Effect of Papulacandin B on the Cell Wall and Growth of Geotrichum lacti

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Abstract
Addition of the antifungal antibiotic papulacandin B to an exponential culture of G. lactis inhibited incorporation of glucose into the alkali-insoluble and alkali-soluble glucan fractions of the hyphal wall; however, the rate of growth was practically unaltered. Synthesis of other cell wall components (i.e., galactomannan and chitin) was not affected. Papulacandin B also induced the proliferation of branches along the hyphae which continued to branch dichotomously, resulting in a ''colonial'' pattern of growth. Aculeacin A, another antifungal antibiotic that inhibited .beta.-glucan synthesis, also caused morphological alterations similar to those described for papulacandin B. Inhibition of .beta.-glucan synthesis and the altered growth pattern persisted for several hours after removal of the antibiotic. Recovery of .beta.-glucan synthesis and restoration of the normal pattern of growth occurred simultaneously. Growth of G. lactis in L-sorbose medium also led to inhibition of .beta.-glucan synthesis and dichotomous branching.