POLYOL METABOLISM AND OSMOTIC ADJUSTMENT IN THE MYCELIAL ASCOMYCETE NEOCOSMOSPORA-VASINFECTA (SMITH,E.F.)

The polyols ofN. vasinfecta were predominantly mannitol and arabitol, with minor quantities of glycerol andm-erythritol, when this fungus was grown at minimal osmotic stress (180 mOsm). Growth at increasing osmotic stress (180 to 2640 mOsm) was associated with a progressive decrease in the molecular weight of the most abundant polyol. When the fungus was subjected to osmotic upshock (5 h, 180 to 1040 mOsm), a slight decrease in mannitol was accompanied by a large increase in arabitol, with smaller increases in erythritol and glycerol. This pattern was seen with either KCl or glucose as the osmoticum. This polyol response was inhibited by cycloheximide, suggesting that translational processes were required for its induction. Downshock in growth medium or in isotonic CaCl2 resulted in identical reductions in intramycelial total polyol, and similar polyol patterns by 1 h. There were different fates for the polyol carbon which was lost. Downshock in growth medium resulted in excretion of hexoses and mannitol, while downshock in CaCl2 induced loss to the medium as polyols, in a manner consistent with a simple excretion model. © 1991 Academic Press, Inc.