Mapping Glycan Binding Profiles of the Gut Bacteria using Liquid Glycan Array (LiGA)

Glycan-microbe interactions are central to gut colonization and host-microbiota communication. Here, we apply a DNA-encoded Liquid Glycan Array (LiGA) to quantify interactions between live gut bacteria and multivalent natural or mirror glycans. LiGA comprises glycosylated M13 bacteriophage bearing silent DNA barcodes that encode glycan identity and density. Using LiGA, we profiled glycan binding across 16 Limosilactobacillus reuteri strains isolated from murine, porcine, poultry, and human hosts, and then extended the approach to profile glycan binding of taxonomically diverse bacteria from three phyla Bacillota, Bacteroidota, Pseudomonadota consisting of nine different species. Recent discussion of mirror-image microorganisms raise a question whether these microorganisms could interact with present-day life by engaging naturally chiral glycans. We demonstrated that this question can be assessed by testing the binding of mirror-image glycans to natural bacteria. Evaluation of enantiomers of common glycan revealed cross-chiral recognition by Escherichia coli and L. reuteri, indicating that these bacteria can used mirror-image glycans to engage for adhesion and potential colonization. By symmetry the same arguments extends to mirror microorganisms and glycans of naturally chirality. We established that LiGA enables efficient characterization of bacterial glycan binding and provides new insights into intestinal microbial ecology.