As yet, flow cytometry is not used so widely in microbiology as in some other disciplines. This volume presents contributions flow cytometry to study a from research microbiologists who use diverse set of problems. It illustrates the power of the technique, and may persuade others of its usefulness. Most of the con tributors gathered in Cardiff on 23 October 1991, at a meeting organized for the Royal Microscopical Society by Dr. Richard Allman, but the content of their chapters is not limited by the discourse of that meeting, and for balance other experts were invited to write for this book. Flow Cytometry in Microbiology thus represents the first collection of articles specifically devoted to the applications of a technique which promises so much to those investigating the microbial world. Cardiff, 1992 David Lloyd Contents List of Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix 1 Flow Cytometry: A Technique Waiting for Microbiologists David Lloyd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 The Physical and Biological Basis for Flow Cytometry of Escherichia coli Erik Boye and Harald B. Steen . . . . . . . . . . . . . . . . . . . . . . 11 3 Flow Cytometric Analysis of Heterogeneous Bacterial Populations Richard Allman, Richard Manchee and David Lloyd. . . . 27 4 On the Determination of the Size of Microbial Cells Using Flow Cytometry Hazel M. Davey, Chris L. Davey and Douglas B. Kell . . 49 5 Uses of Membrane Potential Sensitive Dyes with Bacteria David Mason, Richard Allman and David Lloyd . . . . . . .