The expression of a carbon concentrating mechanism in Chlamydomonas acidophila under variable phosphorus, iron, and CO2 concentrations

Abstract

The CO(2) acquisition was analyzed in Chlamydomonas acidophila at pH 2.4 in a range of medium P and Fe concentrations and at high and low CO(2) condition. The inorganic carbon concentrating factor (CCF) was related to cellular P quota (Q(p)), maximum CO(2)-uptake rate by photosynthesis (V(max,O2)), half saturation constant for CO(2) uptake (K(0.5)), and medium Fe concentration. There was no effect of the medium Fe concentration on the CCF. The CCF increased with increasing Q(p) in both high and low CO(2) grown algae, but maximum Q(p) was 6-fold higher in the low CO(2) cells. In high CO(2) conditions, the CCF was low, ranging between 0.8 and 3.5. High CCF values up to 9.1 were only observed in CO(2)-limited cells, but P- and CO(2)-colimited cells had a low CCF. High CCF did not relate with a low K(0.5) as all CO(2)-limited cells had a low K(0.5) (<4 μM CO(2)). High C(i)-pools in cells with high Q(p) suggested the presence of an active CO(2)-uptake mechanism. The CCF also increased with increasing V(max,O2) which reflect an adaptation to the nutrient in highest demand (CO(2)) under balanced growth conditions. It is proposed that the size of the CCF in C. acidophila is more strongly related to porter density for CO(2) uptake (reflected in V(max,O2)) and less- to high-affinity CO(2) uptake (low K(0.5)) at balanced growth. In addition, high CCF can only be realized with high Q(p).

Systems Analysis of the Response of Photosynthesis, Metabolism, and Growth to an Increase in Irradiance in the Photosynthetic Model OrganismChlamydomonas reinhardtii

“…As these genes are induced by low CO 2 (Burow et al, 1996;Van et al, 2001;Pollock et al, 2004), they have been proposed to be part of the inorganic carbon concentrating mechanism. High light may induce LCI1 because the resulting increase in the rate of photosynthesis leads to a temporary decrease in the internal CO 2 concentration, which induces genes involved in the carbon concentrating mechanism (McGinn et al, 2003;Spijkerman, 2011). Another strongly induced transcript was NRX3, which showed a 39-fold increase 40 min after the light shift.…”

Algal evolution in relation to atmospheric CO 2 : carboxylases, carbon-concentrating mechanisms and carbon oxidation cycles

“…Modified from [10]. Further details and references are given in the text and in [10][11][12]101,105,106,110,[112][113][114][115][116][117][118][119][120]. Predicted resource costs of synthesizing and operating a photosynthetic apparatus using a CCM relative to one relying on entry of CO 2 by diffusion [66,[68][69][70][71]73,91,105,121] Pleistocene, they would have had to have survived intervening period(s) of higher CO 2 and higher temperatures.…”

CO 2 concentrating mechanisms and environmental change

“…The work of García et al (2013) can apparently be added to the three examples in Table 4 of increased CO 2 affinity under phosphorus limitation. The data of Spijkerman (2011) and Spijkerman et al (2011) were not used here, since their measure of CCF used DIC rather than CO 2 , which makes a very large difference for the acidophilic Chlamydomonas species examined, A data set on Pseudo-nitzschia multiseries that permits calculation of the phosphorus use efficiency (PUE; mol C accumulated. mol −1 cell P s −1 ) of algal growth as a function of CO 2 availability, as was performed for N, shows that P-replete cells at low CO 2 (22 Pa) and high CO 2 (74 Pa) have PUEs of 1910 × 10 −6 and 2750.10 −6 mol C accumulated mol −1 P s −1 , respectively, and P-limited cells at low CO 2 (22 Pa) and high CO 2 (74 Pa) have PUEs of 455 × 10 −6 and 974 × 10 −6 mol C accumulated mol −1 P s −1 , respectively (Sun et al, 2011).…”