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 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Optimization of Growth and Production of Docosahexaenoic Acid by Schizochytrium limacinum BR2.1.2 Using Plackett-Burman Design and Central Composite Design with Response Sur ผู้เขียน: Lalida Kawsakul,  ดร.วิเชียร ยงมานิตชัย, อาจารย์ , ดร.เดือนรัตน์ ชลอุดมกุล, ผู้ช่วยศาสตราจารย์ สื่อสิ่งพิมพ์:pdf AbstractCulture conditions to maximize growth and the production of docosahexaenoic acid (DHA) by Schizochytrium limacinum BR2.1.2 were optimized using two statistical experimental designs. Three critical factors—temperature, glycerol concentration and peptone concentration—for biomass and DHA production were pre-evaluated by the Plackett-Burman design using low and high levels of the three variables. Low temperature, high glycerol and high peptone concentrations signifi cantly infl uenced both determined parameters. A central composite design and response surface plots were used to optimize the proved signifi cant factors and to generate maximum biomass and DHA production. A second order polynomial equation was generated for dried cell weight (DCW) as YDCW = -83.17811 + 7.77533X1 + 22.49818X2 - 32.53142X3 - 0.12375X1X2 + 0.73850X1X3 + 5.41750X2X3 - 0.20343X1 2 - 1.95541X2 2 - 9.21053X3 2 and that for DHA as YDHA = -21.51223 + 1.32761X1 + 5.27758X2 - 4.69083X3 - 0.01150X1X2 + 0.15400X1X3 + 0.65500X2X3 - 0.036655X1 2 - 0.45401X2 2 - 1.51840X3 2. Five levels of each factor at -1.68, -1, 0, +1 and +1.68 were tested in 17 experiments to validate both models. The P-values were less than 0.05 suggesting that the models were acceptable at this level of signifi cance. The optimal values for temperature, glycerol and peptone concentrations were 18.9 ?C, 6.1% and 0.7%, respectively, and yielded 48.31 g?L-1 of DCW and 5.34 g?L-1 of DHA. Verifi cation of the optimal conditions showed that deviations of DCW and DHA from the experimental data and predicted values were 3–5% and less than 2%, respectively, suggesting that the experimental designs used in this work were effective for growth and DHA production. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Optimization of Lipid Accumulation by Starchless Mutant Chlorella sorokiniana for Biodiesel Production) ผู้เขียน:Watchara Jantasee, ดร.วิเชียร ยงมานิตชัย, อาจารย์, ดร.เดือนรัตน์ ชลอุดมกุล, ผู้ช่วยศาสตราจารย์ สื่อสิ่งพิมพ์:pdf AbstractImprovement of oil accumulation in Chlorella sorokiniana was conducted by ultraviolet mutagenesis. In total, 63 starchless mutants from over 40,000 colonies were screened using an iodine fumigation technique. Eight starchless mutants had relatively high levels of oil accumulation compared to wild type strains. The lipid content of starchless C. sorokiniana DMKU5202-31 increased from 15% to 21.16%. Therefore, this strain was selected for further optimization using a statistical experimental design. Seven factors were screened using a Plackett-Burman design and further optimized using a central composite design (CCD). The Plackett-Burman design presented three significant factors—KNO3, pH and light intensity—that affected biomass and lipid accumulation significantly. CCD was used to optimize the significant factors and indicated that the optimal values for KNO3, pH and light intensity were 0.9 g.L-1, 6.2 and 4,000 lux, respectively. The response surface plots revealed that the maxima for biomass, lipid production and lipid content were 2.58 g.L-1, 1.40 g.L-1 and 54.49%, respectively. Thus, it could be concluded that ultraviolet mutation and the statistical experimental design can be used to improve oil accumulation in C. sorokiniana. After mutation and optimization, strain DMKU5202 had a lipid content increase from 15% to 54.49%. Therefore, these techniques were very efficient for the development of an upstream process for biodiesel production. |
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