The galactoglucan from Lactiplantibacillus plantarum DSA_B is assembled from two phosphodiester-bound moieties with distinct antimicrobial and antioxidant profiles

The strain Lactiplantibacillus plantarum DSA_B bacterium is coated by a CPS whose structure consists of two moieties as determined by chemical and NMR analyses: a galactoglucan backbone 3)-α-Glc-(1→3)-β-Glc-(1→3)-β-Gal6P-(1→, with the phosphate substituted with the trisaccharide β-Galf-(1→6)-β-Glc-(1→6)-α-Gal-(1→. The intact CPS exerted antimicrobial activity against Listeria monocytogenes. Preliminary data indicate that the backbone, but not the intact CPS, delayed the growth of Salmonella enterica. These data suggest that the intact CPS and its individual moieties are associated with diverse antimicrobial profiles under the preliminary tested conditions, although the molecular basis of these effects remains to be established. Finally, the CPS showed modest DPPH scavenging potential while the opposite is observed for its components, the lateral chain and the backbone, each showing potential antioxidant activity, and with the lateral chain showing modest effect in the FRAP assay. Preliminary static in vitro digestion experiments suggested limited cleavage of the phosphodiester linkage, supporting the possibility that mixtures of intact and partially cleaved forms may coexist under digestive-like conditions. The current results suggest that the beneficial effect of this CPS can be tuned in the gut by the partial cleavage into its components, a perspective rarely considered hitherto.