PHYSICAL METHODS FOR OBTAINING SYNCHRONOUS CULTURE OF ESCHERICHIA COLI

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Abstract
Two types of cells, a larger type (mature) and a smaller type (immature), were separated by means of physical methods from logarithmic phase cultures of Escherichia coli strain B. Fractional sedimentation in a sucrose solution of a specific gravity of 1.245 yielded good separation, but the cells thus obtained showed an abnormal growth curve presumably due to osmotic injury. In contrast, fractional filtration, based on the paper chromatopile technique used in chemical analysis, had no injurious effects and, there-fore, constitutes a more desirable method. A stepwise growth curve, indicative of synchronous divisions, was obtained with the cell fractions after inoculation into fresh media.