Synergistic color variants of Aureobasidium pullulans.

Color variants of Aureobasiditlm puliulans were isolated from mao terials collected in tropical and subtropical regions of the world. Three different types of variants produce colonies that are either yellow, red. or purple. When the variants are either mixed with or grown near many different species of yeasts and other microfungi. the rapidity and intensity with which pigment is produced are markedly enhanced. Yellow variants are moderately unstable and change to red. The red varia· ants are highly unstable, changing to yellow. Reversion to the normal wild type is seldom observed. Addition of acid or base causes the pigments to function as pH indicators. Pigment formation is tempera· ture sensitive and mixtures of variants and elicitor strains are colorless at 35 C. but show typical enhancement of pigmentation when removed to 25 C. Variants incubated alone at 35 C show temporary intense pigmentation upon removal to 25 C.