ISSN:
1432-072X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary 1. The purple sulphur bacteria are able to develop in media containing only one simple, nitrogen-free organic compound, in the absence of oxidizable sulphur compounds. 2. Radiant energy is indispensable for development in these media. 3. A quantitative chemical investigation has been carried out of the metabolism in cultures containing lactate, pyruvate, acetate, succinate, malate or butyrate as the organic substrate. 4. In these cultures practically no metabolic products other than relatively small amounts of CO2 have been detected; in the butyrate cultures CO2 is taken up instead of being formed. 5. By determining the carbon content of the bacterial substance synthesized in the cultures, it has been shown that in all probability the substrate is completely converted into cell material and CO2, i. o. w. that the assimilation predominates in the metabolism. 6. The differences in the amount of CO2 formed (or taken up) per unit of substrate consumed in cultures with different substrates are caused by the different oxidation values of the various substrates, the average oxidation value of the cell material of the bacteria being approximately the same with all substrates. 7. Since a consideration of assimilation in general leads to the insight that the greater majority of organic cell constituents is formed from the substrate via pyruvic acid, the ways in which this acid can be formed from the various substrates used in the experiments have been discussed. 8. The conversion of the substrate into pyruvic acid involves one or more dehydrogenations; a consideration of the hydrogen acceptors which may effect this dehydrogenation shows that CO2 must play a prominent part as an acceptor in this process. 9. In connection with point 2 this leads to the conclusion that photosynthetic processes are involved in the metabolism of the purple sulphur bacteria in organic media. 10. In the equation for photosynthesis in general: $${\text{CO}}_{\text{2}} {\text{ + }} {\text{2H}}_{\text{2}} {\text{A}} \to {\text{CH}}_{\text{2}} {\text{O}} {\text{ + }} {\text{2A}} {\text{ + }} {\text{H}}_{\text{2}} {\text{O}}$$ H2A may now be replaced by organic substances as well as by H2S or H2O.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00407535
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