A Comparison of the Surface Polysaccharides from Rhizobium leguminosarum 128C53 smrrifr with the Surface Polysaccharides from Its Exo−1 Mutant

Publisher Website
Google Scholar
Abstract
The surface polysaccharides of R. leguminosarum 128C53 smrrifr (parent) and its exo-1 mutant were isolated and characterized. The parent carries out normal symbiosis with its host, pea, while the exo-1 mutant does not nodulate the pea. The parent produces lipopolysaccharide (LPS), typical acidic extracellular polysaccharide (EPS) and 3 additional polysaccharides, PS1, PS2 and PS3. The PS1 and PS2 fractions are likely to be the capsular polysaccharide (CPS) and are identical in composition to the EPS. The PS3 fraction is a small MW glucan. The exo-1 mutant produces LPS, EPS and a PS3 fraction, but does not produce significant amounts of PS1 or PS2. The LPS from the exo-1 mutant appears to be identical to the parental LPS. Analysis of the EPS from exo-1 shows that it consists of 2 polysaccharides. One polysaccharide is identical to the LPS and comprises 70% of the exo-1 EPS. The second polysacchairde is identical to the exo-1 PS3 and comprises 30% of the exo-1 EPS. The exo-1 mutant does not produce any of the typical acidic parental EPS and the major polysaccharide released into the media by the exo-1 mutant is intact LPS. The exo-1 mutant PS3 fraction contains 2 polysaccharides, PS3-1 and PS3-2. the PS3-2 polysaccharide is identical to the parental PS3 described above. The PS3-1 polysaccharide has a composition similar to the polysaccharide portion of the LPS. The exo-1 mutant may produce LPS polysaccharide fragments. These LPS polysaccharide fragments are not produced by the parent strain.