The Dow Chemical Company

Robert A Houtchens

Roberta C Cheng

Norman G Moll

Karen M McCoy

Carol C Epstein

The subject invention concerns a process for stabilizing intact or ruptured microbial cells having glucose isomerase associated therewith. Specifically exemplified is a process for stabilizing glucose isomerase producing cells of a microorganism belonging to the genus Ampullariella. In the invention process the whole or ruptured microbial cells are contacted with a partially carboxyalkylated- or partially phosphonoalkylated-cationic polyelectrolyte, for example, a partially carboxymethylated polyethyleneimine to flocculate and stabilize the cells. The flocculated cells are further stabilized by encapsulation with a partially carboxyalkylated- or partially phosphonoalkylated-cationic polyelectrolyte. The encapsulation can be done prior to or after the flocculated cells are crosslinked. The net effect is manifested by a dramatic increase in the half-life of the glucose isomerase.

Stabilization of intracellular enzymes

Extracellular enzymes are stabilized with a carboxyalkylated or phosphonoalkylated polymer having a molecular weight of at least 500 Daltons. Exemplified is the stabilization of the enzyme glucose isomerase used in a process to convert D-glucose to D-fructose. In a preferred embodiment of the invention the feedstream containing the substrate is contacted initially with the stabilizer and then with the enzyme. In this system the stabilizer and enzyme are maintained in separate reactors. This separation, advantageously, results in a higher half-life for the enzyme.

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Midland, MI, United States of America

Robert A Houtchens