Enriching Euglena with Unsaturated Fatty Acids.

n-3 HUFA have been used as feed in rnass cultivation of fish larva.2'5i Recentlydocosahexaenoicacid(DHA)wasrepertedtobethernosteffective n-3 HUFA for the growth of fish fry,6'7) but there is no known method to enrich zooplankton specifically with DHA, In this paper we report on enriching Euglena gracilis with eicosapentaenoic acid (EPA) and DHA, E. gracitis cells are about SO"m in size, contain nutritious proteins and vitamins8'9) and are so readily digested by erdinary digestive enzymesiO) that they are thought to be useful as feed for zooplankton in fish larva production. E. gracilis was reportedii) to be a good nutrient seurce for rotifers and Artemia, the zooplankton used in mass growing of fish fry, but to contain relatively little n-3 HUFA.i2'i6) Accordingly enriching the protozoa by such fatty acids should proyide a highly profitable feed for the zooplankton. Thus, the' n-3 HUFA-enriched zooplankton obtained are expected to enhance fish fry procluction, E, gracitis strain Z was grewn at 28MC in a medium composed ef 2% glucose, O.7% ammenium sulfate, e.5gS cern steep liquor, mineral$ (O.5% MgS04'7H20, e,5% KH,PO,, O.2% CaCO,, O,OS% Na, EDTA, O.05% FeS04(NH4)2SO,'6H,O, O.025% ZnSO,・7H,O, O.O18% MnSO,・45HiO) and vitamins (5mglliter vitamin B,, le"g/liter vitamin Bn) for 48 h in the dark. After the addition of O-I% of fatty acids, cultivation