title: Optimization of biomass, vitamins, and carotenoid yield on light energy in a flat-panel reactor using the A-stat technique.
abstract: Acceleration-stat (A-stat) cultivations in which the dilution rate is continuously changed at a constant acceleration rate, leading to different average light intensities inside the photobioreactor, can supply more information and reduce experimental time compared with chemostat cultivations. The A-stat was used to optimize the biomass and product yield of continuous cultures of the microalgae D. tertiolecta in a flat-panel reactor. In this study, four different accelerations were studied, a pseudo steady state was maintained at acceleration rates of 0.00016 and 0.00029 h(-2) and results were similar to those of the chemostat. An increase in the acceleration rate led to an increase in the deviation between results obtained in the A-stat and in the chemostats. We concluded that it is advantageous to use the A-stat instead of chemostats to determine culture characteristics and optimize a specific photobioreactor. The effect of average light intensity inside the photobioreactor on the production of vitamins C and E, lutein, and beta-carotene was studied using the A-stat. The highest concentrations of these products were 3.48 +/- 0.46, 0.33 +/- 0.06, 5.65 +/- 0.24, and 2.36 +/- 0.38 mg g(-1), respectively. These results were obtained at different average light intensities, showing the importance of optimizing each product on light intensity.
authors.affiliation: Food and Bioprocess Engineering Group, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands. maria.barbosa@wur.nl
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Barbosa
authors.forename: Jan Willem
authors.initials: JW
authors.lastname: Zijffers
authors.forename: Adrian
authors.initials: A
authors.lastname: Nisworo
authors.forename: Woulter
authors.initials: W
authors.lastname: Vaes
authors.forename: Jan
authors.initials: J
authors.lastname: van Schoonhoven
authors.forename: René H
authors.initials: RH
authors.lastname: Wijffels
mesh_terms: D001205:Ascorbic Acid / Q000096:biosynthesis*; D019149:Bioreactors / Q000382:microbiology*; D002338:Carotenoids / Q000096:biosynthesis*; D018929:Cell Culture Techniques / Q000379:methods*; D049109:Cell Proliferation / Q000528:radiation effects; D000460:Chlorophyta / Q000502:physiology* / Q000528:radiation effects; D003198:Computer Simulation; D004735:Energy Transfer / Q000502:physiology / Q000528:radiation effects; D017022:Flow Injection Analysis; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D014810:Vitamin E / Q000096:biosynthesis*
chemical_list: D014810:Vitamin E; D002338:Carotenoids; D001205:Ascorbic Acid