Glucose microbial

Another microbial polysaccharide-based emulsifier is Hposan, produced by the yeast Candida lipolytica when grown on hydrocarbons (223). Liposan is apparentiy induced by certain water-immiscible hydrocarbons. It is composed of approximately 83% polysaccharide and 17% protein (224). The polysaccharide portion consists of D-glucose, D-galactose, 2-amino-2-deoxy-D-galactose, and D-galacturonic acid. The presence of fatty acyl groups has not been demonstrated the protein portion may confer some hydrophobic properties on the complex. 

After recovery of L-lysine, the residual dl-(49) is epimerized to a mixture of the DL and meso isomers, and the latter is subjected to the same decarboxylation step. This reaction is a part of a microbial process in which glucose is fermented by a lysine auxotroph of E. coli to meso- which accumulates in the medium. Meso-(49) is quantitatively decarboxylated to L-lysine by cell suspensions oi erobacteraerogenes (93). However, L-lysine and some... 

Polarimetric determination of the sucrose concentration of a solution is vaUd when sucrose is the only optically active constituent of the sample. In practice, sugar solutions are almost never pure, but contain other optically active substances, most notably the products of sucrose inversion, fmctose and glucose, and sometimes also the microbial polysaccharide dextran, which is dextrorotatory. Corrections can be made for the presence of impurities, such as invert, moisture, and ash. The advantage of polarization is that it is rapid, easy, and very reproducible, having a precision of 0.001°. 

I onsucrose Components from Storage or Damag e of Beets. Some nonsucrose components are associated with the conditions under which the beets have been stored prior to processing, as respiration products or products of microbial attack In either case they direcdy and indirectly reduce sucrose yield and may cause other processing problems. Glucose and fmctose have already been discussed and can derive from either source. 

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. 

Increasingly, biochemical transformations are used to modify renewable resources into useful materials (see Microbial transformations). Fermentation (qv) to ethanol is the oldest of such conversions. Another example is the ceU-free enzyme catalyzed isomerization of glucose to fmctose for use as sweeteners (qv). The enzymatic hydrolysis of cellulose is a biochemical competitor for the acid catalyzed reaction. 

E-number and generic name, eg, lysozyme or glucose oxidase. AMEEP has defined Good Manufacturing Practice (GMP) for microbial food enzymes. 

In most animal, plant, and microbial cells, the enzyme that phosphorylates glucose is hexokinase. Magnesium ion (Mg ) is required for this reaction, as for the other kinase enzymes in the glycolytic pathway. The true substrate for the hexokinase reaction is MgATP. The apparent K , for glucose of the animal... 

Examples of rare sugars which have been found in some microbial polysaccharides are L-glucose ... 

Figure 7.5 Production of xanthan gum in batch culture using X. campestris. Bacterial dry weight ( ) xanthan gum ( ) residual glucose ( ) residual glutamate (A). Adapted from Microbial exopolysaccharide, Yenton etai pp 217-261. In biomaterials Novel Materials from Biological Sources, D Byrom (Ed), MacMillan Academic Professional Ltd, 1991.

Microbial over-growth was controlled with carbon dioxide passed through the bed. There was a maximum 30% increase in the beads diameter at the lower part of column, where the glucose concentration was maximum. The void volume was measured by passing sterilised water. In addition to the carbon source, the feeding media consisted of 1 g l 1 yeast extract pumped from the bottom of the reactor, while the flow rate was constant for a minimum duration of 24 hours. 

Acarbose and Miglitol These agents are specific inhibitors of intestinal glucosidases and reduce the conversion of sucrose and starch to glucose. Their main effect is a delay, not a complete inhibition, of the absorption of carbohydrates. Postprandial blood sugar excursions are effectively reduced. Because a small portion of the carbohydrates enters the colon, their microbial degradation frequently causes flatulence or... 

TABLE 3.3 Potential Routes to Commodity Chemicals by Microbial Fermentation of Glucose... 

Bacteria in thawed ice samples from Ellesmere Island (79°38 N, 74°23 W) produced CO2 and CH4 during extended incubation at 4°C in a diluted complex medium (yeast extract, casamino acids, starch, and glucose) (Skidmore et al. 2000). It was suggested that the results demonstrated that the subglacial environment beneath a polythermal glacier provided an acceptable habitat for microbial life. 

In some cases it is more attractive to use whole microbial cells, rather than isolated enzymes, as biocatalysts. This is the case in many oxidative biotransformations where cofactor regeneration is required and/or the enzyme has low stability outside the cell. By performing the reaction as a fermentation, i.e. with growing microbial cells, the cofactor is continuously regenerated from the energy source, e.g. glucose. 

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