Inhibition of sporulation by acid fuchsin.

Abstract

Certain members of the triphenyl-methane series of dyes are now known to have an inhibitory effect on bacteria. This is particularly true of the basic dyes like gentian violet which are capable of impeding many of the active processes of the Gram-positive bacteria, of preventing their growth in very weak dilution, and even of killing them. These types are less potent in their action on Gram-negative bacteria. The acid dyes of this series (like acid fuchsin) are much weaker in bacteriostatic action than the basic dyes; indeed, in order to bring out their power at all, long exposure to fairly strong solutions (preferably at slight elevations of temperature) are needed. So far as acid fuchsin exhibits selective activity at all, it behaves (at least under experimental conditions in which bacteriostatic and bacteriocidal powers are combined) quite differently from the basic dyes.

In general, four effects of tri-phenyl-methane dyes on bacteria have been observed. These dyes bring moving bacteria to rest, they inhibit fission, they impede sporulation, they bring about a state of suspended animation and they kill. By choosing the dye and the organism used in the experiment, any or all of these results may, within limits, be produced at will.

The present communication has to do with the prevention of sporulation caused by exposures of B. subtilis to acid fuchsin. The phenomenon which has been observed appears to be similar to observations made on other dyes by Behring, 1 ROUX, 2 Flexner and Noguchi, 3 and Noguchi. 4

Plants from a 24-hour culture of B. subtilis were made on petri dishes, covering the entire surface of the agar, and allowed to grow 3 hours. Smears made at this time showed the growth to consist almost entirely of vegetative forms.