Determination and quantification of Escherichia coli by capillary electrophoresis

Abstract

Capillary electrophoresis (CE) is widely employed for the separation of nucleic acids or protein, but it is rarely applied in the quantification of Escherichia coli (E. coli). Here, we have analysed E. coli by CE with mercury lamp induced fluorescence, and demonstrated the relationship between its fluorescence intensity with the concentration of E. coli for the first time. The gradient concentration of E. coli was obtained by polymerase chain reaction (PCR) with different amplification cycles and dilution certain PCR products of E. coli, respectively. Results show that the peak area was linearly related to the logarithm of the concentration of E. coli and the logarithm of PCR replication numbers. The correlation coefficients R² are 0.957 and 0.966, respectively. The limit of detection (LOD) was found to be about 8.913 × 10⁻¹⁵ mol μl⁻¹. The reproducibility of capillary electrophoresis may make this technique possible for quantitative measurement of bacteria in bio-analytical science.