Chemical structure of lipoteichoic acid in the probiotic strain Latilactobacillus curvatus CP2998.

Latilactobacillus curvatus, found in various fermented foods, is a promising probiotic with unique health benefits. Lipoteichoic acid (LTA) is a characteristic amphiphilic surface polymer of gram-positive bacteria and exhibits immunomodulatory activities. Despite the structural diversity of LTA among different bacterial species and strains, no information is available on the chemical structure of LTA in L. curvatus. In this study, we aimed to determine the structure of LTA isolated from L. curvatus CP2998. One- and two-dimensional nuclear magnetic resonance spectra of intact LTA revealed that LTA had a glycerolphosphate polymer as a hydrophilic main chain with partial substitutions of α-linked glucose and D-alanine at the hydroxy group at position 2 of the glycerol residue. The anchor glycolipid fraction was obtained by hydrofluoric acid treatment. Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry spectrum of the anchor glycolipid revealed that it contained diglucosyldiacylglycerol and diglucosylmonoacylglycerol. Our results suggest that L. curvatus CP2998 possesses a typical type I LTA structure; however, the lactic acid bacteria-specific anchor glycolipid structures, such as tri- or tetra-saccharides and three fatty acid residues, were not identified.