Spores of microorganisms. XXI. Conversion of outgrowing spores of Bacillus cereus to refractile forms by basic peptides and proteins

Inhibitory effect of 1-methyldodecyldimethylamine oxide and N,N-bis(dodecyldimethyl)-1,2-ethanediammonium dibromide on the spores of Bacillus cereus

1-Methyldodecyldimethylamine oxide (MDDO) and N,N'-bis(dodecyldimethyl)-1,2-ethanediammonium dibromide (BDED) exhibit a significant affinity for the surface of Bacillus cereus spores and adsorb very rapidly to the cells; they have a pronounced inhibitory effect on spore outgrowth. In order to alter the affinity of the spore surface for these inhibitors, the spores were pretreated with sodium dodecyl sulfate (SDS), and with an electronegative (Tween 80) and electropositive (histone) compound. In SDS-pretreated spores the inhibitory effect of MDDO and BDED was abolished to a considerable extent. Whereas the development of intact spores was inhibited already after germination, in SDS-pretreated spores the postgermination development continued but was not completed. In Tween 80-pretreated spores the addition of BDED led only to a retardation of outgrowth and division; BDED added only during the division stage interrupted further development completely. Histone-pretreated spores stopped their development instantaneously after the addition of BDED at any phase of the postgermination development. The possible mechanisms of the interaction of the compounds used with spore surface or rather with the state of its structures are discussed.

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.

Change in the absorbancy of bacterial suspensions before initiation of growth

The apparent absorbancy of suspensions of stationary-phase cells of Streptococcus lactis strain 354/07 decreased immediately after being placed in fresh media. This optical effect also occurred in defined mixtures of buffer glucose and KCl. CaCl(2) caused the absorbancy to increase. CaCl(2) and KCl together had about the same effect as KCl alone. SrCl(2) could replace CaCl(2), but it was less effective by a factor of 10(2). MnCl(2), MgCl(2), and NaCl were without effect. The absorbancy did not change when cells were first killed by p-chloromercuribenzoate or when the reaction was carried out at 0 C. The rate of the reaction was dependent on temperature and concentration of glucose and salts. Gradient centrifugation suggests that this optical effect was caused by change in the refractive index of the test organism rather than by change in volume. Nine other organisms representing four additional genera gave the same optical effect as S. lactis 354/07. Two other organisms reacted feebly whereas another strain of S. lactis reacted in the opposite way, the absorbancy of the suspension increasing instead of decreasing. Spores of Bacillus cereus did not respond.