242 W. VISHNIAC AND G. H. REAZIN, JR. 



Discussion 



Frenkel : Is the assumption of the ratio of isopropanol used to CO^ fixed de- 

 pendent upon the product that is formed? 



Vishniac : If you assume that carbohydrate was formed, then two moles of iso- 

 propyl alcohol would have to be oxidized to acetone to fix CO2. If the end prod- 

 ucts are different then the ratio of isopropyl alcohol used to CO2 fixed will change, 

 but it would not change the general interpretation of this experiment. 



Aronoff : Is it not possible that, even with glucose, you had CO2 reduction? 



Vishniac: Yes. We can assume, for instance, that all the organic carbon is 

 formed by CO2 fixation, but this goes along with oxidation of the glucose. 



Aronoff: And having been at Brookhaven, were you not testing this with 

 isotopes? 



Vishniac : No, because I think that as far as these data are concerned we are 

 dealing with net results and are not at a point where isotopes would help in the 

 interpretation. 



Frenkel : I was wondering if Dr. Gaffron wants to make some remarks about 

 his experiments on the effect of glucose on photoreduction. 



Gaffron: Glucose or glucose derivatives are capable of replacing molecular 

 hjrdrogen as hydrogen donor during photoreduction in Scenedesmus. I think we 

 have experiments which show that Chlorella might be trained to do this trick too, 

 though for lack of a hydrogenase it cannot utilize free hydrogen. However, as 

 3^et I do not have a mass spectrograph. So we expect from Dr. Brown the next 

 data on this. 



References 



1. Priugsheim, E. G., Quart. J. Microscop. Soc, 93, 71 (1952). 



2. Hutner, S. H., Provasoli, L., and FiKus, J., Ann. N.Y. Acad. Set., 66, 852 



(1953). 



3. Meyers, J., personal communication. 



4. Reazin, G. H., Jr., Am. J. Botany, 4I, 771 (1954). 



5. Weis, D., Thesis, Yale University, New Haven, 1955. 



6. Gaffron, H., Atn. J. Botany, 27, 273 (1940). 



7. Frenkel, A. W., and Rieger, C., Nature, 167, 1030 (1951). 



8. Benson, A. A., et al., in Photosynthesis in Plants, J. Franck and W. E. Loomis, 



eds., p. 381. Iowa State College Press, Ames, 1949. 



9. Foster, J., /. BacterioL, 47, 355 (1944). 



10. Schatz, A., /. Gen. MicroUoL, 6, 329 (1952). 



