Quantitation of bacteria through adsorption of intracellular biomolecules on carbon paste and screen-printed carbon electrodes and voltammetry of redox-active probes |
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Authors: | Agnes Obuchowska |
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Institution: | (1) Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1 |
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Abstract: | A new electrochemical method for the quantitation of bacteria that is rapid, inexpensive, and amenable to miniaturization
is reported. Cyclic voltammetry was used to quantitate M. luteus, C. sporogenes, and E. coli JM105 in exponential and stationary phases, following exposure of screen-printed carbon working electrodes (SPCEs) to lysed
culture samples. Ferricyanide was used as a probe. The detection limits (3s) were calculated and the dynamic ranges for E. coli (exponential and stationary phases), M. luteus (exponential and stationary phases), and C. sporogenes (exponential phase) lysed by lysozyme were 3 × 104 to 5 × 106 colony-forming units (CFU) mL−1, 5 × 106 to 2 × 108 CFU mL−1 and 3 × 103 to 3 × 105 CFU mL−1, respectively. Good overlap was obtained between the calibration curves when the electrochemical signal was plotted against
the dry bacterial weight, or between the protein concentration in the bacterial lysate. In contrast, unlysed bacteria did
not change the electrochemical signal of ferricyanide. The results indicate that the reduction of the electrochemical signal
in the presence of the lysate is mainly due to the fouling of the electrode by proteins. Similar results were obtained with
carbon-paste electrodes although detection limits were better with SPCEs. The method described herein was applied to quantitation
of bacteria in a cooling tower water sample.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Quantitation of bacteria Lysis Screen-printed carbon electrode Voltammetry Adsorption Biomolecules |
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