Interactions during inhibition of growth of Aspergillus parasiticus by gentian violet.

The interrelationships of gentian violet and the growth of Aspergillus parasiticus NRRL 2999 were investigated with static cultures in a yeast extract-sucrose liquid medium. The dye was fungistatic but not fungicidal at concentrations up to 32 microgram/ml. Growth inhibition was dependent on the concentration of the added dye and on the age of the culture. At 8 microgram/ml with a spore inoculum, growth was inhibited for 6 days while 32 microgram/ml added to a 4-day-old culture inhibited for only 24 hr. Initiation of a normal rate of growth coincided with disappearance of the dye from the medium. The disappearance followed first order kinetics. The dye appeared to bind to the mycelium prior to its apparent disappearance from the medium. Gentian violet appeared to inhibit spore germination by inhibiting a critical point in the spore swelling phenomenon. In addition, growth subsequent to germination was retarded.