Dextransucrase production from Leuconostoc mesenteroides NRRL B-5 12F was carried out in batch cultures under different conditions in static culture conditions. Small changes in the temperature had a significant effect on the enzyme production. A temperature of 23 "C gave the maximum yield of the enzyme. An increase in the temperature to 25 "C reduced the enzyme activity by 28%, while a decrease in the temperature to 20 "C caused 17% reduction. Static flask culture favored the dextransucrase production as compared to the shaken flask culture. The enzyme activity in the static flask was 30% higher than the activity in rotary shaken flask culture. The dextransucrase was purified by three successive steps of precipitation using PEG 400. Purified dextransucrase exhibited maximum activity at 30 "C, pH 5.2 and 10% of the substrate sucrose. Among the various stabilizers used (glycerol, PEG 8000, dextran and tween 80), glycerol provided maximum stability to the enzyme against the activity losses at temperatures 0 "C and 30 "C.
Dextransucrase [Sucrose: 1 , 6 -a -~ glucan 6 -a -~ glucosyl transferase, EC 2.4.1 S } belonging to the group of enzymes called glucosyltransferases catalyzes the formation of dextran from sucrose.
~t SUCROSE + DEXTRAN + n FRUCTOSE Dextransucrase synthesizing bacteria belong to the genera Luctobacillus, Leuconostoc and Streptococcus. The most extensively studied dextransucrase is, that elaborated by Leuconostoc mesenteroides NRRL B-512F. The enzyme dextransucrase produced by this strain is industrially important, because its product, the soluble dextran, has many industrial and medical applications (ROBYT 1986). Dextransucrase is an inducible enzyme and its substrate sucrose, the only known inducer of enzyme synthesis (NEELY and N o n 1962), is used by the bacterium as a carbon source for growth and also as a substrate for the synthesis of dextran.
A number of reports are available on the production of dextransucrase under different culture conditions using different enzyme production media and the temperatures in the range 20 to 30 "C have been used for dextransucrase production by various workers (AJONGWEN and