The production of glucans via glucansucrases from Lactobacillus satsumensis isolated from a fermented beverage starter culture.

ABSTRACT

Several starter cultures used in the production of fermented beverages were screened for lactic acid bacteria that produced water-insoluble polysaccharides from sucrose. The strain producing the greatest amount was identified as Lactobacillus satsumensis by its 16S RNA sequence and was deposited in the ARS culture collection as NRRL B-59839. This strain produced at least two α-D-glucans from sucrose. One was a water-soluble dextran, consisting of predominantly α-(1 → 6)-linked D-glucose units, and the other was a water-insoluble glucan containing both α-(1 → 6)-linked and α-(1 → 3)-linked D-glucose units. The culture fluid was found to contain glucansucrases responsible for the two glucans, and no significant level of fructansucrase was detected. Glucansucrase activity was not present in the culture fluid when the bacteria were grown on glucose, fructose, or raffinose as the carbon source. Although the water-soluble glucans produced by cell-free enzyme and by cell suspensions were essentially identical, the same was not true for the water-insoluble glucans. The water-insoluble glucan produced by cell-free culture fluid contained a higher proportion of α-(1 → 3)-linked D-glucose units than the water-insoluble glucan produced by cell suspensions.