Carotenoid and fatty acid metabolism in light-stressed Dunaliella salina.
beta-Carotene is overproduced in the alga Dunaliella salina in response to high light intensities. We have studied the effects of a sudden light increase on carotenoid and fatty acid metabolism using a flat panel photobioreactor that was run in turbidostat mode to ensure a constant light regime throughout the experiments. Upon the shift to an increased light intensity, beta-carotene production commenced immediately. The first 4 h after induction were marked by constant intracellular levels of beta-carotene (2.2 g LCV(-1)), which resulted from identical increases in the production rates of cell volume and beta-carotene. Following this initial phase, beta-carotene productivity continued to increase while the cell volume productivity dropped. As a result, the intracellular beta-carotene concentration increased reaching a maximum of 17 g LCV(-1) after 2 days of light stress. Approximately 1 day before that, the maximum beta-carotene productivity of 30 pg cell(-1) day(-1) (equivalent to 37 mg LRV(-1) day(-1)) was obtained, which was about one order of magnitude larger than the average productivity reported for a commercial beta-carotene production facility, indicating a vast potential for improvement. Furthermore, by studying the light-induced changes in both beta-carotene and fatty acid metabolism, it appeared that carotenoid overproduction was associated with oil globule formation and a decrease in the degree of fatty acid unsaturation. Our results indicate that cellular beta-carotene accumulation in D. salina correlates with accumulation of specific fatty acid species (C16:0 and C18:1) rather than with total fatty acid content.
Wageningen University, Bioprocess Engineering, P.O. Box 8129, 6700 EV Wageningen, the Netherlands. packo.lamers@wur.nl
Packo P
PP
Lamers
Carlien C W
CC
van de Laak
Petrouchka S
PS
Kaasenbrood
Jeroen
J
Lorier
Marcel
M
Janssen
Ric C H
RC
De Vos
Raoul J
RJ
Bino
René H
RH
Wijffels
D018533:Biomass; D002338:Carotenoids / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D008027:Light; D013312:Stress, Physiological; D016823:Volvocida / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects*
D005227:Fatty Acids; D002338:Carotenoids