[Ion-exchange chromatographic behavior and characterization of Staphylococcus aureus in exponential phase]

A rapid, simple and sensitive method was developed to characterize S. aureus in exponential phase by a high performance ion-exchange chromatograph equipped with a laser light-scattering detector. An ion-exchange column (TSKgel SuperQ-TOYOPEARL 650C column, 7.6 mm i.d. x 100 mm, Tosoh, Japan) was used for the separation. The mobile phase was a 20 mmol/L piperazine-hydrochloric acid (pH 6.0) buffer. It was found that S. aureus in exponential phase exhibited two elution peaks. Transmission electron microscope (TEM) showed that the bacterial cells in the first peak appeared to be circular, while the cells in the second one appeared to be elliptical and had one obvious diaphragm. It is found that the proliferation capability of the second fraction was better than the first fraction by 65.3%. These results suggested that the first fraction was the S. aureus that stopped dividing, while the second one was the S. aureus that were undergoing cell division. Therefore, the chromatographic method developed here may be a promising tool for the rapid and efficient separation and characterization of bacterial cells.