Morphological changes in Escherichia coli and Bacillus cereus caused by external histone.

It was found that the externally added histone changes remarkably both the surface and the internal ultrastructure of cells of Escherichia coli. The interaction of histone with surface structures results in thickening of the inner layer of the cell wall. Cytoplasm becomes condensed, contains extensive electrontransport zones and neither ribosomes nor the nuclear structure are differentiated. The addition of histone to germinating spores of Bacillus cereus decelerates germination and postgerminative development of this organism and changes ultrastructure of the external surface of the exosporium. The addition of Mg2+ ions reverting the effect of histone results in a renewal of the original ultrastructure of the exosporium.