[Production of yeast biomasses from starch]

The well known fodder yeasts do not accumulate extracellular amylolytic enzymes and are therefore unable to utilize starches for the production of microbial biomasses. Some of the Endomycopsis yeasts produce glucoamylase but their specific growth rate is so small that continuous cultivation in starch containing media results in low productivites. In the "Symba-process" this drawback is overcome by a twostage fermentation process. In the first stage only Endomycopsis fibuliger yeasts are continuously cultivated and in the second stage the main part of the starch containing medium is converted to microbial biomasses by a mixed culture consisting of fodder yeasts (p.a. Candida utilis) and Endomycopsis fibuliger transferred continously from the first stage. In this work methods for evaluating conditions of cultivation of such a process are presented and a two stage continuous fermentation of a starch containing medium is performed. In the second stage with a dilution rate of D Y 0,174 h-1 a productivity of 1,7 g dry biomasses/1-h was attained Methods for improving the productivity are discussed.