An energetic model for oxygen‐limited metabolism

Abstract

Microbial production of 2,3-butanediol by Klebsiella oxytoca occurs under conditions of an oxygen limitation. The extent to which substrate is oxidized to 2,3-butanediol and its coproducts, (acetic acid, acetoin, and ethanol) and the relative flow rates of substrate to energetic and biosynthetic pathways are controlled by the degree of oxygen limitation. Two energetic relationships which describe the response to an oxygen limitation have been derived. The first relationship describes the coupling between growth and energy production observed under oxygen-limited conditions. This allows calculation of energetic parameters and modeling of the cell mass and substrate profiles in terms of the degree of oxygen limitation only. The second relationship describes the average degree of oxidation and the rate of the end-product flow. The model has been tested with both batch and continuous culture. During these kinetic studies, two phases of growth have been observed: energy-coupled growth, which was described above; and, energy-uncoupled growth, which arises when the degree of oxygen limitation reaches a critical value. Optimal culture performance with respect to 2,3-butanediol productivity occurs during energy-coupled growth.

Automatic Control for the Production of Alginate by Azotobacter Vinelandii

“…It also can synthesize at least two molecules of biotechnological interest: alginate and poly (3-hydroxybutyrate) (PHB). An aspect of great importance in the production of microbial polysaccharides is the ability to influence their composition and properties, by controlling the conditions in the culture medium, in addition to the possibility of obtaining alginate of uniform composition [1], [20]. Figure 1 shows the four stages of production of alginate from A. vinelandii, relating the growth of the bacteria with the consumption of the substrate (sucrose) and the production of alginate.…”

Activated sludge and other aerobic suspended culture processes

“…Microbial activity under oxygen-limited conditions was modeled using two energetic relationships (Beronio and Tsao, 1993). Experimental studies conducted for model verification using batch and continuous flow systems indicated that suboptimal microbial activity occurred with oxygen limitations above a theoretical critical level.…”