Bacterium Leuconostoc mesenteroides Dextran

Sucrose is subjected to the action of the bacterium Leuconostoc mesenteroides B 512 and the crude, high-molecular weight dextran thus formed is hydrolyzed and fractionated to an average molecular weight of about 40,000 as measured by light-scattering techniques. 

VedyashkinaTA, RevinW, Gogotov IN. Optimizing the conditions of dextran synthesis by the bacterium Leuconostoc mesenteroides grown in a molasses-containing medium. Appl Biochem Microbiol 2005 41 361-4. 

Dextran Microbial (bacterium Leuconostoc mesenteroides) a-(l/6)-linked d-glucose residues with some degree of branching via a-(l/3) linkages. [36]... 

Homopolysaccharides are synthesised by relatively few spedfic enzymes and are not constructed from subunits. The commerdally important homo polymer dextran is synthesised extracellularly by the enzyme dextransucrase. In Leuconostoc mesenteroides the enzyme is induced by the substrate sucrose. This is deaved to release free fructose and link the glucose to the redudng end of the acceptor dextran chain, which is bound to the enzyme. The product from this bacterium is composed almost exdusively of... 

The extracellular dextran, native DP 30000-250000, produced by Leuconostoc mesenteroides, which contains largely a-(1 6) linkages (the proportion of other linkages varying with the strain) is industrially important. L. mesenteroides is an environmental bacterium, first isolated from sauerkraut. 

In the nineteenth century, there were reports of a mysterious thickening and sometimes gelling of cane and beet sugar solutions. Pasteur [148] reported in 1861, that these viscous fermentations of sucrose resulted from microbial action. Sucrose solutions were observed to be converted into viscous solutions, gels, and/or flocculent precipitates [149]. The material that produced such changes in the sucrose solutions was isolated and found to be a polysaccharide that was called dextran [150]. Van Tieghem isolated and named the bacterium that produced the polysaccharide, Leuconostoc mesenteroides [151]. 

---