Role of bacterial polysaccharides in the adsorption process of the Rhizobium-Pea symbiosis.

cowpea, where the adsorption of strain 102F51 was similar to that of strain 3G4bI6. The initial adsorption rates of bacteria cultured in synthetic media and in the presence of soybean roots were about the same. Addition of soybean lectin to the bacterial inoculum failed to influence initial adsorption rates. Both treatments, however, reduced the numbers of bacteria that bound after incubation with roots for 120 minutes. The relationship between the logarithm of the number of strain 138 cells bound per soybean root segment and the logarithm of the density of bacteria in the inoculum was linear over filve orders of magnitude. Binding of strain 138 to soybean roots was greatest at room temperature (27°C) and substantially attenuated at both 4 and 37°C. Although R. lupini 96B9 strongly rejected a model hydrophobic plastic surface, there were no simple correlations between bacterial binding to model hydrophobic and hydrophilic plastic surfaces and bacterial adsorption to roots.

supporting

confidence: 55%

Section: Resultsmentioning

confidence: 79%

See 1 more Smart Citation

Adsorption of Slow- and Fast-Growing Rhizobia to Soybean and Cowpea Roots

Pueppke

1984

“…Bacterial polysaccharide fractions purified in a similar manner to PSI and PS2 have been reported as CPS (11,12,16,25). The major polysaccharide recovered in the saline wash of Rhizobium has been reported to be CPS for both R japonicum (12) and R leguminosarum strains (11). The major polysaccharide in the ultracentrifuge supernatant of the phenol:water water layer from many Escherichia coli strains has been shown to be CPS (16,25).…”

Section: Discussionmentioning

confidence: 98%

A Comparison of the Surface Polysaccharides from Rhizobium leguminosarum 128C53 sm^rrif^r with the Surface Polysaccharides from Its Exo⁻¹ Mutant

Carlson¹,

Lee²

1983

The surface polysacchandes of Rhizobiun kgwnisarwn 128(53 smrrifr (parent) and its exo-1 mutant were isolated and characterized. The parent carries out normal symbiosis with its host, pea, while the exo1 mutant does not nodulate the pea. The following observations were made. (a) The parent produces lipopolysaccharide (LPS), typical acidic extracellular polysaccharide (EPS), and three additional polysaccharides, PSI, 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 smallmolecular-weight glucan. (b) The exo-1 mutant produces LPS, EPS, and a PS3 fraction, but does not produce significant amounts of either PSI or PS2. The LPS from the exo-1 mutant appears to be identical to the parental LPS. Analysis of the EPS from exo-' shows that it consists of two polysaccharides. One polysaccharide is identical to the LPS and comprises 70% of the exo-' EPS. The second polysaccharide is identical to the exo-1 PS3 and comprises 30% of the exo-1 EPS. This result shows that the exo-' mutant does not produce any of the typical acidic parental EPS and that the major polysaccharide released into the media by the exo-1 mutant is intact LPS. The exo-1 mutant PS3 fraction was found to contain two polysaccharies, PS3-I 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. This result suggests that the exo-1 mutant produces LPS polysaccharide fragments. These LPS polysaccharide fragments are not produced by the parent strain.There are many reports which implicate a role for the surface polysaccharides of rhizobia in determining the specificity of Rhizobium-legume symbiosis (for a recent review, see 3). In this report, we compare the surface polysaccharides from Rhizobium leguminosarum 128C53 smrrifr3 (jarent) the host, pea.There have been several reports concerning the polysaccharides of R leguminosarum 128C53 and some of its mutants. An early report shows that the exo-1 mutant produces about 4% of the EPS in comparison to the parent (20). In addition, it is reported that the exo-1 LPS has a very similar structure to the parental LPS (20). It was suggested that the diminished production of EPS is related to the inability of the mutant to nodulate its host (20). A subsequent report presents data which show that the exo-' mutant produces about 1.5% of the parental EPS, that it does not form Shepherd's crook root hair curls, it does not form infection threads, and it does not nodulate the host (15). Additionally, the exo-1 mutant does not appear to attach to the host root (C. Napoli, personal communication). Several other EPS-deficient mutants were analyzed for their symbiotic properties and the data indicate that there is a correlation between the ability of the mutant to produce a capsule, as visualized by the India ink staining procedure, and the ability to nodulate the host (15). The exo-mutant w...

“…One of these reports (12) suggests that the LPS from early stationary phase R. trifolii cells binds the clover lectin, trifoliin, to a greater extent than the LPS from exponentially growing cells. It has also been reported that the LPS, as well as CPS, from Rhizobium leguminosarum inhibit the binding of these bacteria to the host root (15). Differences in the composition between the LPSs from nodulating and nonnodulating mutants of R. trifolii have been reported (21).…”

Section: Abstracirmentioning

confidence: 98%

The Isolation and Partial Characterization of the Lipopolysaccharides from Several Rhizobium trifolii Mutants Affected in Root Hair Infection

Carlson¹,

Shatters²,

Duh³

et al. 1987

ABSTRACIrThe lipopolysaccharides (LPSs) from Rhizobium trifolii ANU843 and several transposon (Tn5) symbiotic mutants derived from ANU843 were isolated and partially characterized. The mutant strains are unable to induce normal root hair curling (Hac-phenotype) or nodulation (Nodphenotype) in clover plants. The LPSs from the parent and mutants are very similar in composition. Analysis by PAGE shows that the LPSs consist of higher and lower molecular weight forms. The higher molecular weight form of the LPSs exists in several aggregation states when PAGE is done in 0.1% SDS but collapses into a single band when PAGE is done in 0.5% SDS. Mild acid hydrolysis of all the LPSs releases two polysaccharides, PS1 and PS2. Immunoblots of the PAGE gels and enzyme linked immunosorbant assay inhibition assays show that the PS1 fractions contain the immunodominant sites of the LPSs and that these sites are present in the higher molecular weight form of the LPSs. All the PS1 fractions contain methylated sugars, 2-amino-2,6-dideoxyhexose, heptose, glucuronic acid, and 2-keto-3-deoxyoctonic acid (KDO). All the PS2 fractions contain galacturonic acid, mannose, galactose, and KDO. The PS2 fractions have a molecular weight of about 700. The KDO is present at the reducing end of both the PS1 and the PS2 fractions. The PSI and PS2 fractions from the mutants contain more glucose than these fractions from the parent. The LPS from a deletion mutant contains less acyl groups than the other LPSs. Immunoblots of the LPSs show that the parent and nod A mutant LPSs contain an additional antigenic band which is not observed in the other LPSs.Rhizobia are gram-negative bacteria which form a nitrogenfixing symbiotic relationship with legume plants. As gram-negative bacteria they have the usual surface polysaccharides consisting of EPSs,6 CPSs, and LPSs. All of these molecules have been 'Funded by a grant from the National Science Foundation (DCB8406697).