TY  - JOUR
A1  - Spijkerman, Elly
T1  - The expression of a carbon concentrating mechanism in Chlamydomonas acidophila under variable phosphorus, iron, and CO2 concentrations
JF  - Photosynthesis research
N2  - The CO2 acquisition was analyzed in Chlamydomonas acidophila at pH 2.4 in a range of medium P and Fe concentrations and at high and low CO2 condition. The inorganic carbon concentrating factor (CCF) was related to cellular P quota (Q(p)), maximum CO2-uptake rate by photosynthesis (V-max; O-2), half saturation constant for CO2 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 CO2 grown algae, but maximum Q(p) was 6-fold higher in the low CO2 cells. In high CO2 conditions, the CCF was low, ranging between 0.8 and 3.5. High CCF values up to 9.1 were only observed in CO2-limited cells, but P- and CO2-colimited cells had a low CCF. High CCF did not relate with a low K-0.5 as all CO2-limited cells had a low K-0.5 (<4 mu M CO2). High Ci-pools in cells with high Qp suggested the presence of an active CO2-uptake mechanism. The CCF also increased with increasing V-max; O-2 which reflect an adaptation to the nutrient in highest demand (CO2) under balanced growth conditions. It is proposed that the size of the CCF in C. acidophila is more strongly related to porter density for CO2 uptake (reflected in V-max; O-2) and less- to high-affinity CO2 uptake (low K-0.5) at balanced growth. In addition, high CCF can only be realized with high Q(p).
KW  - C3 photosynthesis
KW  - Micro-algae
KW  - Carbon concentrating mechanism
KW  - Phosphorus limitation
KW  - Iron toxicity
Y1  - 2011
U6  - https://doi.org/10.1007/s11120-010-9607-z
SN  - 0166-8595
VL  - 109
IS  - 1-3
SP  - 179
EP  - 189
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Spijkerman, Elly
A1  - Wacker, Alexander
T1  - Interactions between P-limitation and different C conditions on the fatty acid composition of an extremophile microalga
JF  - Extremophiles : life under extreme conditions
N2  - The extremophilic microalga Chlamydomonas acidophila inhabits very acidic waters (pH 2-3.5), where its growth is often limited by phosphorus (P) or colimited by P and inorganic carbon (CO(2)). Because this alga is a major food source for predators in acidic habitats, we studied its fatty acid content, which reflects their quality as food, grown under a combination of P-limited and different carbon conditions (either mixotrophically with light + glucose or at high or low CO(2), both without glucose). The fatty acid composition largely depended on the cellular P content: stringent P-limited cells had a higher total fatty acid concentration and had a lower percentage of polyunsaturated fatty acids. An additional limitation for CO(2) inhibited this decrease, especially reflected in enhanced concentrations of 18:3(9,12,15) and 16:4(3,7,10,13), resulting in cells relatively rich in polyunsaturated fatty acids under colimiting growth conditions. The percentage of polyunsaturated to total fatty acid content was positively related with maximum photosynthesis under all conditions applied. The two factors, P and CO(2), thus interact in their effect on the fatty acid composition in C. acidophila, and colimited cells P-limited algae can be considered a superior food source for herbivores because of the high total fatty acid content and relative richness in polyunsaturated fatty acids.
KW  - Acidophilic algae
KW  - Cellular P quota
KW  - Chlamydomonas acidophila
KW  - Chlorophyceae
KW  - Colimitation
KW  - CO(2)
KW  - Fatty acid composition
KW  - Food quality
KW  - Glucose
KW  - Mixotrophy
KW  - Photosynthesis
KW  - Phytoplankton
KW  - Phosphorus limitation
Y1  - 2011
U6  - https://doi.org/10.1007/s00792-011-0390-3
SN  - 1431-0651
VL  - 15
IS  - 5
SP  - 597
EP  - 609
PB  - Springer
CY  - Tokyo
ER  -