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Effect of O 2 :CO 2 ratio on the primary metabolism of Chlamydomonas reinhardtii
Author(s) -
Kliphuis Anna M.J.,
Martens Dirk E.,
Janssen Marcel,
Wijffels René H.
Publication year - 2011
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.23194
Subject(s) - photorespiration , photobioreactor , rubisco , chlamydomonas reinhardtii , photosynthesis , biomass (ecology) , carbon dioxide , yield (engineering) , oxygenase , chemistry , botany , biology , biochemistry , agronomy , materials science , gene , mutant , metallurgy , organic chemistry
High oxygen:carbon dioxide ratios may have a negative effect on growth and productivity of microalgae. To investigate the effect of O 2 and CO 2 concentrations and the ratio between these on the metabolism of Chlamydomonas reinhardtii we performed turbidostat experiments at different O 2 :CO 2 ratios. These experiments showed that elevated O 2 concentrations and the corresponding increase in the ratio of O 2 :CO 2 common in photobioreactors led to a reduction of growth and biomass yield on light with 20–30%. This is most probably related to the oxygenase activity of Rubisco and the resulting process of photorespiration. Using metabolic flux modeling with measured rates for each experiment we were able to quantify the ratio of the oxygenase reaction to the carboxylase reaction of Rubisco and could demonstrate that photorespiration indeed can cause the reduction in biomass yield on light. The calculated ratio of the oxygenase reaction to the carboxylase reaction was 16.6% and 20.5% for air with 2% CO 2 and 1% CO 2 , respectively. Thus photorespiration has a significant impact on the biomass yield on light already at conditions common in photobioreactors (air with 2% CO 2 ). Biotechnol. Bioeng. 2011;108: 2390–2402. © 2011 Wiley Periodicals, Inc.