Novel Rhamnose-Containing Glycopolymers from the Cell Wall of Rathayibacter festucae VKM Ac-1390T

<i>Rathayibacter festucae</i> VKM Ac-1390^T (family Microbacteriaceae, class Actinomycetes) contains three rhamnose-containing glycopolymers in the cell wall, the structures of which were established by chemical and NMR spectroscopy methods. The first polymer, a rhamnomannan, consists of repeating tetrasaccharide units with xylopyranose side residues, →2)-α-[β-D-Xyl<i>p</i>-(1→3)]-D-Rha<i>p</i>-(1→3)-α-D-Man<i>p</i>-(1→2)-α-D-Rha<i>p</i>-(1→3)-α-D-Man<i>p</i>-(1→. The second polymer found in minor amounts, is a rhamnan, →2)-α-D-Rha<i>p</i>-(1→3)-α-D-Rha<i>p</i>-(1→. The third polymer is a teichuronic acid acetalated with pyruvic acid, →2)-α-[4,6-<i>S</i>-Pyr]-D-Man<i>p</i>-(1→4)-α-L-Rha<i>p</i>-(1→4)-β-D-Glc<i>p-</i>(1→4)-α-D-Glc<i>p-</i>(1→4)-β-D-Glc<i>p</i>A<i>-</i>(1→. The structures of rhamnomannan and teichuronic acid are new for <i>Ratayibacter</i> and prokaryotes in a whole. The results of this study expand our understanding of the structural diversity of microbial glycopolymers and are consistent with previous reports on the species specificity of glycopolymer structures and composition in the genus <i>Rathayibacter.</i>