Studies on protein production by yeasts. III. Effects of different levels of nitrogen and phosphorus

The four strains of yeasts that gave good growth in molasses medium, short generation time, and high protein content were selected for further studies in a trial for increasing their yield and protein content. Therefore, the effect of different levels of ammonium sulphate and potassium dihydrogen phosphate on the growth and protein synthesis of the strains was investigated, using molasses as a source of carbon. The results revealed that the most suitable concentrations of ammonium sulphate in the propagation medium lie between 0.40 to 0.55% for the production of high yield and protein content of strains S. cerevisiae (Gr. 104), C. utilis (F. 86), C. tropicalis (F. 35), and H. anomala (Gr. 5). The optimum concentration of potassium dihydrogen phosphate lies between 0.2 to 0.3% for the same strains. S. cerevisiae (Gr. 104) seemed to be the most efficient strain that gave the best growth, high percentage of protein, and essential amino acids in molasses medium.