Heterotrophic Carbon Dioxide Fixation

The utilization of atmospheric carbon dioxide for the synthesis of the constituents of living matter had, until then, been thought to be the prerogative of photosynthetic and chemosynthetic organisms. The occurrence of carbon dioxide fixation in heterotrophic cells, anticipated by Lebedev over thirty years ago (220), was generally recognized only when isotopes of carbon became available. 

Carbon Dioxide, Fixation by Heterotrophs and Autotrophs (Utter... 

Gantt E., Lipschultz C.A. Zilinskas B.A. (1977) Phycobilisomes in relation to the thylakoid membranes, Brookhaven Symp. Biol. 28, 357-357. Joset-Espardellier-F., Astier C., Evans E.H. and Carr, N.G. (1978) Cyanobacteria grown under Photoautotrophic, Photoheterotrophic and Heterotrophic regimes sugar metabolism and carbon dioxide fixation,... 

Common heterotrophs depend on preformed organic compounds for all three primary needs. Although some carbon dioxide is fixed in heterotrophic metabolism, the het-erotrophic cell thrives at the expense of compounds formed by other cells, and is not capable of the net conversion (fixation) of carbon dioxide into organic compounds. Some bacteria referred to as photoheterotrophs are able to regenerate ATP photochemically but cannot use photochemical reactions to supply electrons to NADP+. Such organisms are like other heterotrophs in their dependence on preformed organic compounds. But because of their photochemical... 

Carbon dioxide is also fixed in the dark by photosynthetic organisms by the so-called Wood-Werkman reaction (Wood and Stjemholm, 1962). The CO2 assimilated, however, rarely exceeds that formed by dark respiration i.e. there is no net CO2 uptake. On the other hand, the amount of organic carbon derived from CO2 may be as high as 30% in heterotrophic bacteria and 90% in mixotrophic organisms. In the natural environment, non-photo-synthetic CO2 fixation by these organisms, together with the above-mentioned dark fixation by photosynthetic organisms, may under some condi-... 

One of these is by heterotrophic CO2 fixation, first discovered in propionic acid bacteria by Wood and Workman (1936, 1938). The CO2 fixation is especially high when the bacteria are grown on glycerol. Both the fixation of carbon dioxide and formation of succinate by propionibacteria are inhibited by NaF (Wood and Workman, 1940). Another pathway of the condensation of C3- and Ci-compounds was discovered by Swick and Wood (1960), who showed that lliese bacteria contain a transcarboxylase that has a role in producing propionate firom methylmalonyl-CoA. This was preceded by an observation (Wood and Leaver, 1953) fiiat propionic acid bacteria have two mechanisms for CO2 fixation and only one of these is inhibited by NaF. The enzyme, discovered by Swick and Wood, catalyzed a new type of biochemical reactions— transcarboxylation between a carboxyl donor and an acceptor ... 

Heterotrophs, Fixation of Carbon Dioxide by (Utter and Wood)... XII 41... 

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