1. Amperometric detection of Enterobacteriaceae in river water by measuring β-galactosidase activity at interdigitated microelectrode arrays.
- Author
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Laczka O, García-Aljaro C, del Campo FJ, Muñoz Pascual FX, Mas-Gordi J, and Baldrich E
- Subjects
- Aminophenols analysis, Aminophenols chemistry, Electrochemistry, Enterobacteriaceae enzymology, Glucosides metabolism, Limit of Detection, Microelectrodes, Oxidation-Reduction, Time Factors, Water Supply standards, beta-Galactosidase metabolism, Biosensing Techniques methods, Enterobacteriaceae isolation & purification, Rivers chemistry, Water Microbiology, Water Supply analysis, beta-Galactosidase analysis
- 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 6×10(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., (Copyright © 2010 Elsevier B.V. All rights reserved.)
- Published
- 2010
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