Sugar composition of lipopolysaccharides of family Vibrionaceae. Absence of 2-keto-3-deoxyoctonate (KDO) except in Vibrio parahaemolyticus O6

A comparative study was carried out on the sugar composition of lipopolysaccharides (LPS) isolated from representative strains of members of the family Vibrionaceae including all of the constituting genera, i.e., Vibrio, Aeromonas, Photobacterium, Plesiomonas , and Lucibacterium . More than 100 strains were examined. It was found that, with the exception of Vibrio parahaemolyticus 06, 2‐keto‐3‐deoxyoctonate (KDO), known generally as a component sugar in the core region of usual gram‐negative bacterial LPS, is virtually absent from LPS of the Vibrionaceae strains so far examined. Furthermore, mannose was also lacking in LPS of Vibrionaceae strains with the exception of only one strain, A. anaerogenes (ATCC 15467). Instead, some KDO‐like substances were found in LPS from Vibrio ( “Beneckea” ) nereida (ATCC 25917) and Plesiomonas shigelloides including the type strain (ATCC 14029), the same as those found in LPS from V. parahaemolyticus O7 and O12, and three strains of V. alginolyticus . These substances were strongly positive in the periodate‐thiobarbituric acid test, yielding a color with maximum absorption at 549 nm. The spectra were identical to that of KDO, whereas substances differed from KDO at least in behavior in high‐voltage paper electrophoresis and thin‐layer chromatography. A particularly interesting feature from the chemotaxonomical point of view was found in the sugar composition of LPS isolated from V. cholerae . Fructose was present exclusively in LPS of V. cholerae (both O1 and non‐O1 groups and classical and eltor biotypes) with the exception of one strain of Photobacterium phosphoreum (NCMB 844). In addition, a pair of rarely occurring amino sugars, perosamine and quinovosamine, was found in LPS from O1 group V. cholerae regardless of either the biotype (classical or eltor) or the serotype (Inaba or Ogawa), whereas this pair was not present in non‐O1 group V. cholerae (the so‐called NAG vibrios). This feature was confirmed with LPS from more than 30 additional strains of O1 group V. cholerae isolated from patients. The virtual absence of KDO in LPS of the family Vibrionaceae was demonstrated for the first time in this study. These results are compatible with the interpretation that the absence of KDO in LPS can be used as one of the taxonomical characteristics of Vibrionaceae in addition to (G+C) content, DNA (or RNA) homology, and numerical analysis data.