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

• Published in: Analytica chimica acta 2010-09, Vol.677 (2), p.156-161
• Main Authors: Laczka, Olivier, García-Aljaro, Cristina, del Campo, Francisco Javier, Pascual, Francesc Xavier Muñoz, Mas-Gordi, Jordi, Baldrich, Eva
• Format: Article
• Language: English
• Subjects: Aminophenols - analysis; Aminophenols - chemistry; Analysis methods; Analytical chemistry; Applied sciences; beta-Galactosidase - analysis; beta-Galactosidase - metabolism; Biosensing Techniques - methods; Chemistry; Coliform detection; Electrochemical methods; Electrochemistry; Enterobacteriaceae - enzymology; Enterobacteriaceae - isolation & purification; Exact sciences and technology; Glucosides - metabolism; Interdigitated microlectrode array; Limit of Detection; Microelectrodes; Natural water pollution; Oxidation-Reduction; Pollution; Redox cycling; River water; Rivers - chemistry; Time Factors; Water Microbiology; Water Supply - analysis; Water Supply - standards; Water treatment and pollution; β-Galactosidase
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2010.08.001

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 × 10 5 CFU mL −1 Escherichia coli in 2 h 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 × 10 4 CFU mL −1 E. coli could be detected after 2 h of incubation, while 7 h of incubation were enough to detect down to 10 CFU mL −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.