Screening of 14 Lactic Acid Bacteria for Fermentative Isomalto/Malto-Polysaccharide Synthesis

Some lactic acid bacteria such as Limosilactobacillus reuteri or Fructilactobacillus sanfranciscensis contain genes encoding 4,6-α-glucanotransferases. These enzymes convert starch and maltodextrins into isomalto/malto-polysaccharides (IMMPs). Many studies focused on the properties of recombinant glucanotransferases, but limited knowledge is available on fermentative synthesis. However, this aspect would be important for the in situ IMMP formation in fermented foods such as sourdough. Therefore, the aim of this study was to investigate the IMMP synthesis of 14 different lactic acid bacteria. We demonstrated that 11 of the investigated strains formed IMMPs with varying structural compositions from different maltodextrins. The portions of α-1,6-linkages depended on the bacterial strain and composition of the maltodextrin. By using different analytical approaches, it was demonstrated that linear chains of α-1,6-linked glucopyranoses with varying lengths were formed. Thus, the 11 IMMP-producing strains have high potential for an in situ synthesis of IMMPs in fermented foods such as sourdough.