Production and properties of a dextransucrase from Leuconostoc mesenteroides IBT-PQ isolated from 'pulque', a traditional Aztec alcoholic beverage

Dextransucrase was produced from a Leuconostoc mesenteroides isolated from pulque, a traditional Aztec alcoholic beverage produced from agave juice containing sucrose as the main carbon source. Almost all the dextransucrase activity (87%) was associated with the cells, and was unusually high (1.04 U mg(-1) of cells). The culture medium composition was optimized through a Box-Behnken method resulting in a process yielding 2.2 U ml(-1) of insoluble glucosyltransferase activity. The enzyme had a molecular weight of 166 kDa, Optimal temperature was 35 degrees C with a half-life of 137 min at the same temperature. As with dextransucrase from the industrial strain L. mesenteroides NRRL B-512F, the enzyme showed Michaelis-Menten kinetic behavior with excess substrate inhibition (K-m and K-i values of 0.026 M and 1.23 M respectively); produced soluble linear dextran with glucose molecules linked mainly in alpha(1-6) with branching in alpha(1-3) in a proportion of 4:1 as shown by NMR studies; and produced a high yield of isomalto-oligosaccharides in the presence of maltose.