Pyruvates fermentation

Eschbach M, K Schreiber, K Trunk, J Buer, D Jahn, M Schobert (2004) Long-term anaerobic survival of the opportunistic pathogen Pseudomonas aeruginosa via pyruvate fermentation. J Bacteriol 186 4596-4604. 

Schreiber K, N Boes, M Eschbach, L Jaensch, J Wehland, T Bjarnsholt, M Givskov, M Hentzer, M Schobert (2006) Anaerobic survival of Pseudomonas aeruginosa by pyruvate fermentation requires an Usp-type stress protein. J Bacterial 188 659-668. 

Gram-positive sporeformer, DCB-2 Ortho and mete/pyruvate or H2 from pyruvate fermentation Madsen Licht (1992)... 

Wagner, N., Tran, Q. H., Richter, H., Selzer, P. M., and Unden, G. 2005. Pyruvate fermentation by Oenococcus oeni and Leuconostoc mesenteroid.es and role of pyruvate dehydrogenase in anaerobic fermentation. Appl. Environ. Microbiol., 71, 4966-4971. 

From the postulated fermentation pathway (Fig. 14) it is probable that glucose degradation to pyruvate is not coupled with net ATP synthesis. Thus, ADP-forming acetyl-CoA synthetase appears to be the only energy-conserving site during maltose (and pyruvate) fermentation, which is in accordance with the growth yield data [294,295]. The enzyme... 

Fig. 14. Proposed pathway of maltose and of pyruvate fermentation to acetate, H2 and CO2 in Pyrococcus furiosus. Fdox, oxidized ferredoxin Fdred, reduced ferredoxin CoA, coenzymeA. Numbers in circles refer to enzymes involved (1) Q-glucosidase [296] (2) glucoserferredoxin oxidoreductase (3) gluconate dehydratase (this enzyme has not been detected so far in Pyrococcus furiosus) (4) 2-keto-3-deoxygluconate aldolase (5) glyceraldehyde ferredoxin oxidoreductase (6) glycerate kinase (2-phosphoglycerate forming) (7) enolase (8) pyruvate kinase (9) pyruvateiferredoxin oxidoreductase (10) ADP-forming acetyl-CoA synthetase (11)...

For preparative purposes fermenting baker s yeast (Saccharomyces cerevisiae) is commonly used instead of a purified enzyme preparation. However, isolated pyruvate decarboxylates can also be used30. In this context, the most important substrate is benzaldehyde31 which is converted by n-glucosc fermenting yeast to (7 )-l-hydroxy-l-phenyl-2-propanone. This conversion has gained considerable industrial importance because ( )-l-hydroxy-1-phenyl-2-propanonc is an important precursor for the synthesis of (-)-cphedrin. 

The metabolic pathway for bacterial sugar fermentation proceeds through the Embden-Meyerhof-Paranas (EMP) pathway. The pathway involves many catalysed enzyme reactions which start with glucose, a six-carbon carbohydrate, and end with two moles of three carbon intermediates, pyruvate. The end pyruvate may go to lactate or be converted to acetyl CoA for the tricarboxylic acid (TCA) cycle. The fermentation pathways from pyruvate and the resulting end products are shown in Figures 9.7 and 9.8. 

Reactions involve several enzymes, which have to follow in sequence for lactic acid and alcohol fermentation. This is known as the glucose catabolism pathway, with emphasis on energetic and energy carrier molecules such as ATP, ADP, NAD+ and NADH. In this pathway the six-carbon substrate yields two three-carbon intermediates, each of which passes through a sequence of reactions to the stable end product of pyruvic acid. 

Pyruvic acid is an intermediate in the fermentation of grains. During fermentation the enzyme pyruvate carboxylase causes the pyruvate ion to release carbon dioxide. In one experiment a 200.-mL aqueous solution of the pyruvate in a sealed, rigid 500.-mL flask at 293 K had an initial concentration of 3.23 mmol-L -l. Because the concentration of the enzyme was kept constant, the reaction was pseudo-first order in pyruvate ion. The elimination of CU2 by the reaction was monitored by measuring the partial pressure of the C02 gas. The pressure of the gas was found to rise from zero to 100. Pa in 522 s. What is the rate constant of the pseudo-first order reaction ... 

Ephedrine and pseudoephediine are a vasodilator and decongestant respectively used widely in the treatment of asthma and the symptoms of colds and influenza. These pharmaceuticals were derived originally fi om the plant Ephedra sinica and used in traditional Chinese medicinal preparations. Although some are still produced fi om such sources, the major production is via a fermentation process followed by a chemical catalytic reaction. As shown in Figure 1, the intermediate / -phenylacetylcarbinol (PAC) is produced by decarboxylation of pyruvate followed by ligation to benzaldehyde. 

In current industrial practice, benzaldehyde is added to fermenting baker s yeast Saccharomyces cerevisiae) with resultant PAC production occurring from the yeast-derived pyruvate. Typically PAC concentrations of 12-15 g F are produced at yields of 65-70% theoretical in a 10-12 h biotransformation process. [2], Appreciable concentrations of benzyl alcohol are produced as by-product due to oxidoreductase activity in the fermentative yeast. 

The growth of Bacillus subtilis may take place under a variety of conditions (a) aerobic conditions, (b) using nitrate as electron acceptor, and (c) fermentative conditions with glucose provided pyruvate is available as an electron acceptor since the organism lacks pyruvate formate hydrogen lyase (Nakano and Zuber 1998). 

Xanthan (Figure 11) is a commercially important polysaccharide produced by the bacterium Xanthomonas campestris.187 188 The xanthan backbone consists of a P(l-4)-linked D-glucopyranose chain with a trisaccharide side chain attached at C3 to alternate glucose residues. These side chains consist of an acetylated mannose residue, a glucuronic acid residue, and a pyruvate ketal linked to a terminal mannose residue. The acetate and pyruvate content depend on the fermentation and isolation conditions used by the supplier. 

FIGURE 3.3. Illustration of some major pathways and end products of the bacterial fermentation of sugars from pyruvic acid (Stanier et al., 1986). 

The important part which acetaldehyde plays in alcoholic fermentation (C. Neuburg) is shown by the fact that it is formed by decarboxylation of the intermediate product, pyruvic acid ... 

Other microorganisms ferment sugars to succinic acid (HOOC-CH2-CH2-COOH), a promising intermediate for numerous chemicals [71]. Technical challenges include the toxicity of the succinate for the microorganisms, the need for expensive nutrients, the undesired co-production of acetic or pyruvic acid and the cost of acidifying the succinate to succinic acid. 

ATP-proton motive force interconversion Electron transport Entner-Doudoroff Fermentation Glycolysis/gluconeogenesis Pentose phosphate pathway Pyruvate dehydrogenase Sugars TCA cycle Methanogenesis Polysaccharides Other... 

Experiments with glyceraldehyde and dihydroxyacetone showed them to be fermentable, but results with methyl glyoxal were conflicting. With Lebedev juice no lactic acid was formed, but with top yeast Neuberg reported that lactic acid was detectable. In 1913 he and Kerb therefore proposed sugar was converted to methyl glyoxal from which pyruvic acid and ethanol were derived ... 

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