Abstract
An equation has been developed incorporating whole-cell rate constants for CO2 and HCO3- that describes accurately photosynthesis (Phs) in suspensions of unicellular algae at low dissolved inorganic carbon. At pH 8.0 the concentration of CO2 available to the algal cells depends on the rate of supply from, and the loss to, HCO3- and the rate of use by the cells. At elevated cell densities (>30 mg chlorophyll [Chl] L-1), at which CO2 use by the cells is high, the slope of a graph of absolute Phs versus Chl concentration approaches the rate of Phs on a milligram of Chl basis because of HCO3- use alone. The slope of a graph of Phs versus HCO3- will be the rate constant for HCO3-, and for Chlorella saccharophila it was 0.16 L mg-1 Chl h-1. The difference between the constants for dissolved inorganic carbon (measured in cells with external carbonic anhydrase) and HCO3-1 is the constant for CO2, which was 26 L mg-1 Chl h-1. This difference causes the half-saturation constant for Phs to increase 5- to 6-fold at high cell densities. The increase in CO2 use as a result of external carbonic anhydrase is described mathematically as a function of cell density.
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Selected References
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- Espie G. S., Colman B. Inorganic Carbon Uptake during Photosynthesis : I. A Theoretical Analysis Using the Isotopic Disequilibrium Technique. Plant Physiol. 1986 Apr;80(4):863–869. doi: 10.1104/pp.80.4.863. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mayo W. P., Elrifi I. R., Turpin D. H. The Relationship between Ribulose Bisphosphate Concentration, Dissolved Inorganic Carbon (DIC) Transport and DIC-Limited Photosynthesis in the Cyanobacterium Synechococcus leopoliensis Grown at Different Concentrations of Inorganic Carbon. Plant Physiol. 1989 Jun;90(2):720–727. doi: 10.1104/pp.90.2.720. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Miller A. G., Colman B. Evidence for HCO(3) Transport by the Blue-Green Alga (Cyanobacterium) Coccochloris peniocystis. Plant Physiol. 1980 Feb;65(2):397–402. doi: 10.1104/pp.65.2.397. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Moroney J. V., Husic H. D., Tolbert N. E. Effect of Carbonic Anhydrase Inhibitors on Inorganic Carbon Accumulation by Chlamydomonas reinhardtii. Plant Physiol. 1985 Sep;79(1):177–183. doi: 10.1104/pp.79.1.177. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Price G. D., Badger M. R. Ethoxyzolamide Inhibition of CO(2)-Dependent Photosynthesis in the Cyanobacterium Synechococcus PCC7942. Plant Physiol. 1989 Jan;89(1):44–50. doi: 10.1104/pp.89.1.44. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shelp B. J., Canvin D. T. Utilization of Exogenous Inorganic Carbon Species in Photosynthesis by Chlorella pyrenoidosa. Plant Physiol. 1980 May;65(5):774–779. doi: 10.1104/pp.65.5.774. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sültemeyer D. F., Miller A. G., Espie G. S., Fock H. P., Canvin D. T. Active CO(2) Transport by the Green Alga Chlamydomonas reinhardtii. Plant Physiol. 1989 Apr;89(4):1213–1219. doi: 10.1104/pp.89.4.1213. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thielmann J., Tolbert N. E., Goyal A., Senger H. Two Systems for Concentrating CO(2) and Bicarbonate during Photosynthesis by Scenedesmus. Plant Physiol. 1990 Mar;92(3):622–629. doi: 10.1104/pp.92.3.622. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Williams T. G., Colman B. Identification of Distinct Internal and External Isozymes of Carbonic Anhydrase in Chlorella saccharophila. Plant Physiol. 1993 Nov;103(3):943–948. doi: 10.1104/pp.103.3.943. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Williams T. G., Turpin D. H. The Role of External Carbonic Anhydrase in Inorganic Carbon Acquisition by Chlamydomonas reinhardii at Alkaline pH. Plant Physiol. 1987 Jan;83(1):92–96. doi: 10.1104/pp.83.1.92. [DOI] [PMC free article] [PubMed] [Google Scholar]