EFFECT OF THE MICROTUBULE INHIBITOR METHYL BENZIMIDAZOL-2-YL CARBAMATE (MBC) ON PRODUCTION AND SECRETION OF ENZYMES IN ASPERGILLUS-NIDULANS

The effect of the antimicrotubular drug methyl benzimidazol-2-yl carba mate (MBC) on the production and secretion of acid phosphatase, alpha- galactosidase and beta-galactosidase in Aspergillus nidulans was studi ed. A wild type and two benomyl resistant mutant (benA10 and benC28) s trains were used. All the strains secreted acid phosphatase and alpha- galactosidase into the culture medium, whereas beta-galactosidase rema ined in the mycelium with a portion of its activity bound to the cell wall. When the wild type strain was incubated in the presence of a sub lethal dose of MBC, a decrease of the activity of the enzymes studied was found. A reduction in the secretion of acid phosphatase and alpha- galactosidase into the culture medium was also observed. In addition, a decrease in the percentage of alpha- and beta-galactosidase activiti es bound to the cell wall was detected. The MBC dose used for the wild type strain did not modify either the total enzyme activities or the secretion of the enzymes studied in the benomyl resistant mutant benA and benC strains. However, when those strains were grown in the presen ce of a sublethal dose of MBC, a decrease in the total enzyme activiti es, as well as a reduction in acid phosphatase and alpha-galactosidase secretion was found. In addition, alterations in the percentage of en zyme activities bound to the cell wall were observed in both mutant st rains. Results described in this work clearly suggest that microtubule s are involved in the polarized secretion of enzymes in A. nidulans.