide resistance genes in a drinking water treatment plant and explores the relationship between the carriage of such genes and the biofouling abilities of the strain. The high incidence of class 1 integron and biocide resistance genes (33.3 % of the isolates) highlights the inherent risk of genetic contamination posed by coliform populations during drinking water treatment. The association between the presence of intI1 gene and qac gene cassettes, especially qacH, was greater in biofilm cells. In coliforms recovered from biofilms, a higher frequency of class 1 integron elements and higher diversity of genetic patterns occurred, compared to planktonic cells. The coliform isolates under the study proved to mostly carry non-classical class 1 integrons lacking the typical qacEΔ1/sul1 genes or a complete tni module, but bearing the qacH gene. No link was found between the carriage of integron genes and the biofouling degree of the strain, neither in aerobic or in anaerobic conditions. Coliform bacteria isolated from established biofilms rather adhere in oxygen depleted environments, while the colonization ability of planktonic cells is not significantly affected by oxygen availability.

Keywords: Biofilm assay; Class 1 integron; Planktonic versus biofilm phenotype; qac genes.

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Base Sequence
  • Biofilms / growth & development*
  • DNA, Bacterial / genetics
  • Disinfectants / pharmacology*
  • Drinking Water / chemistry
  • Drinking Water / microbiology*
  • Drug Resistance, Bacterial / genetics*
  • Enterobacteriaceae / drug effects*
  • Enterobacteriaceae / genetics*
  • Enterobacteriaceae / isolation & purification
  • Integrases / genetics
  • Membrane Transport Proteins / genetics
  • RNA, Ribosomal, 16S / genetics
  • Sequence Analysis, DNA
  • Water Microbiology
  • Water Purification / methods*

Substances

  • Anti-Bacterial Agents
  • DNA, Bacterial
  • Disinfectants
  • Drinking Water
  • Membrane Transport Proteins
  • RNA, Ribosomal, 16S
  • Integrases
  • integron integrase IntI1