Production of Dextran by Newly Isolated Strains of Leuconostoc mesenteroides PCSIR-4 and PCSIR-9

Different isolated strains of Leuconostoc mesenteroides produce dextran compared with that of L. mesenteroides NRRL B-512 F. Among nine newly isolated strains, strains PCSIR-4 and PCSIR-9 produced dextran of different quality. Using these two newly isolated strains, the development of dextran coincided closely with the disappearance of sucrose. The yield of dextran increased during growth and maximum yield was obtained at the end of exponential phase. Dextran yield was higher in media containing nitrogen source supplemented with different salts. Medium 2 was found to be best for the dextran production as compared with other media. Initial sucrose concentration in the media plays an important role in dextran production. The higher the initial concentration of sucrose in the medium, the higher is the yield of dextran produced per unit volume; however, the percentage conversion of sucrose into dextran decreases after reaching maxima. A 10% sucrose concentration in the medium was the optimal level of dextran production. Molecular mass distribution of dextran from PCSIR-4 is near to 2 million Dalton whereas the dextran produced by PCSIR-9 is quiet higher than the dextran from PCSIR-4.