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Production of phytoene by herbicide‐treated microalgae Dunaliella bardawil in two‐phase systems
Author(s) -
León Rosa,
Vila Marta,
Hernánz Dolores,
Vílchez Carlos
Publication year - 2005
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.20660
Subject(s) - phytoene , dunaliella , phytoene desaturase , carotenoid , biochemistry , xanthophyll , fluridone , chemistry , biology , lutein , botany , food science , biosynthesis , algae , lycopene , enzyme
In the present study we have optimized the concentration of the bleaching herbicide norflurazon to obtain Dunaliella bardawil cells able to accumulate phytoene without losing viability. The highest concentration of phytoene 10.4 g/gChl was obtained for a concentration of norflurazon of 10 µg/mL. Norflurazon‐treated Dunaliella bardawil cells are able to accumulate high concentrations of phytoene if the carotenogenic pathway is stimulated, but the lack of colored carotenoids make these cells particularly sensitive to high light intensities and to UVB radiation, so other stimuli, such as nitrogen starvation, have to be used to force the accumulation of phytoene. Detailed time‐course evolution of the carotenoids lutein, violaxanthin, zeaxanthin, phytene and β‐carotene and the photosynthetic pigment chlorophyll was followed upon transfer of Dunaliella bardawil cells to nitrogen starvation in presence and absence of norflurazon. The combined use of the carotenogenic pathway inhibitor norflurazon and biphasic aqueous/organic systems to force the excretion of phytoene into the culture medium has been investigated. Cells cultured in the biphasic system were viable and able to produce phytoene during 3 days. Futhermore the productivity increased from 0.14 g/gChl · h in the aqueous culture to 0.18 g/gChl · h in the biphasic system. About 15% of the total phytoene produced by Dunaliella bardawil was excreted and immediately partionated into the organic phase. The concentration of phytoene in the decane phase was 2.05 g/gChl after 72 h, this means that about 47 g of phytoene per litre of culture were in the organic phase. © 2005 Wiley Periodicals, Inc.