MOLECULAR WEIGHT DISTRIBUTION AND BRANCHING FREQUENCY OF DEXTRAN PRODUCED BY FREE AND IN CALCIUM ALGINATE IMMOBILIZED LEUCONOSTOC MESENTEROIDES

Document Type : Original Article

Authors

1 Department of Microbiology, Faculty of Pharmacy, Zagazig University, Egypt

2 SymBiotech, Inc. and Department of Chemical Engineering, University of Connecticut, Storrs, CT, USA

Abstract

Dextran was produced using in 3% calcium alginate immobilized and free cells of L. mesenteroides ATCC 10830 (NRRL B-512 F). Information about the molecular structure of the produced polymers using size exclusion chromatography and on-line low angle laser light scattering (SEC/LALLS) detection was obtained. Dextran formed outside the beads by immobilized cells possesses an average molecular weight of about 1.84 x 107 daltons. Average molecular weight of dextran formed by free cells, however, was 1.32 times (2.43 x107 daltons for free cells) that formed by immobilized cells. Determination of the qualitative branching parameters (G-1 v and GM) of dextran formed by both cultures shows that branching of dextran produced by free cells was also higher than that produced by immobilized cells in calcium alginate.