Amperometric detection of Enterobacteriaceae in river water by measuring β-galactosidase activity at interdigitated microelectrode arrays

Olivier Laczka, Cristina García-Aljaro, Francisco Javier del Campo, Francesc Xavier Muñoz Pascual, Jordi Mas-Gordi, Eva Baldrich

Research output: Contribution to journalArticleResearchpeer-review

36 Citations (Scopus)

Abstract

Two simple methodologies are compared for the detection of faecal contamination in water using amperometry at gold interdigitated microelectrodes. They rely on the detection of β-galactosidase (β-gal) by redox cycling amperometry of the p-aminophenol (PAP) produced by the enzyme from the 4-aminophenyl β-d-galactopyranoside (PAPG) substrate. The use of phages as specific agents for the release of the bacteria-enclosed enzyme allowed the detection of 6×105CFUmL-1 Escherichia coli in 2h without any pre-enrichment or preconcentration steps. Better limits of detection were achieved for the second strategy in the absence of phages. In this case, bacteria were enriched in the presence of both β-d-1-thiogalactopyranoside (IPTG) and substrate but in the absence of phages. Under such experimental conditions, 5×104CFUmL-1 E. coli could be detected after 2h of incubation, while 7h of incubation were enough to detect down to 10CFUmL-1 in river water samples. This represents a straightforward one-step method for the detection of faecal contamination that can be conducted in a single working day with minimal sample manipulation by the user. © 2010 Elsevier B.V.
Original languageEnglish
Pages (from-to)156-161
JournalAnalytica Chimica Acta
Volume677
DOIs
Publication statusPublished - 1 Sep 2010

Keywords

  • Coliform detection
  • Electrochemistry
  • Interdigitated microlectrode array
  • Redox cycling
  • River water
  • β-Galactosidase

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