| 摘要 |
PROBLEM TO BE SOLVED: To provide a method or producing a low molecular weight dextran from sucrose in one step, that is, in a direct fermentation in high yield. SOLUTION: In producing dextran by culturing strains belonging to Leuconostoc mesenteroides, dextran having 4,000-700,000 weight average molecular weight is selectively produced by adding sucrose and a dextran precursor in an addition ratio to be able to obtain dextran having the prescribed weight average molecular weight. This method of the invention is suitable for producing dextran having a weight average molecular weight from several thousands to several hundred thousands and has a merit to be able to obtain dextran having an arbitrary molecular weight in very high yield by adjusting the molecular weight of a precursor dextran and ratio of the precursor and sucrose. The productivity can be greatly enhanced, as the process is simpler and more efficient compared with usual processes, e.g. the process is performed fin one step and requires no fractionation treatments such as those using ultrafiltration membranes, owing to the narrow molecular weight distribution of the produced dextran. |
