A polyglucose biopolymer characterized by preponderance of α-1,6 linkage, and generally produced by enzymes from certain strains of Leuconostoc or Streptococcus. The chemical properties may be modified chemically for specific usages. While formerly its principal utility was as blood plasma substitute, dextran is also employed as packing material in column chromatography and as pharmaceutical agents; its average molecular weight determines usage to a great extent. Dextran's chemical and physical properties depend upon the strain of microorganism employed and the environmental conditions imposed upon the bacterium during growth, or the reaction conditions where an enzymatic method of dextran production is employed. Leuconostoc and Streptococcus species primarily convert sucrose to dextran and fructose. Acetobacter species convert dextrin to dextran; the α-1,4 linkage is converted to an α-1,6 linkage.