Measurement of bacterial (E. coli) concentration by flow cytometry.

Abstract

Periodontitis is a multi-microbial disease and the comparison of a series of periodomtopathogenic and nonperiodontopathogenic bacteria in terms of microbe-host interaction may provide clues to understand the microbial etiology of the disease better. When we deal with twenty different bacterial specles in a study, the first technical issue is how to measure the accurate concentration and use the same number of bacterial cells. We measured bacterial concentration by enumerating bacteria stained with SYTOX green for constant time using a flow c ytometer and compared the results with those obtained by plate counting. Concentrations claculated by two different methods were very close. Therefore, flow cytometric counting allowed the rapid analysis of liver/dead bacteria, offering the advantage of turbidity measurement and that of colony counting together.