Further analysis of plate count data of bacteria.

Abstract

Our probabilistic view of the colony formation on a plate has led to the hypothesis that the parameter λ in the colony forming equation previously presented reflects the physiological state of a bacterial population. In the present work, the hypothesis was examined with single populations of organisms isolated from soil. These populations showed λ values larger than 1.0 day-1 when grown on a growing medium and less than 0.5 day-1 after starvation in water for several weeks or more. The latter values were similar to those of various soil populations. Cells with a smaller λ proliferated at a lower probability than those with a higher λ. Physiological states corresponding to a λ larger than 1.0 day-1 and less than 0.5 day-1 are designated g and s states, respectively. The transition of cells between the g and s states is discussed.