Determination of the bacterial pathogen Edwardsiella tarda in fish species by capillary electrophoresis with blue light-emitting diode-induced fluorescence

Abstract

High-performance capillary electrophoresis (HPCE) has been applied to the identification, separation, and quantitation of intact bacteria. We demonstrate that a pathogen (Edwardsiella tarda) which causes systemic infection in commercially important fish species can be rapidly identified and determined ( 1 200 000 theoretical plates/m) was achieved with this rapid and efficient CE method. It was found that proper sample vortexing (90 s) would be beneficial to disperse aggregated cells and facilitate the focusing of intact cells during electrophoresis. Ionization of the surface constituents of Edwardsiella tarda cells provided efficient surface charges for the intact cells to be separated from the EOF and damaged or lysed cells when the separation was performed in running buffer (3.94 mM Tris, 0.56 mM borate, 0.013 mM EDTA) at pH 10.5. The limit of detection (LOD) and recovery were found to be 4.2 × 104 cells/mL and 70.0%, respectively. This proposed CE method could become an effective tool for diagnosis and tracking of certain diseases caused by bacteria in fish species as well as in human beings. © 2004 Wiley-VCH Verlag GmbH & Co. KGaA.