Comparing three different Phaeodactylum tricornutum strains for the production of chrysolaminarin in flat panel airlift photobioreactors

In recent years, various applications for algae-based beta-1,3-glucans have been postulated, including animal feed and human nutrition. Chrysolaminarin is a beta-1,3-1,6-glucan produced by diatoms such as Phaeodactylum tricornutum for energy storage. It is accumulated under nutrient-depleted cultivation conditions. In this study, the production of chrysolaminarin in artificially illuminated scalable flat panel airlift photobioreactors (FPA) was investigated by using P. tricornutum in a two-stage production process. In the growth stage primarily biomass is produced, and the subsequent nitrogen-depleted stage induces the accumulation of chrysolaminarin. Three P. tricornutum strains (SAG 1090-1a, SAG 1090-1b, SAG 1090-6) were cultured at laboratory scale in 6 L-FPA reactors under controlled light conditions to characterize the process and identify a production strain. The chrysolaminarin content of the algae strains was analysed and additionally their contents of eicosapentaenoic acid and fucoxanthin, both of which could be involved in a possible co-production. Strain SAG 1090-1b exhibited the highest biomass productivity and chrysolaminarin content (317 +/- 9 mg g(DW)(-1)) after nitrogen depletion, and thus stood out as the most suitable for chrysolaminarin production in a two-stage process. A co-production of the three compounds is possible. However, during nitrogen depletion there occurred trade-offs between the compounds. As chrysolaminarin was produced, the amount of fucoxanthin in the culture stagnated or even decreased depending on the selected strain.

Automated summary

In this study, the production of chrysolaminarin by using Phaeodactylum tricornutum in artificially illuminated scalable flat panel airlift photobioreactors was investigated. Among the three P. tricornutum strains tested, SAG 1090-1b showed the highest biomass productivity and chrysolaminarin content, making it the most suitable candidate for chrysolaminarin production in a two-stage process. Co-production of chrysolaminarin, eicosapentaenoic acid, and fucoxanthin is possible, but trade-offs between the compounds were observed during nitrogen depletion.