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Published on: October 24, 2016
Simultaneous enzymatic synthesis of gluconic acid and sorbitol. Continuous process development using glucose-fructose
M Silva-Martinez1, D Haltrich, S Novalic
1Division of Biochemical Engineering, Institute of Food Technology, Universität für Bodenkultur Wien (BOKU), Muthgasse 18, A-1190 Vienna, Austria.
Abstract:
The production of sorbitol and gluconic acid by isolated glucose-fructose oxidoreductase (GFOR) from Zymomonas mobilis has been studied in a convective, 100-mL loop reactor with tangential ultrafiltration. Using a dilution rate of 0.04/h and 5 kU/L GFOR, substrate conversion (3 M sugar) in a single stage was >85%, and productivities of 126 g sorbitol/(L x d) were obtained. At a constant recycle rate (3/min) and a membrane area of 50 cm2, the dilution rates (and thus productivities) were however limited by a more than 30-fold reduction of the permeate flow in the presence of high sugar and protein concentrations (5 g/L). Protein was added, together with 10 mM dithiothreitol, to improve the stability of GFOR during substrate turnover and crossflow filtration, thus leading to a stable operation of the enzyme reactor for at least 5 d.
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Cells make energy by breaking down macromolecules. Cellular respiration is the biochemical process that converts "food energy" (from the chemical bonds of macromolecules) into chemical energy in the form of adenosine triphosphate (ATP). The first step of this tightly regulated and intricate process is glycolysis. The word glycolysis originates from the Latin glyco (sugar) and lysis (breakdown). Glycolysis serves two main intracellular functions: generating ATP and generating...

