Tribonema cf. minus cultivation in thin-layer raceway pond to uncover its biotechnological potential
摘要
Three cultivation regimes – cultivation in a nutrient-rich medium under sunlight, using the combination of solar and continuous supplementary illumination and the combination of both light sources under nitrogen depletion – were tested in cold-adapted cultures of the filamentous microalga Tribonema cf. minus (Stramenopiles, Xanthophyceae) in an outdoor thin-layer raceway pond. This work aimed to study the potential of growth and biomass production of Tribonema mass culture in moderate climate zones at lower temperatures of early spring. The highest volumetric and areal productivity were 0.28 g L−1 day−1 and 11.2 g m−2 day−1, respectively, which corresponded to the achieved specific growth rate of 0.2 day−1 when sunlight was combined with supplementary illumination. The maximum total fatty acid content, 18.2% of DW, consisting of myristic, palmitic, and palmitoleic acids, was found under nitrogen limitation using supplemental illumination. Diadinoxanthin (Dx) was determined as the main carotenoid in a concentration of 1.22 mg g−1 DW only in the culture grown under sunlight and a nutrient-rich medium in trial 1. The harvested and fermented biomass from trial 3 was used to produce 181 mLN g−1oTS of methane. In these trials, a good correlation was found between changes in the photochemical yield Fv / Fm and the FA content: once Fv / Fm significantly decreased due to nitrogen deficiency, the content of FAs (mostly MUFAs) markedly increased.