CHAPTER 14 – DEXTRAN

Publisher Summary This chapter discusses dextrans of commercial interest and in particular, the dextran from Leuconostoc mesenteroides NRRL B-512(F). Dextran is produced in most developed countries, primarily for clinical products. Good yields of native dextran are dependent on vigorous growth of the organism, optimal elaboration of the enzyme, and efficient production of dextran. The dextran-synthesizing activity of the enzyme exhibits a maximum at pH 5.2, which is considerably lower than that for the optimal elaboration of the enzyme in culture. Although batch-wise production of dextran is the main source of native dextran, a number of alternative processes have been devised such as the use of free or immobilized cell-free enzymes, fermentations in the presence of acceptors, and continuous processes. The development of size-exclusion chromatography for dextran provides a rapid and quantitative determination of molecular size distribution. Dextran elaborated by Leuconostoc mesenteroides NRRL B-512(F) is a (1→ 6)-linked α-D-glucan with side chains attached to 0–3 of the backbone chain units. Dextrans are most likely to find application in high-quality or high-technology specialty products.