[Irregular growth of Escherichia coli under periodic cultivation conditions]

Uneven growth of Escherichia coli ML 30 was found in periodic conditions of cultivation on a defined medium containing maltose or glucose as a source of carbon. This is demonstrated by changes in the slope of the logarithmic curve expressed in units of optical density, and the curve of the specific growth rate plotted against time. The uneven pattern of growth can be revealed only if samples are taken every 15 min. Variations in the growth rate are accompanied with irregular utilization of carbon sources, acidification of the medium, accumulation of organic acids in the cultural broth, deviations in the enzyme activity and the content of polymers in the cells. According to the dynamics of the aforementioned parameters, the growth phase of E. coli is complex and can be subdivided into five different cycles. Such a synchronization of growth is presumed to be due to changes in the composition of the growth medium.