Cell Wall Rhamnan in Actinobacteria of the Genus Curtobacterium

Presence of the cell wall glycopolymer rhamnan was established for members of the genus Curtobacterium (family Microbacteriaceae) by using chemical and NMR spectroscopic methods. The rhamnan with the repeating unit, →2)-α-L-Rhap-(1→3)-α-L-Rhap-(1→, was found in C. flaccumfaciens pv. flaccumfaciens VKM Ас-1923T, C. flaccumfaciens pv. poinsettiae VKM Ас-1924T, C. pusillum VKM Ac-2099T, C. herbarum VKM Ac-2512T, and Curtobacterium sp. VKM Ac-1811. Each of the studied strains also contained a second, acidic phosphate-free polysaccharide. NMR spectra of these polysaccharides differed, indicating the structural differences. Cell wall hydrolysates of all studied strains were found to contain rhamnose, mannose, glucose, galactose, and glucosamine. Further research will facilitate more detailed characterization of the composition of cell wall glycopolymers in Curtobacterium species, as well as evaluation of their taxonomic significance. The data on the polymer structure will contribute to understanding of the mechanisms of colonization and infection of higher organisms by Curtobacterium species and bacterial interaction in microbial communities and with abiotic environmental objects.