Changes in the Fatty Acid Composition of the Marine Ciliated Protozoan Parauronema acutum with Increasing Culture Age and Adaptation to Changing Sodium Chloride Concentrations

Changes in the fatty acid composition of the membrane lipids of the marine ciliate. Parauronema acutum were studied in ciliates harvested from early logarithmic, decelerating logarithmic and stationary phase culture. The relative amounts of 18:1 (9) and 18:2 (9, 12) decreases in both the phospholipid and the neutral sphingolipid fractions with increasing culture age. The content of 18:4 (6, 9, 12, 15), 20:5 (5, 8, 11, 14, 17) and 22:6 (4, 7, 10, 13, 16, 19) in these same lipids increases with culture age. While P. acutum was isolated as a marine ciliate and is usually grown in a medium containing 2.8% NaCl concentration, it actually grows well over NaCl concentration of 1% to 3% and will grow suboptimally without added NaCl. NaCl concentrations above 3% are inhibitory, although suboptimal growth occurs at 5% NaCl concentration. Lipids obtained from ciliates grown at either 1.5% or 2.8% NaCl have essentially identical FAME profiles. Lipids obtained from ciliates grown at either higher or lower concentrations of NaCl show marked changes in FAME profile. In both cases 18:2 (9, 12) content greatly increases while the content of 18 and 20 carbon highly unsaturated fatly acids, particularly 22:6 (4, 7, 10, 13, 16, 19), decreases.