Date of Award

1992

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

School of Nutrition and Food Sciences

First Advisor

Donal F. Day

Abstract

A new process for the production of clinical (or controlled size) dextran was developed. This process is simpler, cheaper and more economical than traditional methods. It involves the use of a mixed culture fermentation with a dextranase producing strain (Lipomyces starkeyi ATCC 74054) and a dextransucrase producing strain (Leuconostoc mesenteroides ATCC 10830). The new process produced 84% (w/w) of theoretical yield clinical dextran with an average polydispersity between 1.2 and 1.5. The mechanism of clinical dextran formation is the competitive production of acceptors from newly formed dextran molecules by dextranase. The acceptors compete for the existing glucosyl portion of sucrose, resulting in higher levels of smaller size dextran molecules. The maintenance of a proper balance of dextransucrase to dextranase is essential for the functioning of this process.

Pages

179

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