Levan – as a fructose homopolymer - because of its physicochemical properties as well as physiological effect on the human organism, has been the subject of numerous research. The aim of this study was to investigate the course of the synthesis of this polymer with the addition of crude enzymatic preparation isolated from the cell-free culture liquid of the Bacillus subtilis DSM 347 bacterium. Saccharose was the donor of fructofuranosyl residues. The effects of some metal ions during synthesis were determined. The innovation in these experiments was the usage of Candida cacaoi DSM 2226 yeasts which were introduced into the dialysing membrane (situated in reaction mixture). The yeasts selectively removed glucose from the reaction media because this mono-sugar is considered as an inhibitor of levansucrase. It was found that the decrease of glucose concentration in the medium by 16-19% resulted in the increased degree of levan polymerisation (by 6 to 9%) and efficiency of levan synthesis (by 9 to 11%). The isolated preparation of levansucrase showed high stability during 140 h synthesis at 37^oC which allowed to achieve a compromise between the quantity of released glucose in time and the possibilities of Candida cacaoi DSM 2226 yeast to utilise that free glucose. The Mn²⁺ ions (at a concentration of 2.5 mmol/L) activated levansucrase (twice increased the initial transferase rate of enzyme) and in reaction medium supplemented with that metal ions the efficiency of levan synthesis increased up to 39%. Associated action of levansucrase and yeasts in the presence of Mn²⁺ effected in the increase of levan synthesis efficiency to 64%.