Glucose, oxygen demand

The carbon source affects oxygen demand. In penicillin production, oxygen demand for glucose is 4.9 mol 1 1 h-1. The lactose concentration is 6.7 mol 1 1 h 1, sucrose is 13.4 mol l-1 h. The yield of oxygen per mole of carbon source for CH4 is YQjC = 1.34, T0j/C for Paraffins = 1, and Y(> /c for hydrocarbon (CH20)n = 0.4. The mass transfer coefficient k,a is for gas-liquid reactions, and the film thickness where the mass transfer takes place is 8... 

Lactose, the milk sugar, is a reducing disaccharide consisting of glucose and galactose moieties. The estimated annual worldwide availability of lactose as a byproduct from cheese manufacture is several million tons [1,2], but only about 400 000 t/a lactose is processed further from cheese whey [3], Non-processed whey is an environmental problem due to its high biochemical and chemical oxygen demand [2], The use of lactose as such is limited by two main factors relatively low solubility of lactose in most solvents and lactose intolerance in human body [1]. 

Wastewater treatment is relatively simple in that the sole purpose is the degradation of all the organic species present in the liquid to remove both biological oxygen demand (BOD) and chemical oxygen demand (COD). Three-phase fluidization is also of interest for bioremediation of contaminated soils. Production of alcohols by fermentation (e.g., ethanol from glucose) has been practiced commercially. Other fermentation processes have been examined for production of enzymes, acetic acid, stem cells, monoclonal antibodies, antibiotics, and other pharmaceutical products. 

Mullen et al. (1985) circumvented the problem of oxygen demand by using quinoprotein glucose dehydrogenase from Pseudomonas or Acme-... 

Kessler et al. (1984) developed a glucose sensor with an extremely low oxygen demand and a stability of 3 months, which appears to be suitable for implantation. Another sensor that might be implantable is based on the use of ferrocene as an electron acceptor for GOD (Cass et al., 1984 David et al., 1985), which eliminates the need for oxygen. The sensor exhibits an advantageous linear range of 1-30 mmol/l. However, experiments with the sensor implanted subcutaneously in animals revealed a rapid sensitivity decrease (Pickup, 1987). 

In fed-batch culture, a fresh medium which contains a substrate but no cells is fed to the fermentor, without product removal. This type of operation is practiced in order to avoid excessive cell growth rates with too-high oxygen demands and catabolite repression with high glucose concentration, or for other reasons. Fed-batch operations are widely adopted in the culture of baker s yeast, for example. 

Response curves of Bacillus subtilis- and THchosporon cutaneum-based sensors to glucose-glutamic acid standard solution containing 22 mg/L biochemical oxygen demand (BOD). Reproduced from (420] with permission from Springer-Verlag. 

The same approach can be utilized in the construction of sensors cathodicaly monitoring the oxygen demand. Beside elimination of interfering effects, a signal is then produced which is directly glucose-concentration-dependent and, in a certain range, independent of oxygen concentratin in the electrolyte (a buffer solution with the compounds needed to obtain the optimal rate of enzymatic reaction). 

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