Cold-adapted culturing of the microalga Monoraphidium sp. in thin-layer raceway pond for biomass production

Abstract

Three cultivation regimes were tested in cold-adapted cultures of the green microalga Monoraphidium in an outdoor thin-layer raceway pond: cultivation under sunlight; its combination with continuous supplementary illumination; and nitrogen depletion using both light sources. The highest volumetric and areal productivity, 0.16 g L−1 d−1 and 3.22 g m−2 d−1, respectively corresponding to the specific growth rate μ of 0.191 d−1 were achieved when sunlight was combined with supplementary illumination. The maximum total fatty acid content, 20.29 % of DW, rich in oleic acid, 54 % of total fatty acid content, was achieved under nitrogen depletion stress. An outstanding amount of lutein, 26.39 mg lutein g−1 DW, was detected grown under sunlight in the first trial. From the harvested and fermented biomass in the second trial 236 mLN g−1oTS of methane was generated.