The human gastrointestinal tract is colonized by trillions of microorganisms, discovery of sugar structure and sequence of polysaccharides on the surface of these microorganisms will provide the structural foundation to understanding the biological functions of human gut microbiota. Since majority of human gut microbiota cannot be cultured, current metabolic glycan-labeling methods may not be used for for analyzing surface monosaccharides of gut microbiota. Here we will discuss two approaches to discover specific monosaccharide or oligosaccharide sequences on the surface of human gut microbiota. For identification of gut microbiota bearing specific monosaccharide, the corresponding lectin-coupled magnetic beads were used to first screen and isolate the microorganisms with the specific monosaccharide on the surface. This was followed by 16S rRNA gene sequencing to identify and characterize the isolated microorganisms. For example, Griffonia simplicifolia lectin I (GSL I), which binds specifically to terminal α-galactose and α-N-acetylgalactosamine residues of cells, was used for characterizing microorganism with surface α-Gal and α-GalNac in human gut microbiota. For identification of gut microbiota bearing specific carbohydrate sequences, we used specific antibody-coupled magnetic beads to isolate those microorganisms. For example, we identified gut microbiota with human A or B blood group antigen in the surface with human anti-A and anti-B antibodies. Currently, we are using a number of glycosyltransferases to label specific glycol sequences on the surface of bacteria with a monosaccharide containing a tag. These labeled bacteria can be isolated and sequenced for characterization. In summary, several approaches are being developed and used for high-throughput identification of human gut microbiota containing specific monosaccharide or oligosaccharide sequences.

High-throughput identification of human gut microbiota containing specific monosaccharide or oligosaccharide sequences

ACS Fall 2020 Virtual Meeting

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