Abstract:In order to promote the high-yield production of fucoxanthin in mixotrophic Phaeodactylum tricornutum, the concentration and combination of multiple phytohormones were optimized in this study. The results showed that with the fucoxanthin yield as the index, the optimal final mass concentrations of 3-indoleacetic acid, indole-3-carboxaldehyde and salicylic acid (0.4 mg/L) were determined to be 0.37, 0.042 and 0.4 mg/L, respectively. Further optimization revealed that 0.37 mg/L indoleacetic acid and 0.4 mg/L salicylic acid were the optimal combination, resulting in the increase of fucoxanthin yield to 4.53 mg/(L∙d). The combination was further recombined with phytohormone-like calcium lignosulfonate (10 mg/L), and the production capacity was evaluated in a 5-L photo-fermenter. The results showed that at the end of photo-fermentation, the cell density (1.20×108 cells/mL), specific growth rate (0.25 d), biomass concentration (4.17 g/L), biomass production rate (367.09 mg/(L∙d)) as well as fucoxanthin content (16.61 mg/g) and yield (6.93 mg/(L∙d)) reached the highest value. Biomass production rate, fucoxanthin content and yield increased significantly increased (by 28.42%, 40.05%, and 65.00%, respectively) (P<0.05) compared with those in the absence of added phytohormone. A technology based on synergistic phytohormone combination was developed in this study, which significantly increased the biomass yield and fucoxanthin production rate, thereby providing a new technical support for the high-yield production of fucoxanthin in mixotrophic Phaeodactylum tricornutum.
