| Induction of the carbon concentrating mechanism (CCM) was characterized during the acclimation of 5% CO2-grown Chlamydomonas reinhardtii (2137 mt+) and Chlorella kessleri (UTEX 1808) cells to well-defined dissolved inorganic carbon (DIC) limited conditions. The CCM components investigated in both cell types were active HCO3 - and CO2 uptake. The maximum rate of photosynthesis (Pmax) was similar for high- and low-CO2 grown cells of Chlorella kessleri, but the apparent whole cell affinity for DIC and CO2 (K1/2) of high CO2-grown cells was about 30-fold greater than that in air-grown cells, which indicates a lower affinity for DIC and CO2. Bicarbonate and CO2 transport were induced after 5.5 h in Chlorella kessleri cells acclimating to CO2-free air and air, in the presence and absence of 21% O2. This indicates that a change in the CO 2/O2 ratio in the acclimating medium does not trigger induction of DIC transport. (Abstract shortened by UMI.)... |
