Dextran was produced using immobilized cells of L. mesenteroides ATCC 10830 (NRRL SB-512F) in 3% calcium aiginate beads in absence and presence of 1% (w/v) B-cyclodextrin (B-CD). Information about the molecular structure of the produced polymers was obtained using size exclusion chromatography and on-line low angle laser light scattering (SEC/LALLS) detection. Addition of B-CD to the dextran production medium led to a drastic change in the structure of the produced dextran. Branching of the produced polymer in presence of ß-CD was drastically increased and possibly produced a star-like polymer containing B-CD in the center with different dextranyl residues attached to its primary or secondary hydroxyl groups.resolution.