Abstract
An aquatic filamentous fungus, Saprolegnia sp. 28YTF-1, was found to accumulate odd chain polyunsaturated fatty acids (PUFAs)of 17 to 19 carbon chain length, when grown with fatty acids with 13, 15, or 17 carbons. A novel ω2 PUFA identified as 5, 8, 11, 14, 17-cis-nonadecapentaenoic acid (19 : 5ω2) was detected as one of the major PUFAs, together with 5, 8, 11, 14-cis-nona-decatetraenoic acid (19 : 4ω5), in both nonpolar and polar lipids from the mycelia. The biosynthetic route to 19 : 5ω2 was presumed to mimic the ω6 route to arachidonic acid (20 : 4ω6) and ω3 de-saturation of 20 : 4ω6 to 5, 8, 11, 14, 17-cis-eicosapentaenoic acid (20 : 5ω3), as follows : 15 : 0→17 : 0→17 : 1→17 : 2ω5→17 : 3ω5→19 : 4ω5 → 19 : 5ω2.
