Structural and Immunochemical Studies of the Lipopolysaccharide from the Fish Pathogen, Aeromonas bestiarum Strain K296, Serotype O18

Abstract

Chemical analyses and mass spectrometry were used to study the structure of the lipopolysaccharide (LPS) isolated from Aeromonas bestiarum strain K296, serotype O18. ESI-MS revealed that the most abundant A. bestiarum LPS glycoforms have a hexa-acylated or tetra-acylated lipid A with conserved architecture of the backbone, consisting of a 1,4′-bisphosphorylated β-(1→6)-linked d-GlcN disaccharide with an AraN residue as a non-stoichiometric substituent and a core oligosaccharide composed of Kdo1Hep6Hex1HexN1P1. 1D and 2D NMR spectroscopy revealed that the O-specific polysaccharide (OPS) of A. bestiarum K296 consists of a branched tetrasaccharide repeating unit containing two 6-deoxy-l-talose (6dTalp), one Manp and one GalpNAc residues; thus, it is similar to that of the OPS of A. hydrophila AH-3 (serotype O34) in both the sugar composition and the glycosylation pattern. Moreover, 3-substituted 6dTalp was 2-O-acetylated and additional O-acetyl groups were identified at O-2 and O-4 (or O-3) positions of the terminal 6dTalp. Western blots with polyclonal rabbit sera showed that serotypes O18 and O34 share some epitopes in the LPS. The very weak reaction of the anti-O34 serum with the O-deacylated LPS of A. bestiarum K296 might have been due to the different O-acetylation pattern of the terminal 6dTalp. The latter suggestion was further confirmed by NMR.

Structure of the O-specific polysaccharide from the lipopolysaccharide of Aeromonas sobria strain Pt312

“…16 It was found that the LPS was distributed between the water and phenol phases in yields of 2.2% and 2.8% of the dry bacterial cell mass, respectively. The SDS-PAGE profile of these two fractions revealed a pattern, in which bands of the high-molecular-mass Sform LPS species were accompanied by bands appearing in the region corresponding to a rough form of Salmonella LPS (Fig.…”

“…strains classified as belonging to different serogroups have been determined. [14][15][16] Here, we report on the structural studies of the OPS liberated from the LPS of Aeromonas sobria strain Pt312, which was isolated from a kidney of apparently healthy rainbow trout (Oncorhynchus mykiss Walbaum) during an outbreak of motile aeromonad septicemia (MAS) on a Polish trout farm. 11 …”

Draft Genome Sequence of Fish Pathogen Aeromonas bestiarum GA97-22

“… Aeromonas species are autochthonous to aquatic environments and cause disease in fish and mammals. Aeromonas hydrophila , A. veronii , A. sobria , A. caviae , and A. bestiarum species are causative agents of motile aeromonad septicemia (MAS) ( 1 – 3 ). A. bestiarum is a mesophilic motile aeromonad first described in 1996 ( 2 ), and it causes hemorrhagic septicemia and skin ulcers in fish ( 2 , 4 – 6 ).…”

Mass Spectrometry: Updates in the Elucidation of Structure of Oligosaccharides

“…4.4) [74]. ESI FT-ICR mass spectra has revealed itself to be an excellent tool to identify both smooth and rough forms of lipopolysaccharides, due to the high mass resolution (more than 50,000) and accuracy (about 1 ppm) [73,75,76]. With this powerful technique, it is possible in some cases to reveal the linkage between the core oligosaccharide and the first O-chain repeating unit [75].…”