EFFECT OF DESERTOMYCIN ON CELL-WALL POLYM ER SYNTHESIS IN SACCHAROMYCES-UVARUM

The desertomycin action upon Saccharomyces uvarum wall synthesis has b een studied. Spheroblast regeneration was carried out in a Liquid medi um containing labeled glucose to monitor the synthesis of different wa ll components. In the presence of desertomycin, wall synthesis was aff ected; this was expressed as a net reduction of insoluble alkali const ituents content, more precisely the insoluble acido-alkali fraction th at, in yeasts, is constituted by chains of beta(1,S)-glucans linked am ong themselves by beta(1,6) bonds. Mannan formation was not inhibited; such polymers that cannot be fixed to the glucan matrix of the wall w ere liberated in the regeneration medium. Because of desertomycin acti on, the decrease in insoluble alkali content revealed an interference with the enzymatic systems catalyzing glucan synthesis. In vitro, howe ver, this antifungal had little effect upon glucan synthetase activity : doses 5 times superior to the subinhibiting level used in vivo caus ed only 30% inhibition. This result can be explained by an indirect ac tion of desertomycin. Parietal disorders were the result of membrane s tructure disturbance, notably the phospholipids and localized enzymati c systems. This antifungal presents an analogical structure with macro lides with recognized membrane action.