The effect of culture conditions, especially nitrogen/carbon ( N / C ) ratio and temperature, on acyl lipid profiles in the oleaginous yeast Rhodotorula glu- tinis N R R L Y 1091 have been investigated. Cultivation of the microorganism under N-limited conditions ( N / C < 0 . 1 4 g/g) resulted in enhanced fatty acid (FA) cell content but a reduced relative amount of polyunsaturated fatty acids (PUFA). The maximal FA productivity was obtained for a 0.025 N / C ratio resulting from the arrangement between the specific rate of FA synthesis and the concentration of lipid-free biomass. Under nitrogen-non-limiting conditions, cells grown at lower temperatures had a higher PUFA content and the maximal productivity of a-linolenic acid was obtained by shifting the temperature of the culture from 30Β°C to 25Β°C. al. 1982), effects of nutrient limitations (Yamauchi et al. 1983), oxygen availability (Choi et al. 1982), pH and temperature (Kessel 1968;Rolph et al. 1989). Among these parameters, only temperature and nitrogen limitation [carbon/nitrogen (C/N) ratio] had a significant effect on lipid content and fatty acid (FA) composition in oxygen-non-limiting culture conditions (Turcotte and Kosaric 1989;Ykema et al. 1988). However, relatively few reports deal with the analysis of kinetics of growth and lipid synthesis (Gill et al. 1977;Hall and Ratledge 1977;Yoon and Rhee 1983; Pan and Rhee 1986a, 1986b).
In the present study, the influence of the initial N / C ratio and of the cultivation temperature on growth and production of lipids and PUFA were investigated in the oleaginous yeast Rhodotorula glutinis, with special emphasis on the kinetic aspects.