Optimization of conditions for the efficient production of mutan in streptococcal cultures and post-culture liquids.

The strain Streptococcus sobrinus CCUG 21020 was found to produce water-insoluble and adhesive mutan. The factors influencing both stages of the mutan production, i.e. streptococcal cultures and glucan synthesis in post-culture supernatants were standardized. The application of optimized process parameters for mutan production on a larger scale made it possible to obtain approximately 2.2 g of water-insoluble glucan per 11 of culture supernate--this productivity was higher than the best reported in the literature. It was shown that some of the tested beet sugars might be successfully utilized as substitutes for pure sucrose in the process of mutan synthesis. Nuclear magnetic resonance analyses confirmed that the insoluble biopolymer synthesized by a mixture of crude glucosyltransferases was a mixed-linkage (1-->3), (1-->6)-alpha-D-glucan (the so-called mutan) with a greater proportion of 1,3 to 1,6 linkages.