Inverse Flocculation Patterns inSaccharomyces cerevisiaeUOFS Y-2330

Abstract

An interesting yeast strain was uncovered which showed an inverse flocculation pattern when cultivated in chemically defined and complex media. When inoculated in a defined medium with glucose as a sole carbon source, this strain immediately flocculated strongly and lost this ability before stationary phase was reached. In a complex malt medium containing glucose, this yeast strongly flocculated throughout the exponential and stationary growth phases. This inverse pattern may be ascribed to a switch in sensitivity of the yeast to flocculate in the presence of glucose as well as pH level, which may, in turn, influence the availability of calcium ions. In both media, matured cells produced protuberances or “wrinkles” upon flocculation as observed by electron and immunofluorescence microscopy. These protuberances may be involved in cell adhesion during the flocculation process.