Metabolic Regulation Of Astaxanthin Biosynthesized In Phaffia Rhodozyma

Astaxanthin is a natural lipid soluble carotenoid of powerful physiological functions. It's named "eatable diamonds" be reason of strong antioxidant and many functions, such as antitumor activities and enhancing immunity. Recently, wide attention which came from a lot of industries was brought to astaxanthin both at home and abroad. As a source of natural astaxanthin, the biosynthesis of astaxanthin in Phaffia rhodozyma is an important way to commercial development of astaxanthin. In order to explore the biosynthesis of astaxanthin, with a view to screening over-producting strains, UV was used to treat Phaffia rhodozyma, and then N-methylmorpholine, lovastatin, isoniazid were selected to screen mutants use as metabolic regulation and control agents, as well as ozone which was used for extracellular inducer in this study. Its effects on growth condition of Phaffia rhodozyma and key steps in the biosynthesis pathway of astaxanthin were also investigated. In view of Phaffia rhodozyma biosynthesized a amount of lipin in the secondary pathway, soybean oil was added to the shake flask and bioreactor as a secondary pathway inhibitor, in order to promote the biosynthesis pathway of astaxanthin. At the same time, the promoter action of oxygen delivery by soybean oil was studied.Experiments have given the following results: the best dose of UV treatment was 5 min, the best screening concentration of cyclase inhibitor N-methylmorpholine was 0.5%, and the best screening concentration of HMG-CoA reductase inhibitor lovastatin was 1×10-4 mol/L. An over-producting mutant LOV4 was obtained, its carotenoid yield reached 15631.88μg/L and carotenoid content reached 1.234746 mg/g dry-cell-weight, which were 28.31% and 36.42% higher than the parent strain G027, respectively. All the seven lovastatin resistant mutants were higher than the parent strain, and carotenoid content were more than 1 mg/g dry-cell-weight. Isoniazid was ruled out the role of the structure analogs. Ozone was verified that it had a pressure on astaxanthin production as an extracellular inducer.After the addition of soybean oil into shake flask and fermentor, carotenoid production were 13.44% and 15.9% higher than the control respectively. Data from oxygen electrode showed that, the addition of soybean oil made dissolved oxygen stable, and 47.05% higher than the control. Because of cheap and easy to use, soybean oil was very significative to use in industrial fermentation as an additive.