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PubMed1963

DECOMPOSITION AND BINDING ACTION OF A POLYSACCHARIDE FROM CHROMOBACTERIUM VIOLACIUM IN SOIL.

Martin, J. P. (University of California, Riverside) and S. J. Richards. Decomposition and binding action of a polysaccharide from Chromobacterium violaceum in soil. J. Bacteriol. 85:1288-1294. 1963.-The decomposition rate and binding effect in soil of a polysaccharide from Chromobacterium violaceum was compared with that of a variety of bacterial and plant polysaccharides and more complex organic residues. Most of the polysaccharides tested decomposed more readily than mature plant residues and fungus mycelium. The ease of decomposition varied, however, and polysaccharide from C. violaceum over a period of 1 month was more resistant than corn stalks, Rhodes grass, bean straw, and orange leaves. During the first week, it was as resistant to decay as pine needles. The C. violaceum polysaccharide was more effective in binding or aggregating the soil than all others tested. It also reduced the bulk density of Greenfield sandy loam and increased hydraulic conductivity in neutral soil.

Chromobacterium↗

PubMed1964

CAPSULAR POLYSACCHARIDE OF AZOTOBACTER AGILIS.

Cohen, Gary H. (University of Vermont, Burlington), and Donald B. Johnstone. Capsular polysaccharide of Azotobacter agilis. J. Bacteriol. 88:1695-1699. 1964.-Capsular polysaccharide from Azotobacter agilis strain 132 was recovered from washed cells by alkaline digestion. The polysaccharide was purified by centrifugation, repeated alcohol precipitation, Sevag deproteinization, and treatment with ribonuclease and charcoal-cellulose. Methods of isolation and purification appeared to provide a polymer showing no evidence of heterogeneity when examined by chemical and physical methods. Colorimetric, paper chromatographic, and enzymatic analyses on both intact and acid-hydrolyzed polysaccharide indicated that the polymer contained galactose and rhamnose at a molar ratio of approximately 1.0:0.7. A sialic acid-like component was also present in the polysaccharide. The study shows significant differences in the chemical composition of the extra-cellular polysaccharide of A. agilis and that of A. vinelandii. This adds further biochemical evidence for the right of these species to independent status.

Azotobacter↗

PubMed1994

Partition of polysaccharide-coated liposomes in aqueous two-phase systems.

Hydrophobized polysaccharides such as cholesterol-bearing pullulan (CHP), dextran (CHD) and mannan (CHM) effectively coat the liposomal surface. Partition of the hydrophobized polysaccharide-coated liposomes in an aqueous two-phase system (PEO (top)/pullulan (bottom) or PEO (top)/dextran (bottom)) was investigated (PEO = poly(ethylene oxide)). Conventional liposomes without a polysaccharide coat mostly locate at the interface between the two polymer phases. The polysaccharide-coated liposomes, on the other hand, were partly partitioned to the bottom polysaccharide phase depending on the structure of the hydrophobized polysaccharide on the liposomal surface. The affinity between the polysaccharide on the liposomal surface and that in the bulk bottom phase controls the efficiency of partition. The sequence of interaction strength between the two carbohydrates was the following: for the PEO/dextran two-phase system, dextran(liposome)-dextran(bulk) > mannan(liposome)- dextran(bulk) > pullulan(liposome)-dextran(bulk); while for the PEO/pullulan system, the sequence of interaction strength was pullulan(liposome)- pullulan(bulk) > dextran(liposome)-pullulan(bulk) approximately mannan(liposome)-pullulan(bulk).

Carbohydrate Conformation↗

PubMed1997

Structure of the capsular polysaccharide of Clostridium perfringens Hobbs 10 determined by NMR spectroscopy.

The complete primary structure of the type-specific capsular polysaccharide of Clostridium perfringens Hobbs 10 was determined. The polysaccharide was isolated from C. perfringens Hobbs 10 by cold-water extraction of whole, heavily encapsulated cells. The polysaccharide was purified, by ethanol precipitation, deproteination, selective precipitation with hexadecyltrimethylammonium bromide, ion-exchange chromatography and gel-filtration chromatography. The polysaccharide was comprised of D-glucose, D-galactose, N-acetylgalactosamine, and iduronic acid, in molar ratios of 2:2:1:1. Sequence and linkage assignments of the glycosyl residues were obtained by NMR spectroscopy, specifically by the combination of two-dimensional homonuclear DQF-COSY, TQF-COSY and TOCSY, heteronuclear ¿1H, 13C¿ single-quantum coherence (HSQC) and heteronuclear multiple-bond correlation (HMBC) experiments. The capsular polysaccharide of C. perfringens Hobbs 10 is a polymer composed of a hexasaccharide repeating unit with the following structure: [formula: see text] This structure is novel among bacterial cell-surface polysaccharides, and it is only the second of many serotypically distinct capsular polysaccharides of C. perfringens to be described.

