Thoms, S. Alfred-Wegener-Institut, sthoms@awi-bremerhaven.de
Pahlow, M. Alfred-Wegener-Institut, mpahlow@awi-bremerhaven.de

 
A 4 COMPARTMENT MODEL OF PHYTOPLANKTON CHLOROPLASTS FOR THE CARBON CONCENTRATING MECHANISM
 
The common observation that the affinity of most phytoplankton for carbon dioxide is much higher than that of RuBisCO has led to proposing carbon concentrating mechanisms (CCMs). While several algae can utilise bicarbonate, which is converted to carbon dioxide via carbonic anhydrase (CA), others have been shown to rely solely on carbon dioxide uptake. Ideas put forward to explain algal CCMs include lowering external pH and extracellular CA, active uptake od carbon dioxide and bicarbonate, as well as processes within the chloroplast. Recently, a role of low thylakoid lumen pH in combination with intrathylakoidal CA was suggested; the presence of CA in the thylakoid lumen and the chloroplast envelope was demonstrated. Here we present a detailed mathematical model based on chloroplast fine structure, membrane permeability, and the distribution of pH and CA. Fluxes and reactions within and between the envelope, girdle lamella, stroma, and thylakoids are incorporated. The model generates near saturating carbon dioxide concentration for RuBisCO in the stroma and is consistent with current understanding of carbon-isotope fractionation.
 
Day: Monday, Feb. 1
Time: 03:45 - 04:00pm
Location: Eldorado Hotel
 
Code: SS32MO0345E