130 Fermentation and Biochemical engineering Handbook The Embden-Meyerhof pathway(EMP) he Krebs or tricarboxylic acid cycle(tCa) hosphate pathway(Ppp) In the EMP, glucose is anaerobically converted to pyruvic acid and or to either ethanol or lactic acid From pyruvic acid it may also enter the oxidative TCa pathway. Per mole of glucose broken down, a net gain of 2 moles of ATP is being obtained in the EMP. The EMP is also the entrance for glucose fructose and galactose into the aerobic metabolic pathways such as the TCA-cycle. In cells containing the additional aerobic pathways the NADH, that forms in the EMP where glyceraldehyde-3-phosphate is converted into 3-phosphoglyceric acid, enters the oxidative phosphorylation scheme and results in ATP generation. 31 In fermentative organisms the pyruvic acid formed in the eMp pathway may be the precursor to many products, such as ethanol, lactic acid, butyric acid(butanol), acetone and isopropanol. II The TCA-cycle functions to convert pyruvic and lactic acids, the end products of anaerobic glycolysis(EMP), to CO2 and H2O. It also is a common channel for the ultimate oxidation of fatty acids and the carbon skeletons of many amino acids. The overall reaction is 2C3H4O3+502+30ADP+30P1→6C02+4H2O+30ATP for pyruvic acid as the starting material. 31 Obviously, the EMP-pathway and TCA-cycle are the major sources of ATP energy, while they also provide intermediates for lipid and amino acid synthesis The PPP handles pentoses and is important for nucleotide(nibose-5 phosphate)and fatty acid biosynthesis(NADPH2 ). The Entner-Doudoroff hway catabolizes glucose into pyruvate and glyceraldehyde- 3-phosphate It is important primarily in Gram negative prokaryotes. 161 The yeast Saccharomyces cerevisiae will ferment glucose, fructose and sucrose without any difficulties, as long as the minimal nutritional requirements of niacin(for NAD), inorganic phosphorus( for phosphate groups in 1, 3-diphosphoglyceric acid and ATP)and magnesium(catalyzes with hexokinase and phosphofructokinase, the conversion of glucose to lucose-6-phosphate and fructose-6-phosphate to fructose-1, 6-diphosphate) are met. Table 2 lists some of the important biological molecules involved in catabolism and anabolism. 3IS cerevisiae ferments galactose and maltose occasionally, but slowly; inulin very poorly; raffinose only to theextent of oneI30 Fermentation and Biochemical Engineering Handbook - The Embden-Meyerhof pathway (EMP) - - The pentose-phosphate pathway (PPP) The Krebs or tricarboxylic acid cycle (TCA) In the EMP, glucose is anaerobically converted to pyruvic acid and on to either ethanol or lactic acid. From pyruvic acid it may also enter the oxidative TCA pathway. Per mole of glucose broken down, a net gain of 2 moles of ATP is being obtained in the EMP. The EMP is also the entrance for glucose, fructose, and galactose into the aerobic metabolic pathways, such as the TCA-cycle, In cells containing the additional aerobic pathways, the NADH, that forms in the EMP where glyceraldehyde-3-phosphate is converted into 3 -phosphoglyceric acid, enters the oxidative phosphorylation scheme and results in ATP generation.L3I In fermentative organisms the pyruvic acid formed in the EMP pathway may be the precursor to many products, such as ethanol, lactic acid, butyric acid (butanol), acetone and isopropanol.['] The TCA-cycle functions to convert pyruvic and lactic acids, the end products of anaerobic glycolysis (EMP), to CO, and H,O. It also is a common channel for the ultimate oxidation of fatty acids and the carbon skeletons of many amino acids. The overall reaction is: 2C3H403 + 502 + 30 ADP + 30 P; + 6C0, + 4H2O + 30 ATP for pyruvic acid as the starting material.L3I Obviously, the EMP-pathway and TCA-cycle are the major sources of ATP energy, while they also provide intermediates for lipid and amino acid synthesis. The PPP handles pentoses and is important for nucleotide (ribose-5- phosphate) and fatty acid biosynthesis (NADPH,). The Entner-Doudoroff pathway catabolizes glucose into pyruvate and glyceraldehyde-3 -phosphate. It is important primarily in Gram negative The yeast Saccharomyces cerevisiae will ferment glucose, fructose and sucrose without any difficulties, as long as the minimal nutritional requirements of niacin (for NAD), inorganic phosphorus (for phosphate groups in 1 , 3-diphosphoglyceric acid and ATP) and magnesium (catalyzes, with hexokinase and phosphofructokinase, the conversion of glucose to glucose-6-phosphate and fructose-6-phosphate to fructose- 1,6-diphosphate) are met. Table 2 lists some of the important biological molecules involved in catabolism and S. cerevisiae ferments galactose and maltose occasionally, but slowly; inulin very poorly; raffinose only to the extent of one