ARS | Publication request: The production of glucans via glucansucrases by Lactobacillus satsumensis isolated from a fermented beverage starter culture

Submitted to: Applied Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 19, 2012
Publication Date: December 10, 2012
Citation: Cote, G.L., Skory, C.D., Unser, S.M., Rich, J.O. 2012. The production of glucans via glucansucrases by Lactobacillus satsumensis isolated from a fermented beverage starter culture. Applied Microbiology and Biotechnology. DOI: 10.1007/s00253-012-4606-y.

Interpretive Summary: Fermented beverages that rely on mixed yeast and bacterial cultures to ferment sugar are known world-wide, under such names as water kefir, sugary kefir, ginger beer, or tibi. The bacteria associated with these cultures usually include lactic acid bacteria which produce water-insoluble gels. Very little is known about these gels, including their chemical makeup. We screened a number of water kefir starter cultures, and isolated an unusual strain of Lactobacillus from one. This strain made copious amounts of gel from sugar. We studied the gel and found that it is very similar to gels we have been studying for the production of films, fibers, and other commercially interesting applications. This may represent a food-grade source of gelling or encapsulating polymers for the food, flavor or pharmaceutical industries. It should also help us understand the so-called probiotic health benefits of such fermented foods.

Technical 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. This strain produced at least two a-D-glucans from sucrose. One was a water-soluble dextran, consisting of predominantly a(1'6)-linked D-glucose units, and the other was a water-insoluble glucan containing both a(1'6)-linked and a(1'3)-linked D-glucose units in nearly equal proportion. 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 when the bacteria were grown on glucose, fructose, or raffinose as the carbon source.