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J.-F. Cornet et al.
phycocyanins and other cell mass components (carbohydrates, nucleic acids,
lipids) and absorption and scattering coefficients depending on the phycocyanin
content of the cells. The model is able to represent the consumption of pigments
under nitrogen or sulphur deprivation and relative accumulation of glycogen.
The effect of phosphate deprivation is less well understood, probably due to
large intracellular reserve pools.
Very little reliable experimental data is available for studying the influence of
CO2-HC03-CO~- limitation. The qualitative presentation reported here
shows that this complex problem involves physiological metabolic regulation of
the Calvin cycle, gas-liquid transfer characterization inside the medium, chemical equilibria between the different forms of dissolved carbon, strongly dependent on the pH value and, to a lesser extent, total ionic strength.
Biochemically structured models are promising tools for characterizing the
orientations of the metabolism by the determination of the P/2e- ratio. The
theoretical calculations, which involve the theory of linear energy converters,
enable the effects of the limitations to be satisfactorily interpreted at a metabolic
level. As predicted by the theory, the macroscopic entropy and enthalpy balances established for the growth of Spirulina platensis show that the global
thermodynamic efficiency for light energy conversion decreases when light
energy availability in the medium is increased, which corresponds to a highest
value of 15% for low energy inputs. This clearly demonstrates the promising
features of such analysis for the determination of the yields and of the reaction
rates during growth and/or metabolite production processes of photosynthetic
micro-organisms.
Acknowledgements. The authors are grateful to the European Space Agency (ESA) for their financial
support through the MELiSSA project, and the Centre National d'Etudes Spatiales (CNES France).
Some experimental determinations were performed at the CNRS, Laboratoire de Biochimie
Fonctionelle des Membranes V6g6tales (Gif sur Yvette-France). We are especially indebted to G.
Dubertret and A. Tremoli6res.
8 References
1. Roels JA (1983) Energetics and kinetics in biotechnology. Elsevier Biomedical Press
2. Van Eykelenburg C (1979) Antonie van Leeuwenhoek 45:369
3. Ciferri O (1983) Microbiol Rev 47:551
4. Clement G (1975) Nutr Rev Alim 29:477
5. Fox RD (1986) Algoculture: la Spirulina, un espoir pour le monde de la faim. Edisud
6. Sekharam KM, Venkataraman LV, Salimath PV (1989) Food Chemistry 31:85
7. Cornet J-F (1992) Thesis n ~ 1989, University of Paris XI, Orsay, France
8. Vincenzini M, Sili C, De Philippis R, Ena A, Materassi R (1990) J Bacteriol 172:2791
9. Filali-Mouhim R, Cornet J-F, Fontaine T, Fournet B, Dubertret G (1993) Biotech Letters 15:
567
10. Nicholls DG, Ferguson SJ (1992) Bioenergetics 2. Academic Press
11. Miller AG, Colman B (1980) J. Bacteriol 143:1253
12. Coleman JR, Colman B (1981) Plant Physiol 67:917
J.-F. Cornet et al.
phycocyanins and other cell mass components (carbohydrates, nucleic acids,
lipids) and absorption and scattering coefficients depending on the phycocyanin
content of the cells. The model is able to represent the consumption of pigments
under nitrogen or sulphur deprivation and relative accumulation of glycogen.
The effect of phosphate deprivation is less well understood, probably due to
large intracellular reserve pools.
Very little reliable experimental data is available for studying the influence of
CO2-HC03-CO~- limitation. The qualitative presentation reported here
shows that this complex problem involves physiological metabolic regulation of
the Calvin cycle, gas-liquid transfer characterization inside the medium, chemical equilibria between the different forms of dissolved carbon, strongly dependent on the pH value and, to a lesser extent, total ionic strength.
Biochemically structured models are promising tools for characterizing the
orientations of the metabolism by the determination of the P/2e- ratio. The
theoretical calculations, which involve the theory of linear energy converters,
enable the effects of the limitations to be satisfactorily interpreted at a metabolic
level. As predicted by the theory, the macroscopic entropy and enthalpy balances established for the growth of Spirulina platensis show that the global
thermodynamic efficiency for light energy conversion decreases when light
energy availability in the medium is increased, which corresponds to a highest
value of 15% for low energy inputs. This clearly demonstrates the promising
features of such analysis for the determination of the yields and of the reaction
rates during growth and/or metabolite production processes of photosynthetic
micro-organisms.
Acknowledgements. The authors are grateful to the European Space Agency (ESA) for their financial
support through the MELiSSA project, and the Centre National d'Etudes Spatiales (CNES France).
Some experimental determinations were performed at the CNRS, Laboratoire de Biochimie
Fonctionelle des Membranes V6g6tales (Gif sur Yvette-France). We are especially indebted to G.
Dubertret and A. Tremoli6res.
8 References
1. Roels JA (1983) Energetics and kinetics in biotechnology. Elsevier Biomedical Press
2. Van Eykelenburg C (1979) Antonie van Leeuwenhoek 45:369
3. Ciferri O (1983) Microbiol Rev 47:551
4. Clement G (1975) Nutr Rev Alim 29:477
5. Fox RD (1986) Algoculture: la Spirulina, un espoir pour le monde de la faim. Edisud
6. Sekharam KM, Venkataraman LV, Salimath PV (1989) Food Chemistry 31:85
7. Cornet J-F (1992) Thesis n ~ 1989, University of Paris XI, Orsay, France
8. Vincenzini M, Sili C, De Philippis R, Ena A, Materassi R (1990) J Bacteriol 172:2791
9. Filali-Mouhim R, Cornet J-F, Fontaine T, Fournet B, Dubertret G (1993) Biotech Letters 15:
567
10. Nicholls DG, Ferguson SJ (1992) Bioenergetics 2. Academic Press
11. Miller AG, Colman B (1980) J. Bacteriol 143:1253
12. Coleman JR, Colman B (1981) Plant Physiol 67:917