Alginate-derived oligosaccharides (AOS) enhance the biomass of Phaeodactylum tricornutum and fucoxanthin yield
摘要
Fucoxanthin has high economic value due to its bioactivity. Currently, fucoxanthin production faces challenges, such as limited biomass and inhibition of fucoxanthin synthesis in the diatom Phaeodactylum tricornutum with increasing light intensity. This study demonstrated that the addition of alginate-derived oligosaccharides (AOS) promoted biomass and fucoxanthin synthesis in P. tricornutum, thereby alleviating the inhibition of increasing light intensity on the fucoxanthin yield. The highest fucoxanthin yield in the AOS-treated groups reached 19.7 mg g−1 under a light intensity of 50 μmol photons m−2 s−1 after a 16-day cultivation period, resulting in a 34% increase when compared with the control group. Under a high light intensity (300 μmol photons m−2 s−1), the AOS-treated groups had also nearly double the biomass of the control group, and the fucoxanthin content per unit of dry weight in the AOS-treated groups was 17% higher than that in the control group. The positive effects of AOS on fucoxanthin yield were attributed to two factors. Firstly, the AOS enhanced the photosynthetic electron transport rate and oxygen evolution rate, which effectively slowed down biomass decline due to high-light stress. Secondly, the AOS upregulated key genes (PSY, PDS1, ZEP1, ZEP2, CRTISO2, and CRTISO5) associated with fucoxanthin synthesis. This study demonstrated that AOS addition is a feasible strategy for enhancing fucoxanthin production, which could facilitate the scaled-up production of fucoxanthin.