Demand for fatty acids is increasing at an annual rate of 17%, due to their increased use in the oleochemical and transport industries. Presently, vegetable oils are the major source of fatty acids, whereas lipids with fatty acids similar to those of some vegetable oils have been reported to be synthesized by oleaginous microorganisms. In the present study, the culturing conditions for the oleaginous yeast Rhodotorula minuta IIP-33 have been optimized. In contrast to the lipid accumulation characteristics of most oleaginous yeasts, a carbonto-nitrogen ratio of 30 was favorable for maximal accumulation of lipids (48%) with 22.5% conversion of glucose as carbon substrate. The lipids contained fatty acids in the C 7 -C 18 range, the relative composition of which varied with culture temperature. JAOCS 75, 501-505 (1998).Natural fatty oils are the major source of fatty acids used as feedstock in the oleochemical industries. With the growing demand, at 17% per annum, for fatty acids in the oleochemical industries and the recent application of fatty acid esters as biodiesel and biodegradable lube oils (1,2), the feasibility of using microorganisms as the alternate source of fats and oils would be an attractive proposition. Biosynthesis of lipids, such as triglycerides, phospholipids and glycolipids, by some oleaginous yeasts has been well documented (3,4). Synthesis of fatty acids in oleaginous yeasts is facilitated by a decrease in the activity of the isocitrate dehydrogenase enzyme under diminished nitrogen levels in the culture (5).Temperature-induced changes are reported in the fatty acid composition of the accumulated lipids of various oleaginous yeasts (6). Thus, synthesis of lipids with varying fatty acid composition should be feasible by culturing oleaginous microorganism under different conditions.We report here the growth and lipid accumulation characteristics of a rarely explored yeast strain of Rhodotorula minuta. The effect of growth temperature on the regulation of fatty acid synthesis by the strain has also been investigated and reported. EXPERIMENTAL PROCEDURESYeast strain and culture media. The yeast strain was isolated from mineral oil-contaminated local soil and was identified as R. minuta. The strain grows in red-pigmented colonies on YPD agar plates or in YPD aqueous medium within a temperature range of 28-36°C. The strain was preserved on YPD agar slants and stored at 5°C. Preparation of inocula and growth studies of the strain were conducted in a synthetic medium (OP24) that contained the following major constituents (w/w %): D-Glucose, 2; MgSO 4 ·7H 2 O, 0.07; (NH 4 ) 2 SO 4 , 0.2; Na 2 HPO 4 ·2H 2 O, 0.07; KH 2 PO 4 ·2H 2 O, 0.12; and ZnSO 4 , CuSO 4 , and FeSO 4 in traces. Carbon-to-nitrogen (C/N) ratio was increased by adding excess glucose in the medium at the end of the growth phase.Preparation of inocula. The yeast strain R. minuta IIP33 was grown to the exponential growth phase (o.d. 0.8) in 250-mL Erlenmeyer flasks that each contained 50 mL of growth medium (OP24), incubated at a temperat...