Propionic acid bacteria fixation

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 ... 

Reaction 3.1, the key reaction of propionic acid fermentation, is catalyzed by pyruvate carboxytransphosphorylase, a unique biotin-dependent transcarboxylase (see below). There are other reactions of carboxyl group transfer catalyzed by phosphoenolpyruvate (PEP) carboxytransphosphorylase and phosphoenolpyruvate carboxykinase, but these (i) do not require biotin and (ii) use CO2 as the source of carboxyl groups. The actual species involved may be HCO3" (or H2CO3) rather than free CO2 (Cooper et al., 1968), since free CO2 is not evolved in the PEP carboxytransphosphorylase reaction (Swick and Wood, 1960). Propionic acid bacteria are able to decarboxylate succinate, producing CO2 in a biotin-dependent reaction (Delwiche,1948 Lichstein, 1958). If succinate is accumulated as the end product, then the cycle (see Fig. 3.1) is broken, and oxaloacetic acid is not supplied by reaction 3.1, but is formed primarily by CO2 fixation onto PEP catalyzed by PEP carboxytransphosphorylase (PEP-CTP). 

Biosynthetic capabilities of propionibacteria are well developed, although they vary in different strains. The finding of nitrogen fixation, of the ability to utilize paraffins (alkanes), of independent syntheses of many vitamins have widened our ideas of the life boundaries of propionic acid bacteria. 

Kraeva NI and Vorobjeva LI (1981b) Superoxide dismutase, catalase, and peroxidase of propionic acid bacteria. Mikrobiologiya 50 813-817 Krebs flA and Eggleston LV (1941) Biological synthesis of oxaloacetic acid from pyruvic acid and carbon dioxide. II. The mechanism of carbon dioxide fixation in propionic acid bacteria. Biochem J 35 676-687... 

Silverman M and Werkman CH (1939) Adaptation of the propionic acid bacteria to vitamin Bi synthesis including method of assay. J Bacteriol 38 25-32 Siu PML and Wood HG (1962) Phosphoenolpyruvic carboxytransphosphorylase, a CO2 fixation enzyme from propionic acid bacteria. J Biol Chem 237 3044-3051 Sizova AV and Arkadjeva ZA (1968) Propionic acid bacteria of rumen and their capacity for vitamin B12 biosynthesis. Mikrobiol Sintez 10 8-13... 

Strangely, we had never turned our attention to determining how CO2 is fixed by the propionic acid bacteria and in 1961 when we did get to this problem we discovered, to our surprise, a new enzyme for fixation of CO2. There were three enzymes which were known to fix CO2 into oxalacetate at that time, P-enolpyruvate carboxylase discovered by R. S. Bandurski and G. M. Griener in 1953,... 

So we had these latter enzymes under consideration as well. Rune Stjernholm and I made crude extracts of the propionic acid bacteria and using the proper substrates we looked for C02 conversion to the expected compounds. As a test of COa fixation we simply bubbled C02 through the incubation mixture after making it acid and then determined if there was radioactivity remaining in the mixture. We soon found with P-enolpyruvate... 

It was not before 1949 that Thomas (1949), and Wolf (1949), stimulated by the discovery of nonphotosynthetic CO2 fixation in propionic bacteria by Wood and Werkmann (1938), recognized dark CO2 fixation as a missing link in the causal chain leading to dark malic acid accumulation during CAM. 

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