Fatty Acids of Rhodotorula gracilis : Fat Production in Submerged Culture and the Particular Effect of pH Value

SUMMARY Rhodotorula gracilis growing in batch culture exhibited acceleration, exponential and linear phases of growth. In a fourth phase, following nitrogen exhaustion, the concentration of lipid in the culture increased, but it is suggested that the rate of lipid production was not stimulated but remained constant, the apparent increase being almost entirely due to the absence of cell proliferation. No significant changes occurred in the fatty acid composition of the lipid when nitrogen was exhausted. At low pH values, growth of the organism was retarded, but the lipid production rate increased although the final concentration of lipid remained the same. The ratio of unsaturated to saturated fatty acids also decreased principally due to a lowered concentration of oleic acid but the concentration of myristic, stearic, linoleic and linolenic acids increased.