Effect of papulacandin B on the cell wall and growth of Geotrichum lactis.

Addition of the antifungal antibiotic papulacandin B to an exponential culture of Geotrichum lactis inhibited incorporation of glucose into the alkali-insoluble and alkali-soluble glucan fractions of the hyphal wall, although 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.