The Pasteur effect

In propionic acid bacteria the Pasteur effect, although less prominent than in the yeast, was found for the first time in P. pentosaceum in 1939 (Chaix and Fromageot). It is known that in yeasts growing under anaerobic conditions the effect is manifested by consuming more substrate to synthesize a unit of biomass than under aerobic conditions. In yeasts, the mechanism of the Pasteur effect may be connected with changes in the enzyme activities of the 

Following an abrupt transition of P. pentosaceum from anaerobic to aerobic metabolism (10 pM O2), the growth rate increases at first, but the formation of acetate from lactate and glucose is slowed down, propionate formation is completely repressed and pyruvate is accumulated in the medium (van Gent-Ruijters et al, 1976 Schwartz et al, 1976). A decrease in the activities of the citric acid cycle enzymes malate dehydrogenase, fumarase and NADH oxidase, lactate oxidase, NADH-dependent fiimarate reductase, lactate-dependent nitrate reductase is observed upon the transition from anaerobic to aerobic (10 pM O2) metabolism (van Gent-Ruijters, 1975). 

Placed under strictly aerobic conditions (on the surface of a plate), P. shermanii does not grow at all It was found that the lack of growth is explained by the repression of cytochromes b, d and a, which is due to the repression by oxygen of the synthesis of ALA synthetase and ALA dehydratase (Menon, Shemin, 1967). 

In liquid medium, P. shermanii and P. freudenreichii grew more slowly under aeration than P. pentosaceum or P. rubrum (de Vries et al., 1972), and the extent of inhibition of the cytochrome synthesis was higher in strains 

When the O2 concentration exceeded the utilization capacity of the culture so that free oxygen accumulated in the medium (when the p02 was 520 mm Hg), the growth was suppressed, NADH oxidase and L-lactate dehydrogenase were inactivated, SOD activity was reduced, but D-lactate dehydrogenase and succinate dehydrogenase activities remained unchanged. 

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Pasteur effect Yeast and other cells can break down sugar in the presence of oxygen (eventually to CO2 and H2O) or in its absence (to CO2 and ethanol). The decomposition of sugar is often greater in the absence of oxygen than in its presence, i.e. the Pasteur effect. With oxygen, less toxic products (alcohol) are produced and the breakdown is more efficient in terms of energy production. 

Since more ATP is produced by respiration of glucose than by fermentation, and since the ATP requirement for biosynthesis of cell mass is the same, it follows that to obtain the same cell yield from glucose, the yeast should consume less sugar under aerobic conditions than under anaerobic conditions, with a resultant decrease in glycolytic flux (Berry, 1982). These phenomena are referred to as the Pasteur effect. Although this effect is observed in some yeasts, in S. cerevisiae it is either absent (Gancedo and Serrano, 1989) or observed only under certain nutrient-limited conditions. The main reason for the absence of the Pasteur effect is that even under aerobic conditions, fermentation is still the main catabolic route for the utilisation of glucose because of the Crabtree effect (Walker, 1994). The Crabtree effect is the repression... 

Glucose and its Role in the Pasteur Effect, Biochim. Biophys. Acta (1967) 135,166. 

Traditionally, biologists views of cell-level responses to 02 limitation are formalized in the concept of the Pasteur effect as ATP generation by oxidative phosphorylation begins to fall off due to oxygen lack, the energetic deficit... 

Schmidt H., and G. Kamp (1996). The Pasteur effect in facultative anaerobic metazoa. Experientia 52 440-448. 

Answer The addition of oxygen to an anaerobic suspension allows cells to convert from fermentation to oxidative phosphorylation as a mechanism for reoxidizing NADH and making ATP. Because ATP synthesis is much more efficient under aerobic conditions, the amount of glucose needed will decrease (the Pasteur effect). This decreased utilization of glucose in the presence of oxygen can be demonstrated in any tissue that is capable of aerobic and anaerobic glycolysis. 

A good illustration of how glycolytic flux can rapidly change is seen when yeast are grown under aerobic and anaerobic conditions with glucose as the carbon source. This effect, first observed by Louis Pasteur, is called the Pasteur effect and is depicted in Fig. 11-21. 

Fig. 11-21 The Pasteur effect metabolic activity of yeast grown under aerobic and anaerobic conditions.

Addition of oxygen to cells metabolizing glucose under anaerobic conditions leads to (a) a decrease in the rate of glucose consumption and (b) cessation of lactate accumulation. The latter phenomenon is known as the Pasteur effect. Explain why these changes occur in glucose and lactate metabolism. 

This phenomenon, which is known as the Pasteur effect, has been attributed to several mechanisms (Barnett and Entian 2005). Respiration needs very high amounts of ADP inside the mitochondria as a subtract for oxidative phosphorylation. Therefore, when respiration takes place, the cytoplasm lacks ADP and inorganic phosphate (Lagunas and Gancedo 1983), which in turn decreases the sugar transport inside the cell (Lagunas et al. 1982). These mechanisms explain how aeration inhibits the alcoholic fermentation. 

Lagunas, R., Dominguez, C., Busturia, A., Saez, M.J. (1982) Mechanisms of appearance of the Pasteur effect in Saccharomyces cerevisiae inactivation of sugar transport systems. J. Bacte-riol, 152, 19-25... 

Racket, E. (1974) History of the Pasteur effect and its pathobiology. Mol. Cell. Biochem., 5,17-23. 

The inhibition of glycolysis by respiration, discovered by Louis Pasteur in studying fermentation by yeast. The consumption of carbohydrate is about sevenfold lower under aerobic conditions than under anaerobic ones. The inhibition of phosphoifuctokinase by citrate and ATP accounts for much of the Pasteur effect. 

So, when there is a change from anaerobic to aerobic conditions, there is a diminution in the consumption of D-glucose. This is termed the Pasteur effect. The action of oxygen in diminishing carbohydrate breakdown, and in decreasing the accumulation of the products of anaerobic metabolism, was first described by Pasteur,270 who found271 that, in the presence of air, the ratio of weight of yeast... 

Much has been published on the controversial subject of the control of glycolysis. The following brief summary of some of the controls responsible for the Pasteur effect in yeasts is based mainly on a review by Sols and coworkers144 (see also, Fig. 7). (i) Isocitrate dehydrogenase (NAD ) (EC 1.1.1.41), one of the controlling enzymes of the tricarboxylic acid cycle (see Fig. 5), catalyzes the reaction... 

Hypoxia-Inducible Factor-lcz is a Necessary Mediator of the Pasteur Effect. 238... 

In terms of mechanisms, the Pasteur effect came into play when the decreased oxidative phosphoynglasin in hypoxic response is abolished that is, when the aerobic metabolism is abolished, the anaerobic metabohsm takes over. Perhaps, the same phenomenon is working here, at least in part. 

The Pasteur effect includes decreased oxidative phosphorylation and an increase in anaerobic fermentation. Because fermentation produces far less ATP than oxidative phosphorylation per molecule of glucose, increased activity of the glycolytic pathway is necessary to maintain the ATP levels in the hypoxic ceUs. 

Seagraves TN, Ryna HE, Lu H, Wouters BG, Knapp M, et al. 2001. Transcription factor HIF-1 is a necessary mediator of the Pasteur effect in mammalian cells. Mol CeU Biol 21 3436-3444. 

Storey, K. B. (1985a). A re-evaluation of the Pasteur effect new mechanisms in anaerobic metabolism. Mol. Physiol. 8, 439-461. 

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