Production and characterization of dextransucrase from newly isolated strain of leuconostoc mesenteroides EA-6

Dextransucrase (EC 2.4.1.5) from Leuconostoc mesenteroides species catalyzes the formation of dextran by transfer of the glucosyl moieties of sucrose to a growing chain. A newly isolated strain of Leuconostoc mesenteroides EA-6 showed maximum dextransucrase production in 18 h and exhibited maximum extracellular enzyme activity in 15 min. Dextransucrase production is also affected by the sucrose concentration in the culture media. Maximum enzyme production was obtained in a medium containing 2% sucrose as a carbon source, while extracellular enzyme activity was found to be maximum at 125 mg/ml of sucrose. The optimum temperature and initial medium pH for dextransucrase production by the organism were 25°C and 7.5, respectively. The optimum pH and temperature for extracellular enzyme activity were 5.0 and 35°C, respectively. Enzyme activity was found to be maximum in 0.2 M citrate phosphate buffer. Due to the high extracellular enzyme activity, Leuconostoc mesenteroides EA-6 should be used for the elaboration of the dextransucrase on a large scale, which can allow the commercial production of dextran in cell free bioreactor.