[The marine diatom Chaetoceros simplex calcitrans Paulsen and its environment. Effects of light and ultraviolet irradiation on the biosynthesis of fatty acids].

In continuous light (24/24 h) or with a 12/24 h photophase, the title diatom synthesizes the same total amount of fatty acids. But the photophase considerably increases some of them: C 18:2 (+535%), C 17:2 (+422%), C 17:0 (+97%), C 19:0 (+97%), C 17:1 (+72%). Adding ultraviolet irradiations to the two mentioned conditions of light also increases the total amount of fatty acids and induces the biosynthesis of the C 20:0. The results are discussed.