Recently, the algae and algae biotechnology team at the Institute of Oceanology of the Chinese Academy of Sciences has made progress in the development of astaxanthin resources from red chlorella. It was found that many non-photodependent metabolic pathways, such as anaerobic respiratory glycolysis (EMP), aerobic respiratory tricarboxylic acid cycle (TCA), pentose phosphate pathway (PPP) and mitochondrial respiration alternate oxidase pathway (AOX), have important regulatory effects on astaxanthin synthesis and accumulation. The results were published in three research papers in Bioresource Technology.
Astaxanthin is bright red, has very strong coloring, antioxidant capacity and a variety of biological functions, and has a broad application prospect in the fields of nutrition and health food, medicine and cosmetics. Erythrochlorella is a kind of single-celled green algae rich in astaxanthin, and it is also the best biological resource to produce natural astaxanthin in the world. It was previously believed that astaxanthin biosynthesis was mainly driven by strong light and induced by nutrient deficiency. Most of the studies at home and abroad focused on photodependent anabolic processes (such as photosynthesis, photoprotection and cell growth), and little attention was paid to decomposition and consumptive respiration. Even in recent years, only photodependent photorespiration and chloroplast respiration were involved, while the role of non-photodependent respiratory metabolic pathway in astaxanthin synthesis and accumulation in S. novosa was rarely reported.
The team found and confirmed that multiple non-photodependent respiratory metabolic pathways can effectively regulate astaxanthin synthesis and accumulation. Study found that alternative oxidase way of mitochondrial respiratory activity and red found astaxanthin accumulation was significantly negative correlation, when after the proposed approach is restrained, is closely related to respiration in the middle of the metabolite pyruvic acid and glyceraldehyde 3 phosphoric acid content were significantly improved, at the same time promote the generation of NADPH energy material, and stimulate the accumulation of reactive oxygen species, Thus, astaxanthin synthesis could be promoted. It is suggested that regulation of respiration can promote astaxanthin biosynthesis and accumulation.
In addition, we further confirmed that the TCA cycle, the central hub of energy metabolism in non-photodependent respiration, can provide carbon skeleton for astaxanthin synthesis and promote astaxanthin accumulation in cells mainly by adding intermediate metabolites of respiration. Its regulation mechanism is as follows: Intermediate metabolites fumaric acid can improve the respiratory metabolism of EMP, TCA and the PPP three main ways, makes the pyruvic acid and glyceraldehyde 3 phosphoric acid levels increased significantly, on the one hand, by promoting astaxanthin synthesis precursor of isoamyl ene pyrophosphate, directly promote the synthesis of astaxanthin, on the other hand also promote the synthesis of fatty acids, thus accelerating astaxanthin esterification process, Indirectly promoting astaxanthin synthesis. Oxaloacetate, another metabolite of TCA cycle, can directly promote astaxanthin synthesis by increasing substrate and NADPH levels. Compared with fumaric acid, oxaloacetic acid has a faster and more significant promoting effect, mainly due to its more efficient transmembrane mechanism.
The results improve the red found astaxanthin scale development system of basic theory and development technology, will help improve the bioreactor based on cell cycle regulation and large enclosed light building technologies such as red found development mode, make plant cell photosynthetic plants more efficient operation, promote the industry development level of ascension. At the same time, the research results can be used for reference for the research and resource development of secondary metabolites such as carotene of other microalgae.
