Confocal Laser Microscopy and Digital Image Analysis in Microbial Ecology

Microbial ecologists have extensively explored the potential applications of light microscopy for more than five decades (Henrici and Johnson, 1935; Perfil’ev and Gabe, 1969; Casida, 1969, 1972, 1975, 1976; Staley, 1971; Caldwell and Hirsch, 1973; Caldwell et al., 1973, 1975; Caldwell and Tiedje, 1975a,b; Labeda et al., 1976; Hirsch, 1977, 1980; Geesey et al., 1978; Marshall, 1986). Now traditional microscopy has given way to “microvisualization” (Friedhoff, 1991) greatly accelerating research. Microorganisms are no longer merely photographed; instead, they are digitally “imaged” using fluorescent molecular probes, confocal laser microscopy, and computer image analysis. The chemical and biological relationships between a microorganism and its microenvironment are seen directly, nondestructively, in situ, and in “real time” (Lawrence and Caldwell, 1990). Consequently, it is no longer necessary to disrupt microbial communities when studying the molecular or behavioral aspects of their ecology.