The best figure for CO2 fixation  in PNS was around 15 (1/0.065) phot/mol. This is the initial slope of a light response curve. I guess this depends on open flow electron transport. I do not know how a cyclic feedback and CO2 transport are so expensive , relative to H2

Dear Guido,

          In back-of-envelope calculations I guessed it must be about 12-16 even though in real situations it is probably a lot higher.

          Your figure of 15 is much appreciated but where did you get it?  Cannot find it in Kozlova paper.  I suspect it comes from Godel's figure in a book edited by Clayton, the problem is I cannot obtain the book and chapter in Thailand.

Yes old scrap from light cirves but comparing  curves is not theory and they came from different experiments. Conditioning may well alterate membrane porosity

Raymond J Ritchie Did you ever found a value for this question? I'm also looking into it, and I don't understand where this 15 photons/molecule of CO2 is coming from.

Thanks,

Janne

The figure roughly calculated in our paper Larkum, Ritchie and Raven 2018 is around 16. This based on how much ATP & NADPH2 is needed to fix CO2 and that PS bacteria have only one photosystem and the roundabout way PS bacteria have to make the ATP + plus NADPH2 required.

The measurements needed have largely not been seriously attempted for about 50y.