Crabtree effect

This is the reverse Pasteur or Crabtree effect and is also known as glucose inhibition or cataboHte repression. In the presence of higher sugar concentrations, synthesis of respiratory enzymes such as cytochromes is inhibited. 

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... 

Marroquin, L.D. et al. (2007) Circumventing the Crabtree effect replacing media glucose with galactose increases susceptibility of HepG2 cells to mitochondrial toxicants. Toxicological Sciences, 97 (2), 539-547. 

However, if an anaerobic metabolism such as ethanol fermentation occurs in a fermentor in the presence of high concentration of glucose, the RQ value becomes larger than 1.0, known as the Crabtree effect. This is because CO2 evolves without O2 consumption as follows. 

Regulation Between Respiration and Fermentation Pasteur and Crabtree Effects. 9... 

The Crabtree effect does not operate in all species of the genus Saccharo-myces and is absent in Hansenula sp. and Candida sp. (Table 17.5). The effect is expressed in the presence of fructose as well as glucose but is less marked when maltose, mannose or galactose is the fermentable carbohydrate (Table 17.6). 

Presence of the Crabtree effect in various yeast strains [51] ... 

Crabtree effect a decrease in respiration rate after addition of glucose, when studied in isolated systems such as asdtes tumor cells. This is probably due to a more effective competition by glycolysis for inorganic phosphate and NADH, leading to a deficiency of these materials for oxidative phosphorylation. 

Although it seems logical to conclude a discussion on glycolysis by considering the Pasteur and Crabtree effects, it is more appropriate to review these phenomena in the chapter devoted to cancer metabolism. 

Doelle HW (1981) New developments in the elucidation of the mechanisms of the Pasteur and Crabtree effects in bacteria. Adv Biotechnol Proc 6th Int Ferment Symp, London (Canada), July 20-24,1980, vol 1, pp 249-254... 

Siso, M. I. G., Ramil, E., Cerdan, M. E., and Freire Picos, M. A. (1996). Respirofermentative metabolism in Khtyveromyces lactis Ethanol production and the Crabtree effect. Enzyme Microbiol Technol 18, 585-591. 

Wu, R. and Racker, E. (1959) Regulatory mechanisms in carbohydrate metabolism. IV. Pasteur effect and crabtree effect in ascites tumor cells. J. Biol. Chem. 234,1036. 

Fermentation and Respiration Pasteur Effect and Crabtree Effect... 

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