We have examined the diversity of glycoconjugates and cellular lipids of Rhizobium ''hedysari'' IS123, a bacterial symbiont that specifically nodulates the drought-tolerant forage legume Hedysarum coronarium. IS123 develops a complete capsule consisting of a loose fibrillar network of ruthenium-red-staining acidic polymers and produces two different exopolysaccharides (EPS). EPS-A contains glucose, galactose, mannose, and a noncarbohydrate substitution tentatively identified as a lactyl ester. The composition of EPS-B, which includes glucose and galactose, as well as O-acetyl, pyruvyl, and succinyl substituents, is very similar to that of the EPS-II described in Rhizobium meliloti. IS123 also makes an O-acetylated heterooligosaccharide and unsubstituted beta-1,2-glucans. The cellular fatty acid composition of IS123 is dominated by 18:1 and also includes 14:0, 16:0, 16:1, 3OH-16:0, 17:0 Delta, 18:0, 3OH-18:0, and 19:0 Delta. Phospholipids of IS123 include phosphatidylethanolamine, N-methyl phosphatidylethanolamine, N,N-dimethyl phosphatidylethanol amine, phosphatidylcholine, and phosphatidylglycerol.
