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Physiology and xanthophyll cycle activity of Nannochloropsis gaditana
Author(s) -
Gentile MariePierre,
Blanch Harvey W.
Publication year - 2001
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.1158
Subject(s) - violaxanthin , antheraxanthin , xanthophyll , zeaxanthin , biology , chemistry , botany , chlorophyll a , lutein , photosynthesis , carotenoid
The physiology of the violaxanthin‐producing microalga Nannochloropsis gaditana is examined and the effect of environmental factors on the growth and cellular pigment content investigated in batch and continuous cultures. N. gaditana is slow‐growing, with a maximum specific growth rate of 0.56 day −1 at 23°C. The xanthophyll cycle is present in this strain, but has a much lower activity than in higher plants and other species of Nannochloropsis . At 30°C, under high light (1500 μmol photons m −2 s −1 ), 33% of the violaxanthin pool was de‐epoxidated to antheraxanthin (76%) and zeaxanthin (24%) over 60 min. Addition of iodoacetamide dramatically affected the xanthophyll cycle activity: 50% of the violaxanthin was replaced by zeaxanthin (90%) within 30 min. This was attributed to an increase in membrane fluidity following iodoacetamide addition, resulting in a larger pool of violaxanthin available for conversion. Batch culture studies showed that a decrease in irradiance (from 880 to 70 μmol photons m −2 s −1 ) can increase chlorophyll a and violaxanthin content by as much as 80% and 60%, respectively. Continuous cultures indicated that violaxanthin is a growth‐rate‐dependent product, but the violaxanthin content is less affected by dilution rate (in the range 0.12 to 0.72 day −1 ) and pH (6.8 to 7.8) than chlorophyll a. The optimum conditions for growth and violaxanthin production in continuous culture were found to occur at a dilution rate of 0.48 day −1 , a temperature of between 24°C and 26°C, and pH in the range 7.1 to 7.3. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 1–12, 2001.