Studies On Astaxanthin Production From Jerusalem Artichoke By Fed-batch Fermentation Of Phaffia Rhodozym And Its Application In Cosmetics

Astaxanthin,3,3'-dihydroxy-4,4'-diketo-?,?'-carotene,is a kind of carotenoids.Beacause of the molecular structure of conjugated double bonds and ?-hydroxyketone,it shows superior oxidation resistance,and is widely used in farming,food,cosmetics,pharmaceutical and other industries.Natural astaxanthin is mainly produced by Phaffia rhodozyma and Haematococcus pluvialis.Due to the characteristics of fast growth rate,shorter culture period,simple culture conditions,without light and high-density cultivation,P.rhodozyma quickly becomes the focus of research at home and abroad.However,the low prodctivity of astaxanthin and higher costs seriously limits its industrial development and application.Therefore,this study focuses on improving the production of astaxanthin,reduing the production costs through screening cheap raw materials,optimizing medium and exploring the best fermentation strategy to promote the industrial development of astaxanthin.The effects of sugarcane bagasse hydrolysate and Jerusalem artichoke extract on cell growth and biosynthesis of carotenoids were investigated.The two kinds of materials can be used directly by P.rhodozyma for astaxanthin production,but the lag phase was longer cultured with sugarcane bagasse hydrolysate.In the case of the same sugar consumption,the prouduction of carotenoids cultured with Jerusalem artichoke extract?ca.7.12 mg/L?was about 16.7% higher than those with sugarcane bagasse hydrolysate.Therefore,Jerusalem artichoke extract is more conducive to cell growth and accumulation of carotenoids.In order to further investigate the effect of Jerusalem artichoke extract on cell growth and caroteniods production,the key medium components were optimized through single-factor experimental analysis and the best medium?per liter?consists of sugar concentration of Jerusalem artichoke extract with 30 g total sugar,peptone 8.6 g,KH₂PO₄ 3 g,Na₂HPO₄ 0.5 g,and MgSO₄ 0.5 g.Under the optimal conditions,12.22 g/L of dry cell weight,101.78mg/L of carotenoids production,8.50 mg/g of yield of carotenoids,3.90 mg/g of Yp Caro/s and 0.47 g/g of Yx/s were accumulated by P.rhodozyma in 3 L stirred tank bioreactor.Different feeding strategies including constant,exponential,pH-stat and substrate feedback fermentation were investigated in 3 L stirred tank bioreactor.The results showed that the substrate feedback fermentation?the residual sugar concentration was maintained at the range of 5¹0 g/L?led to the highest dry cell weight of 83.6 g/L and 982.5 mg/L concentration of carotenoids.The YpCaro/x?13.30 mg/g?and YpCaro /s?4.50 mg/g?were 56.5% and 15.4% higher than that with batch culture.Jerusalem artichoke powder can be directly used by P.rhodozyma for astaxanthin production.The key medium components were optimized for astaxanthin production through response surface methodology.The media were made of 34.66 g/L total sugar concentration of Jerusalem artichoke powder and 4.72 of C/N?yeast extract was the best nitrogen source?.When Jerusalem artichoke powder was used as a carbon source,carotenoids concentration of 482.5 mg/L was achieved by continuous feeding Jerusalem artichoke powder.Astaxanthin concentration reached 253.1 mg/L.The YpAst /s and YpCaro /s were 3.08 mg/g and 5.88 mg/g.Due to the superior oxidation resistance,astaxanthin was made into a kind of cosmetic additive: astaxanthin-GTCC?Caprylic/Capric Triglycaride?mixture of a dark red liquid.It has 0.06%?w/w?of astaxanthin and 11.0%?w/w?of protein.The IC50 was 31.79 mg/L.During the four months of storage,total number of bacterial colonies were less than10 cfu/g.Similarly,mold and yeast colonies was less than 10 cfu/g.The dosage recommended in cosmetics was 3.6⁷.2%?w/w?.Storage temperature recommended was relatively low?e.g.4??.The mask of 20 ppm astaxanthin and essence of 40 ppm astaxanthin were prepared through adding the astaxanthin-GTCC mixture into the formulations of mask and essence.The pH of the products are 6⁷.They have good color,even texture and good applicability.During the four months of storage,total number of bacterial colonies was less than 10 cfu/g.Similarly,mold and yeast colonies were less than10cfu/g.The DPPH radical scavenging of astaxanthin mask and astaxanthin essence are 34.38% and 76.29%,respectively.Storage temperature recommended was relatively low?e.g.4??.