Solid-state-fermentation in fluidized beds using gas as continuous phase enables working in water reduced systems. Better temperature and humidity control could be realized because of homogenious process conditions in fluidized beds. The studies shown, deal with solid-state-fermentation of solid yeast particles (Saccharomyces cerevisiae) in fluidized beds. Technical improvement as well as better control of the spraying system enable fluidization of yeast in the range aw < 0,96 without the use of fluidization assistance. The nutrient supply was realized by the spraying system. The influence of nutrient flow (glucose, salts) on hydrodynamic and metabolism of solid yeast particles has been determined. Nutrient solution addition rates, beyond which fluidization characteristics and metabolic activity are greatly impaired, are too small to realize generations rates comparable to submerged cultures.