Chrysolaminarin biosynthesis in the diatom is enhanced by overexpression of 1,6-ß-transglycosylase

Chrysolaminarin is the major form of storage polysaccharides in the diatom Phaeodactylum tricornutum, which is mainly composed of ss-1,3-glucan with ss-1,6-branched chains (molecular weight at 10 kDa). Chrysolaminain has various biological activities such as antioxidant, anti-tumor and immune enhancement. 1,6-ss-transglycosylase is speculated to be the last step in the synthesis of chrysolaminain by adding ss-1,6-branched chains to the main chain of ss-1,3-glucan. In this study, the putative 1,6-ss-transglycosylases (PtTGS1) in P. tricornutum was characterized. PtTGS1 was overexpressed and significantly promoted the chrysolaminain synthesis and reduced lipid synthesis. The continuous accumulation of chrysolaminain was achieved by influencing the shunt of carbon metabolism without affecting the normal physiological state (growth and photosynthesis) of algal cells. These results indicated the important role of PtTGS1 gene in chrysolaminain synthesis and carbon shunt pathways.

Automated summary

In this study, the putative 1,6-ss-transglycosylase (PtTGS1) in P. tricornutum was characterized, which was found to promote chrysolaminain synthesis and reduce lipid synthesis. The continuous accumulation of chrysolaminain was achieved by influencing the shunt of carbon metabolism without affecting the normal physiological state of algal cells, indicating the important role of PtTGS1 gene in chrysolaminain synthesis and carbon shunt pathways.