FIG. 7.

Dialysis bag experiment. Cells of desA mutant strain PR6080 containing no polyunsaturated fatty acids (6) were grown at 38°C in medium A-U (150 ml in a glass tube [34 by 295 mm]) with 1% (vol/vol) CO₂ in air (OD₅₅₀, approximately 1), and 25 ml of the culture was placed into a dialysis bag (17.5-mm diameter; molecular weight cutoff, 6,000 to 8,000). Linoleic acid [18:2 (9, 12); 150 μl of a 0.5 M solution in methanol] was added to the cell culture inside the dialysis bag (A) or to that outside the bag (B). The calculated final concentration of free fatty acids was 0.5 mM, but lipid droplets could be seen floating on the surface of the culture medium. After 2 to 3 days of incubation under standard culture conditions, cells in contact with the fatty acid-containing solution were killed and bleached. The dialysis bags were taken from the culture tubes and photographed.