Colony formation and fatty acid composition of marine labyrinthulid isolates grown on agar media

Marine labyrinthulid isolates produced algal lytic zones on the double-layer agar with living cells of diatom, whereas they formed thin film-like colonies on agar media containing bacterial cell extracts or dead cell debris. Phospholipid fraction extracted from bacterial cells such as Vibrio parahaemolyticus stimulated the colony formation of labyrinthulid isolates. The molecular phylogenetic analysis using SSU rDNA sequences indicated that labyrinthulid isolates made a clade with some representatives belonging to the Labyrinthulida. Docosahexaenoic acid (DHA) was found to be the fatty acid with the highest content in cellular lipids of a representative strain L95-2 increasing up to 80% of total fatty acids dependent on culture conditions.