Bacteriolytic action of fluoride ions

Bacillus subtilis, Neisseria subflava, and LYT coccus were found to undergo massive lysis after growth in media containing 0.01 to 10 mM NaF. When cells of these organisms were transferred from late-exponential-phase cultures to 0.02 M sodium phosphate buffer plus 0.1 M KCl, they underwent spontaneous autolysis. Cells grown in media with fluoride were more liable to autolysis, and walls isolated from them also showed enhanced autolytic sensitivity, even though added fluoride did not directly stimulate autolysins. Sporadic or partial lysis occurred in populations of Streptococcus sanguis and Streptococcus mutans BHT or LM-7 after growth in fluoridated media. Most bacteria that were tested did not undergo fluoride-induced lysis. However, cells of all test bacteria were found to have reduced amounts of peptidoglycan per unit of cell weight when grown in the presence of fluoride. Incorporation of labeled lysine or glucosamine into peptidoglycan (Park-Hancock residue) was stimulated, instead of inhibited, by fluoride. However, fluoride also stimulated the loss of radioactivity from Park-Hancock residues of cells that had previously incorporated labeled lysine or glucosamine. Thus, fluoride appeared to enhance peptidoglycan turnover, and this turnover reduced the peptidoglycan contents of all bacteria tested, but induced lysis in only those bacteria that normally have highly active autolytic systems.