FLOW CYTOMETRIC ANALYSIS OF ENTIRE MICROBIAL COLONIES

Much could be gained if the scope of flow cytometry could be broadened to the study of entire cell colonies, rather than to populations of s ingle, separate cells. This can be achieved by encapsulating single mi crobial cells in small spheres in a way that allows each cell to multi ply and form a colony within its respective microbead, which is then a menable to analysis by flow cytometry. Methods for performing the enca psulation within beads of appropriate size and homogeneity have been d eveloped (Nir et al., Appl. Environ. Microbiol. 56:2870-2875, 1990). W e describe here how a variety of properties of the entrapped colonies, such as mass, growth rate, enzymatic activity, and expression of spec ific antigens, can be measured, and we discuss how these constructs ca n be utilized to select microbial mutants. (C) 1994 Wiley-Liss, Inc.