Background: Nature astaxanthin is mainly derived from Haematococcus pluvialis. H. pluvialis has four kinds of cell morphology. Based on sequential heterotrophy-dilution-photoinduction (SHDP) technology, photoinduction using non-motile cells as seeds could result in a higher astaxanthin production than that of using brown akinetes as photoinduction seeds. To have a comprehensive understanding of this phenomenon, transcriptome analysis was conducted in this study.
Results: Though most of photosynthesis genes expression were down-regulated during the SHDP culture process. Comparing with the group using brown akinetes as photoinduction seeds, the genes expression involved in astaxanthin biosynthesis, lipid biosynthesis and photosynthesis were up-regulated in the non-motile cells group. Especially, chyb gene improving the conversion of β-carotene into astaxanthin was up-regulated by 2.6-fold. The acaca gene enhancing the carboxylation of acetyl-CoA to malonyl-CoA was up-regulated by 1.4-fold.
Conclusions: Astaxanthin synthesis mechanism of non-motile cells with higher astaxanthin accumulation ability than brown akinetes was attributed to the up-regulation of astaxanthin metabolism, lipid metabolism and photosynthesis-related genes expression. The results are expected to guide the optimization of astaxanthin production in H. pluvialis by improving lipid content or photosynthesis.