Biocatalytic production of extracellular exopolysaccharide dextran synthesized by cells of Leuconostoc mesenteroides

Abstract

Results are presented from studies and a comparative analysis of the production of the commercially important product dextran from sucrose using fed-batch cultivated cells of the Leuconostoc mesenteroides subsp. dextranicum B-5481 bacterium either immobilized in a polyvinyl alcohol (PVA) cryogel or in the form of a suspension. It is shown that under identical process conditions, the concentration of dextran is 1.2 times higher when using immobilized cells instead of free cells. The high productivity of dextran formation (4.2 g/(L h)) under the conditions of fed-batch cultivation of the immobilized cells and the ability of these cells to function without losing their metabolic activity for at least five operating cycles are demonstrated. The productivity of the developed biocatalyst is 5 times higher than that of Weissella confusa cells immobilized in a calcium alginate gel and 34 times higher than that of Leuconostoc mesenteroides KIBGE HA1 cells immobilized in a polyacrylamide gel. The molecular weight of the dextran samples produced by the immobilized L. mesenteroides B-5481 cells is half that of the polymer produced by the free cells, expanding the range of possible applications of the polysaccharide with no additional hydrolysis.