Lipids of Haliphthoros philippinensis: An oomycetous marine microbe

Lipids of the marine oomycetous microbe Haliphthoros philippinensis were ch aracterized by chromatographic and spectroscopic techniques. Total lipid co ntent of this organism was relatively low and not very responsive to manipu lation of the culture conditions. Neutral lipid comprised 21% of the total lipid and the polar lipids were mainly phosphatidylcholine (44%), phosphati dylethanolamine (15%), and a ceramide-phosphorylethanolamine (19%). Palmiti c (16:0) was the primary saturated fatty acid at 25% of the total fatty aci ds, 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. F ucosterol was the principal sterol at 59% of the total sterols. The effects of several cultivation variables on growth and EPA production by this spec ies were investigated. Among those tested, glucose and sodium glutamate wer e the most efficient carbon and nitrogen sources for growth, respectively. When the mycelium was cultivated for 6 d to produce biomass under optimal g rowth 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 gl ucose 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 degrees C, and 56% over that cultured at 16 degrees C for 13 d. ARA production did not respond accordingly.