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Dextran is a generic term for a bacterial exopolysaccharide synthesized from sucrose and composed of chains of D- glucose units connected by α -1,6-linkages by using dextransucrases. Dextran can be branched out by α -1,2, α -1,3, or α -1,4-linkages, to varying degrees, depending on the strain of Leuconostoc sp. Recently, dextrans have been investigated for delivery of drugs, proteins/enzymes, and imaging agents. L. mesenteroides ATCC 13146 produces two dextransucrases which synthesize two branched dextrans: soluble (S) type and less soluble (L) type. Soluble dextran (precipitated by 45% ethanol) contains 50% of α -D-(1-6) glucose linkages and 50% of α -(1-3) branch linkages. Less soluble dextran (precipitated by 39% alcohol) is made up of 87% of α -D-(1-6) glucose linkages and 13% of α -D-(1-4) branch linkages. In this study dextrans of L. mesenteroides ATCC 13146 was produced by batch fermentation and separated into two different kinds. The less soluble dextrans were precipitated by an ethanol concentration of 39% (v/v) and soluble dextrans were precipitated by an ethanol concentration of 45% (v/v). The molecular weight of less soluble dextran was between MW 500,000 and 2,000,000. Soluble dextran was between 70,000 and 150,000. The molecular weight average of total dextran (50% alcohol, v/v) was between 150,000 to 500,000. The enzymatic hydrolyzates of dextrans by Penicillium or Lipomyces dextranase showed branched oligodextran series of which consisted of glucose, isomaltose, isomaltotriose, and isomaltooligosaccharides greater than DP4. References1. Seymour, F. R., and R. D. Knapp. Structural analysis of dextrans from strains of Leuconostoc and related genera that contain 3-O- α -D-glucosylated α -D-glucopyranosyl residues at the branch points, or in consecutive, linear positions (1980). Carbohydr. Res. 81, 105-129.2. Seymour, F.R., R.D. Knapp, S.H. Bishop, and A.A. Jeanes. High-temperature enhancement of 13C-NMR chemicals shift of unusual dextrans and correlation with methylation structural analysis (1979). Carbohydr Res. 68, 123-140. 3. Mehvar, R. Dextrans for targeted and sustained delivery of therapeutic and imaging agents (2000). J. Control. Release 69, 1–25.