Effect of light intensity on β-carotene production and extraction by Dunaliella salina in two-phase bioreactors
ABSTRACT 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.
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- "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. "
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).Journal of Food Science and Technology -Mysore- 12/2013; 50(6):1130-6. DOI:10.1007/s13197-011-0429-6 · 2.02 Impact Factor
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- "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). "
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.Biotechnology and Bioengineering 09/2010; 107(1):65-75. DOI:10.1002/bit.22774 · 4.16 Impact Factor
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ABSTRACT: β-carotene is the main source of pro-vitamin A and is widely used as a food colorant, with a global market estimated to surpass USD 280 million in 2015. The majority of the β-carotene commercialized in the world is obtained by chemical synthesis from β-ionone. Alternatively, the production of β-carotene can be reached on a biotechnological basis, using filamentous fungi, bacteria, microalgae, and yeasts as producers, or even by extraction from vegetable sources, such as oil palm (Elaeis guineensis) and buriti (Mauritia vinifera). The present review is focused on the current technologies for β-carotene production and presents an overview of new tendencies regarding the carotenoids extraction from microbial and vegetal feedstocks, as well as processes for their concentration. Keywordsβ-carotene– Dunaliella –Palm– Blakeslea –Enzyme extractionFood and Bioprocess Technology 07/2011; 4(5):693-701. DOI:10.1007/s11947-011-0545-3 · 3.13 Impact Factor