Significance of Folded Chromosomes Released from Amino-Acid-Starved Escherichia coli Cells

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Abstract
Folded chromosomes from amino-acid-starved E. coli DG 75 are released mainly an envelope-bound complexes which sediment more rapidly than envelope-bound complexes from exponentially grown cells. A minor fraction (.apprx. 3%) represents relatively slow sedimenting envelop-free nucleoids. Morphological analysis of the sensitivity of amino-acid-starved cells to lysozyme and/or detergents indicates that these cells are less susceptible to lysis than exponentially grown cells. This results in the production of fast sedimenting envelope-bound complexes from nondividing cells. It is not the amount of DNA but the low degree of envelope fragmentation that probably causes the high sedimentation rate. After prolonged periods of starvation .apprx. 3% of cells in the process of division persist in the population, indicating that these cells release their (terminated) chromosomes in the envelope-free form. It is not known whether these chromosomes are released because of their detachment from the membrane in situ or because of an enhanced susceptibility of dividing cells to lysis.