Screening And Pilot Scale Cultivation Of Fucoxanthin-rich Microalgae

Firstly, water and soil samples from freshwater, seawater and soil in Sanya andWanning of Hainan Province at different seasons were collected. The samples wereseparated using the micromanipulation system and purified. The18S rDNA of theseparated algae were analysed to identify the species. The two kinds of algae,Phaeodactylum tricornutum and Isochrysis galbana, were chosen to investigate.Secondly, the experiment about the effects of different temperature, differentintensity of illumination and different light quality on P. tricornutum and I. galbanawere carried out, and three parallel samples were set under each condition. For P.tricornutum, the conditions include different temperature (20℃,25℃,30℃),different intensity of illumination (160μmol·m–2·s–1,90μmol·m–2·s–1,50μmol·m–2·s–1)and different light quality (red light, green light, blue light). For I. galbana, theconditions include different temperature (30℃,33℃,36℃,38℃), different intensityof illumination (490μmol·m–2·s–1,440μmol·m–2·s–1,180μmol·m–2·s–1,90μmol·m–2·s–1) and different light quality (red light, green light, blue light). The resultsindicated that the growth and fucoxanthin content were promoted under conditions of25℃,90μmol·m–2·s–1and red light for P. tricornutum and conditions of30℃,90μmol·m–2·s–1and green light for I. galbana.Then, the fatty acid composition of I. galbana was determined and four kinds offlocculants (ferric chloride (FC), aluminum sulfate (AS), aluminum potassium sulfate(APS), polyaluminum chloride (PAC)) were used to improve the efficiency ofcollecting algae. At the same time, the experiment about the effects of differentflocculants on I. galbana was carried out. The result showed that I. galbana couldgrow after treated with different flocculants. The biomass of I. galbana treated withFC and AS were lower than I. galbana that was cultivated normally, whereas thebiomass of I. galbana treated with APS and PAC were higher than I. galbana that wascultivated normally, and the biomass I. galbana treated with PAC was highest. Compared with I. galbana that was cultivated normally, the PSII activity andfucoxanthin content of I. galbana treated with four kinds of flocculants wereincreased, of which I. galbana treated with FC had the highest PSII activity, I.galbana treated with APS had the highest content of fucoxanthin and I. galbanatreated with PAC followed.Finally, in order to achieve the industrial production of fucoxanthin, P.tricornutum and I. galbana were cultivated in pilot scale at algae farms in Wanning,Hainan Province. The results indicated that P. tricornutum couldn’t survive in pilotscale at outdoor condition and I. galbana grew normally and was collected in the wayof flocculation and settling processes. These phenomena showed that the cultivationof I. galbana in pilot scale was convenient and feasible and I. galbana could be usedas the raw materials to extract fucoxanthin, which laid the foundation for theindustrial production of fucoxanthin.