Moniliella tomentosa var pollinis was cultivated on complex medium consisting of glucose as carbon source, urea, (NH4)(2)SO4, corn steep liquor and yeast extract as nitrogen sources, respectively. The pH and the concentrations of (dry) cell mass, glucose, erythritol, ribitol, glycerol, disaccharides, trisaccharides, polysaccharides, amino acids in medium, oxygen and carbon dioxide in off-gas were monitored during the cultivation. Rates of growth, substrate uptake and production, yields and yield coefficients as well as OUR, CO2 production rate and respiratory coefficient were evaluated with different medium composition and operating conditions with two mutants in 801 bubble column and 801 airlift tower loop reactors in batch and fed-batch operation. Foam height, gas hold up, bubble velocity, and specific gas/liquid interfacial area were measured in situ. The proteins in medium were investigated with SDS-PAGE. At high concentrations (up to 500 g 1(-1)) high (dry) cell mass concentrations (up to 65 g 1(-1)), high erythritol concentrations (up to 175 g 1(-1)) erythritol yield (43%) and yield coefficients (0.58 g g(-1)) as well as polyol concentrations (250 g 1(-1)) polyol yield (60%) and yield coefficients (0.70 g g(-1)) were obtained under optimal conditions. With a mutant somewhat better results were obtained. Under oxygen limitation ethanol was formed, and under nitrogen limitation strong foam formation impaired the production process. By suitable aeration and fed-batch process using mixture of glucose and nitrogen source for feeding, ethanol and foam formation could be reduced and eliminated, respectively. The strong effect of antifoam agent in the medium on the fluid dynamic of the two-phase system and the dissolved oxygen concentration was demonstrated. (C) 2002 Elsevier Science Ltd. All rights reserved.