A rapid NMR-based method for discrimination of strain-specific cell wall teichoic acid structures reveals a third backbone type in Lactobacillus plantarum

Abstract

The lactic acid bacterium Lactobacillus plantarum is capable of producing strain-specific structures of cell wall teichoic acid (WTA), an anionic polysaccharide found in the Gram-positive bacterial cell wall. In this study, we established a rapid, NMR-based procedure to discriminate WTA structures in this species, and applied it to 94 strains of L. plantarum. Six previously reported glycerol- and ribitol-containing WTA subtypes were successfully identified from 78 strains, suggesting that these were the dominant structures. However, the level of structural variety differed markedly among bacterial sources, possibly reflecting differences in strain-level microbial diversity. WTAs from eight strains were not identified based on NMR spectra and were classified into three groups. Structural analysis of a partial degradation product of an unidentified WTA produced by strain TUA 1496L revealed that the WTA was 1-O-β-d-glucosylglycerol. Two-dimensional NMR analysis of the polymer structure showed phosphodiester bonds between C-3 and C-6 of the glycerol and glucose residues, suggesting a polymer structure of 3,6'-linked poly(1-O-β-d-glucosyl-sn-glycerol phosphate). This is the third WTA backbone structure in L. plantarum, following 3,6'-linked poly(1-O-α-d-glucosyl-sn-glycerol phosphate) and 1,5-linked poly(ribitol phosphate).