Lipids of Haliphthoros philippinensis: An oomycetous marine microbe

Abstract

AbstractLipids of the marine oomycetous microbe Haliphthoros philippinensis were characterized by chromatographic and spectroscopic techniques. Total lipid content of this organism was relatively low and not very responsive to manipulation of the culture conditions. Neutral lipid comprised 21% of the total lipid and the polar lipids were mainly phosphatidylcholine (44%), phosphatidylethanolamine (15%), and a ceramide‐phosphorylethanolamine (19%). Palmitic (16:0) was the primary saturated fatty acid at 25% of the total fatty acids, and arachidonic acid (20:4n‐6, ARA) and eicosapentaenoic acid (20:5n‐3, EPA) were the major unsaturated fatty acids at 19 and 21%, respectively. Fucosterol was the principal sterol at 59% of the total sterols. The effects of several cultivation variables on growth and EPA production by this species were investigated. Among those tested, glucose and sodium glutamate were the most efficient carbon and nitrogen sources for growth, respectively. When the mycelium was cultivated for 6 d to produce biomass under optimal growth conditions, and then transferred to low temperature for an additional 13 d without glucose, the EPA content reached 31% of the total fatty acids and the yield was 203 mg/L. When the same experiment was performed with glucose supplementation during the low‐temperature phase, EPA composed 27% of total fatty acids and yield reached 316 mg/L, or a 285% increase over that from mycelium cultured for 6 d at 24°C, and 56% over that cultured at 16°C for 13 d. ARA production did not respond accordingly.