A new strain of benthic diatom Cylindrotheca fusiformis producing fucoxanthin (Fx) and polyunsaturated fatty acids (PUFAs) proved to be promising for biotechnology. Identification of Fx was carried out from the analysis of
the ultraviolet and visible (UV-VIS) absorption spectra, electrospray ionization mass spectra (ESI MS) and proton
magnetic resonance spectra (
1
H NMR). The specific growth rate of the culture was 0.52 1/day, and the maximum
productivity 1.56 g/(L × day). The accumulation rates of eicosapentaenoic and arachidonic acids in the stationary growth phase were 4.5 and 3.2 mg/(L × day), respectively, and that of Fx was 6 mg/(L × day). The
accumulation of PUFAs in the biomass reached 4.68% of dry weight. The Fx content in the biomass reached 21.4
mg/g. The strain settles to the photobioreactor bottom in the absence of mixing, which property simplifies the
biomass harvesting.