Effect of light intensity on β-carotene production and extraction by Dunaliella salina in two-phase bioreactors
Food and Bioprocess Engineering Group, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands. Biomolecular Engineering
(Impact Factor: 3.17).
08/2003; 20(4-6):171-5. DOI: 10.1016/S1389-0344(03)00046-7
Application of two-phase bioreactors is a useful technique for improvement of the productivity of fermentations. Fermentative extraction of the products in situ is performed in this technique. The effect of light intensity on the extraction of beta-carotene from Dunaliella salina, in the fermentative extraction, has been investigated. Three different average light exposures were applied: 1.5 x 10(-8) (low), 2.7 x 10(-8) (intermediate) and 4.5 x 10(-8) (high) micromol s(-1) per cell. Results show that beta-carotene content of the cells increases by increasing the light exposure. Increase in the beta-carotene content of the cells is not necessarily coupled with an increase in the volumetric production of beta-carotene. Final volumetric production is about the same for the three bioreactors. beta-Carotene extraction rate is enhanced by the increase in the light exposure. The results suggest that extraction rate is related to beta-carotene content of the cells and is not essentially related to the volumetric production of beta-carotene. Although the effectiveness of extraction with respect to the light input is comparable for all light intensities applied, increasing the light input per cell leads to a higher volumetric extraction rate. Moreover, extracted beta-carotene stays very pure even so the extraction increased by the increase of light intensity.
Available from: Kavitha M.D.
- "Carotenoid biosynthesis is governed by the level and activity of carotenoid biosynthesis enzymes. Dunaliella when exposed to stress conditions such as salinity (Fazeli et al. 2006), high light (Hejazi and Wijffels 2003), or nutrient limitation (Raja et al. 2007), two stereoisomers of βcarotene , all-trans and 9-cis may be accumulated reaching up to 10% of the dry cell weight (Ben-amotz et al. 1982). Metabolic inhibitors like glyphosate (amino acid biosynthesis inhibitor), glufosinate ammonium which is also called as basta (glutamine synthase inhibitor in nitrogen metabolism pathway), DCMU (photosynthetic inhibitor), DPA (inhibitor of β-carotene C-4 oxygenase), nicotine (lycopene cyclase inhibitor) and caffeine (cytokinesis inhibitor) were evaluated to study their effect on growth, carotenoid profile and fatty acid profile of the marine micro alga D. bardawil under two different light intensities. "
[Show abstract] [Hide abstract]
ABSTRACT: Dunaliella bardawil, a green alga accumulates high amount of β-carotene under stress conditions. This organism has been exploited for β-carotene at industrial scale. In the present work, various metabolic inhibitors like diphenylamine (DPA), nicotine, basta, glyphosate, DCMU [3-(3',4'-dichlophenyl)-1,1-dimethylurea] and caffeine were used in autotrophic medium, to understand their influence on carotenoid biosynthesis. The results indicated that these metabolic inhibitors influenced the production of carotenoids like wise, DPA and basta increased the contents of β-carotene (1.7 fold), glyphosate and DCMU for lutein (2.4 and 2 fold) caffeine for biomass yields (1.1 fold), while nicotine decreased the biomass yield (3.6 fold), β-carotene (2 fold) and lutein (10.5 fold).
Available from: umn.edu
- "Dunaliella has been found to be one of the richest natural sources of b-carotene (Hejazi and Wijffels, 2003; Raja et al., 2007; Zhu and Jiang, 2008). Under suitable conditions, Dunaliella can accumulate up to 10% of the dry cell weight of b-carotene (Loeblich, 1974; Jin and Melis, 2003). "
[Show abstract] [Hide abstract]
ABSTRACT: The objective of this work was to quantify the kinetic behavior of Dunaliella primolecta (D. primolecta) subjected to controlled fluid flow under laboratory conditions. In situ velocities of D. primolecta were quantified by micron-resolution particle image velocimetry and particle tracking velocimetry. Experiments were performed under a range of velocity gradients and corresponding energy dissipation levels at microscopic scales similar to the energy dissipation levels of natural aquatic ecosystems. An average swimming velocity of D. primolecta in a stagnant fluid was 41 microm/s without a preferential flow direction. In a moving fluid, the sample population velocities of D. primolecta follow a log-normal distribution. The variability of sample population velocities was maximal at the highest fluid flow velocity in the channel. Local fluid velocity gradients inhibited the accrual of D. primolecta by twofold 5 days after the initiation of the experiment in comparison to the non-moving fluid control experiment.
Available from: Yuehui Zhu
- "Dunaliella salina cells(1/2 SW), purchased from the Institute of Hydrobiology, Chinese Academy of Sciences, were grown according to the methods of Hejazi and Wijffels (2003) with minor modification (Zhu et al., 2007). The medium was sterilized at 121ºC for 30 min before inoculation. "
[Show abstract] [Hide abstract]
ABSTRACT: Carbon tetrachloride (CCl(4)), a water disinfection by-product, at low environmentally relevant concentrations exerts adverse effects on mammals. The unicellular microalga Dunaliella salina possessing a remarkable degree of environmental adaptation was selected as test organism to investigate low-level exposure to CCl(4). With incubation with less than 0.13% CCl(4), algae responses were similar to control as evidenced by cell growth and levels of beta-carotene, a marker of adaptation. The maximal concentration of CCl(4) that D. salina could tolerate was 0.2%. Algae incubated with more than 0.32% CCl(4) showed decreased growth and reduced beta-carotene levels, which were nondetected after a few days. However, after 98 d, D. salina seemed to revive as evidenced by growth and returned to the biomass similar to control in another 25 d. Randomly amplified polymorphic DNA (RAPD) method was used to compare the genomic DNA difference between control and recovered cells. Polymorphic and repeatable RAPD bands indicated that chronic effects of CCl(4) to D. salina led generation of altered genomic DNA, which may enable the microalga to adapt to survival in an apparently toxic substance environment.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.