• KSBB Journal
• /
• v.15 no.2
• /
• pp.125-133
• /
• 2000

Specific carotenoids and astaxanthin biosynthesis power of Phaffia rhodozyma mutant 876, which was obtained after NTG a and UV treatments, was higher than those of the wild type by 40% and 50%, respectively. The mutant strain did not show t the catabolite repression even at 22% (w/v) glucose concentration. The optimum C{N ratio was 2.0, and the optimum t temperature and initial pH were $22^{\circ}C$ and 6.0, respectively. 80th cell growth and astaxanthin formation decreased drastically a as the fermentation temperature was increased over $22^{\circ}C$, whereas they were comparable in the pH range between 5.0 and 7 7.0. Inoculum size did not affect the final cell density nor the carotenoids biosynthesis, and 3%(v/v) was selected as optimal. H Higher dissolved oxygen concentration facilitated astaxanthin biosynthesis, and aeration rate of 1.0 v/0/m and agitation speed of 400 rpm were selected as optimum. The final cell dens때 of 43.3 g/L and the volumetric astaxanthin and carotenoids concentrations of 110.6 mg/L and 149.4 mg/L, respectively, were obtained. The specific carotenoids concentration was 3.45 m mg{g-yeast(dry). Yx/s and Yp/s values of 0.37 and 1.08 were obtained. The result of this study will provide basic information u useful for mass production of astaxanthin from P. rhodozyma fermentation.

• Korean Journal of Environmental Biology
• /
• v.32 no.1
• /
• pp.58-67
• /
• 2014

The outdoor mass cultivation is not possible for microalgae in Korea all year round, due to cold winter season. It is not easy to maintain proper level of productivity of microalgae even in winter. To prevent a drastic decrease of temperature in a greenhouse, two layers were covered additionally, inside the original plastic layer of the greenhouse. The middle layer was made up of plastic and the inner layer, of non-woven fabric. Acrylic transparent bioreactors were constructed to get more sunlight, not only from the upper side but also from the lateral and bottom directions. In winter at freezing temperatures, six different culture conditions were compared in the triply covered, insulated greenhouse. Wastewater after anaerobic digestion was used for the cultivation of microalgae to minimize the production cost. Water temperature in the bioreactors remained above $10^{\circ}C$ on average, even without any external heating system, proving that the triple-layered greenhouse is effective in keeping heat. Algal biomass reached to 0.37g $L^{-1}$ with the highest temperature, in the experimental group of light-reflection board at the bottom, with nitrogen and phosphorus removal rate of 92% and 99%, respectively. When fatty acid composition was analyzed using gas-chromatography, linoleate (C18 : 3n3) occupied the highest proportion up to 61%, in the all experiment groups. Chemical oxygen demand (COD), however, did not decrease during the cultivation, but rather increased. Although the algal biomass productivity was not comparable to warm seasons, it was possible to maintain water temperature for algae cultivation even in the coldest season, at the minimum cost.