A new process for the production of clinical dextran by mixed-culture fermentation of Lipomyces starkeyi and Leuconostoc mesenteroides.

A mixed-culture fermentation system was designed for the production of size-limited dextrans. This process was simpler and more economical than traditional methods. It required the establishment of microbial consortia of Lipomyces starkeyi ATCC 74054 and Leuconostoc mesenteroides ATCC 10830. Controlling initial conditions, growth, and enzyme production by both organisms controlled the product size. In this process, both strains were grown separately and then mixed. Dextran fermentation was then allowed to proceed. At the desired time (and molecular size), the fermentation was harvested. The optimum pH and temperature for production of clinical dextran (75,000 MW) were 5.2 (+/- 0.1) and 28 (+/- 0.5) degrees C, respectively. Varying the ratio of L. mesenteroides to L. starkeyi in the inoculum did not significantly affect either the final cell ratios or dextran production.