Mutagenesis of specific amino acid residues of the glucansucrase (GTF180) enzyme from Lactobacillus reuteri strain 180 yielded 12 mutant enzymes that produced modified exopolysaccharides (mEPSs) from sucrose. Ethanol-precipitated and purified mEPSs were subjected to linkage analysis, Smith degradation analysis, and 1D/2D H-1 NMR spectroscopy. Comparison of the results with structural data of the previously described wild type EPS180 and triple mutant mEPS-PNNS revealed a broad variation of structural elements between mEPS molecules. The amount of (alpha 1 -> 3) linkages varied from 14-43%, the amount of (alpha 1 -> 4) linkages (not present in the wild type) from 0-12%, and the amount of (alpha 1 -> 6) linkages from 51-86%. The average molecular weight (M-w) ranged from 9.4 to 32.3 MDa and the degree of branching varied from 8-20%. Using a previously established H-1 NMR structural-reporter-group concept, composite models, that include all identified structural features, were formulated for all mEPS molecules. Variations in the mEPS structures strongly affected the physical properties of the mEPSs.