The bactericidal and bacteriostatic action of crystal violet

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Abstract
The bacteriostatic and bactericidal action of crystal violet are considered separately. Above a certain conc. the dye acts as a characteristic disinfectant. The cells die logarithmically and proportionately to the dye conc. Old cells are more resistant than young cells and the death rate is independent of the inoculum. The dye toxicity increases slightly with an increase in pH. This action is probably due to the combination of the dye with some indispensable cell constituents. At lower conc., the dye does not give a logarithmic survivor curve, and the bactericidal action is not influenced by the cell age or pH of the dye conc. This unusual effect may be due to the unfavorable oxidation-reduction potential poised by the dye. In this range the cells usually start multiplication after an extended lag period which increases with the dye conc. up to a place where no multiplication occurs. Once started, multiplication proceeds at a normal rate. The length of the lag period is inversely proportional to the logarithm of the number of inoculated cells. It increases with the O2 conc. and pH. Young cultures recover more quickly than old ones. The bacteriostatic effect of the dye is due to its property of poising the potential in a range unfavorable for cell multiplication.