Glucose aerobic

Sodium fluoride (104) (1-10 mM) inhibits two enzymes of glycolysis the enolase (phosphopyruvate hydratase) and pyruvate kinase. Therefore, aerobic glucose utilization and lactate formation are blocked. 

After nitrogen enrichment, the exponential transitory phase of the power-time curve is clearly correlated with aerobic glucose metabolism, ATP pool level and oxygen tension (pC>2). The microevents noted on PTC during the exponential phase, are also observed on the oxygen-time curve (OTC) and a straight linear correlation is observed between the... 

Xanthan gum by aerobic glucose fermentation Xathomonas campestris... 

Figure 19. P-NMR spectra of aerobic glucose-grown Escherichia coli. The arrows indicate the frequencies of the low-power pulses used in B to saturate the nucleotide triphosphate (NTP) peak. The peaks labelled P-" and Pf correspond to intracellular and extracellular Pj, respectively. Peak NTP, consists of approximately 50% ATP and 50% nonadenine nucleotide triphosphates. The difference spectrum A — B) shows transfer of saturation from NTP, to P, (from [36]).

Figure 7 Evolution of the nitrogen ( ) and ash ( ) content of K. marxianus grown in aerobic glucose-limited continuous culture. (Redrawn from Reference [39] with permission of the author and publisher).

As noted above, all vitamin is produced by microbial fermentation. A partial Hst of microorganisms that synthesize vitamin B 2 under appropriate conditions follows. Most strains, in their wild state, produce less than 10 mg/L vitamin although a few approach 40 mg/L. The organisms are both aerobes and anaerobes. The carbon requirements in the fermentations are satisfied from sources as wide ranging as hydrocarbons, methanol, and glucose. 

A commercial bacterial cellulose product (CeUulon) was recently introduced by Weyerhaeuser (12). The fiber is produced by an aerobic fermentation of glucose from com symp in an agitated fermentor (13,14). Because of a small particle diameter (10 P-m), it has a surface area 300 times greater than normal wood cellulose, and gives a smooth mouthfeel to formulations in which it is included. CeUulon has an unusual level of water binding and works with other viscosity builders to improve their effectiveness. It is anticipated that it wiU achieve GRAS status, and is neutral in sensory quaUty microcrystaUine ceUulose has similar attributes. 

Aerobic Fermentation The classic example of large-scale aerobic fermentation is the production of penicillin by the growth of a specific mold. Commercial vessel sizes are 40,000 to 200,000 L (1,400 to 7,000 ft ). The operation is semibatch in that the lactose or glucose nutrient and air are charged at controlled rates to a precharged batch of liquid nutrients and cell mass. Reaction time is 5 to 6 days. 

Glycolysis and the citric acid cycle (to be discussed in Chapter 20) are coupled via phosphofructokinase, because citrate, an intermediate in the citric acid cycle, is an allosteric inhibitor of phosphofructokinase. When the citric acid cycle reaches saturation, glycolysis (which feeds the citric acid cycle under aerobic conditions) slows down. The citric acid cycle directs electrons into the electron transport chain (for the purpose of ATP synthesis in oxidative phosphorylation) and also provides precursor molecules for biosynthetic pathways. Inhibition of glycolysis by citrate ensures that glucose will not be committed to these activities if the citric acid cycle is already saturated. 

A bacterium is grown aerobically with glucose as sole source of carbon and ammonium ions as nitrogen source. Experimental analysis shows that six moles of glucose are utilised for each mole of biomass produced. Write the reaction equation for growth if the elemental composition of the cells is CHi,666 CW Nojd. 

The empirical formula for glucose is C6H12O6 and for itaconic add it is C5H6O4, so itaconic add production is another aerobic fermentation and requires aeration. 

From the literature the following stoichiometric equation for E. coli growing aerobic on glucose is well known. 

One of the commercial methods for production of lysine consists of a two-stage process using two species of bacteria. The carbon sources for production of amino acids are corn, potato starch, molasses, and whey. If starch is used, it must be hydrolysed to glucose to achieve higher yield. Escherichia coli is grown in a medium consisting of glycerol, corn-steep liquor and di-ammonium phosphate under aerobic conditions, with temperature and pH controlled. 

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