No abstract

DNA and extracellular polysaccharide (EPS) analyses were performed on 14 strains of Bacteroides ruminicola. The guanine-plus-cytosine (G+C) base contents, determined from the buoyant densities of chromosomal DNAs, showed a broad range of values, from 37.6 to 50.9 mol%. DNA hybridization showed generally low DNA relatedness among the strains. Seven strains formed two groups of closely related bacteria consisting of five (group 1) and two (group 2) strains, and another strain, E42g, showed moderate relatedness to group 1 strains. However, the remaining six strains were not related to any of the other strains. DNA reassociation indicates that the strains constitute a genetically diverse group representing as many as nine separate species. EPS analysis showed that the strains produced EPS with rather uniform sugar compositions, which did not correlate with strain relationships determined by DNA analysis. Four strains had EPS with acidic sugars or unknown compounds. The EPS of strain 20-63 contained the unusual acidic sugar 4-O-(1carboxyethyl)-rhamnose. This monosaccharide has been shown to occur in nature in only one other bacterial species.

The capsular polysaccharide from Butyrivibrio fibrisolvens strain X6C61 has been investigated using NMR spectroscopy, mass spectrometry, methylation analysis, and partial acid hydrolysis as the main methods. The polysaccharide is composed of hexasaccharide repeating units having the following structure. [formula: see text] The polysaccharide also contains O-acetyl groups, of which approximately 70% are substituted to O-3 of the beta-D-Glc pA residue.

Methods for the detection, quantitation, and configurational analysis of altrose in bacterial polysaccharides were developed and are described. Thin layer chromatography (TLC) is first used to qualitatively detect altrose and other monosaccharides in polysaccharide hydrolysates. Alditol acetates are then prepared from these hydrolysates and analyzed by either gas‐liquid chromatography (GLC) or GLC‐mass spectroscopy (GLC‐MS), depending on the nature of the constituent sugars. These data allow the calculation of either the relative or absolute neutral sugar composition (using an internal standard) of a given polysaccharide. The absolute configuration of altrose and other constituent sugars in bacterial polysaccharides was easily determined by GLC analysis of acetylated diastereomeric glycosides prepared from chiral (−)‐2‐octanol and polysaccharide hydrolysates. Extracellular polysaccharides (EPS) produced by Butyrivibrio fibrisolvens were analyzed by these techniques, and we report here that l‐altrose was found in the EPS from five different strains of this organism.