Bacterial Capsules↗

PubMed1969

Characterization of protein-polysaccharides of articular cartilage from mature and immature pigs.

Protein-polysaccharides of femoral articular cartilage from pigs of ages 9 months and 5 weeks were compared after extraction at pH6.8 with iso-osmotic sodium acetate followed by 0.63m-calcium acetate. The cartilage from the younger animals had a higher moisture content and contained considerably larger amounts of protein-polysaccharide, but less than half as much collagen/g. dry weight, than cartilage from the older pigs. There was notably less keratan sulphate in the fractions from the less mature animals. After gel filtration on 6% agarose, elution profiles of the calcium acetate extracts were similar to those of the sodium acetate extracts of the same tissue. Chemical analyses, however, showed that in both age-groups the extraction procedure had achieved a sequential solubilization of protein-polysaccharides in that the initial extracts contained a higher proportion of keratan sulphate than those that were extracted subsequently. Both extracts from the older animals contained up to 25% of a relatively small protein-polysaccharide that was retarded on 6% agarose and that had a lower protein content and less keratan sulphate than the larger protein-polysaccharides. In contrast, in extracts from the less mature cartilage only about 5% of the protein-polysaccharides were small enough to be retarded by 6% agarose, suggesting that the small components may not be precursors of the larger. The average length of chondroitin sulphate chains, as calculated from the analytical data, was the same in the smaller protein-polysaccharides as in the larger.

Animals↗

PubMed1971

Heterogeneity of protein-polysaccharides of porcine articular cartilage. The chondroitin sulphate proteins associaterd with collagen.

Pig articular cartilage, from which protein-polysaccharides soluble in iso-osmotic sodium acetate had been removed, was extracted in three further stages with 8m-urea in 2m-sodium acetate and with tris-HCl buffer after bacterial collagenase digestion, followed by the same urea-sodium acetate solution, thus leaving only 2% of the original uronic acid in the tissue. The histological appearance of the cartilage was unaltered until after collagenase digestion. The collagenase used did not affect the viscosity or molecular size of a protein-polysaccharide preparation obtained previously. The protein-polysaccharides in each extract differed in size, amino acid composition and protein content, but protein and keratan sulphate contents were not related to hydrodynamic size, in contrast with protein-polysaccharides extracted previously before collagenase digestion. Hydroxyproline could not be removed from those obtained by the first urea-sodium acetate extraction until degraded by heat. The galactosamine/pentose molar ratio agreed closely with the galactosamine/serine molar ratio that was destroyed on treatment with 0.5m-sodium hydroxide, showing that chondroitin sulphate was attached only to serine residues. From these molar ratios the chondroitin sulphate chains were calculated to be of the same average length in protein-polysaccharides in all three extracts although somewhat shorter than in protein-polysaccharides extracted previously. Some threonine residues were also destroyed on alkali treatment suggesting that keratan sulphate may be attached to threonine. These findings together with previous results show that differences in size, composition and physical state extend to all the protein-polysaccharides in cartilage.

Acetates↗

PubMed2002

Structural studies on the core and the O-polysaccharide repeating unit of Pseudomonas aeruginosa immunotype 1 lipopolysaccharide.

The structure of the lipopolysaccharide (LPS) of Pseudomonas aeruginosa immunotype 1 was studied after mild acid and strong alkaline degradations by MS and NMR spectroscopy. Three types of LPS molecules were found, including those with an unsubstituted glycoform 1 core (A) or an isomeric glycoform 2 core substituted with one O-polysaccharide repeating unit (B) or with a long-chain O-polysaccharide. Therefore, of two core glycoforms, only glycoform 2 accepts the O-polysaccharide. In the structures A and B, Kdo, Hep, Hep7Cm, GalNAcAN3Ac, GalNFoAN, QuiNAc, GalNAla represent 3-deoxy-d-manno-octulosonic acid, l-glycero-d-manno-heptose, 7-O-carbamoyl-l-glycero-d-manno-heptose, 2-acetamido-3-O-acetyl-2-deoxygalacturonamide, 2-formamido-2-deoxygalacturonamide, 2-acetamido-2,6-dideoxyglucose and 2-(l-alanylamino)-2-deoxygalactose, respectively; all sugars are in the pyranose form and have the d configuration unless otherwise stated. One or more phosphorylation sites may be occupied by diphosphate groups. In a minority of the LPS molecules, an O-acetyl group is present in the outer core region at unknown position. The site and the configuration of the linkage between the O-polysaccharide and the core and the structure of the O-polysaccharide repeating unit were defined in P. aeruginosa immunotype 1. The QuiNAc residue linked to the Rha residue of the core was found to have the beta configuration, whereas in the interior repeating units of the O-polysaccharide this residue is in the alpha-configuration. The data obtained are in accordance with the initiation of biosynthesis of the O-polysaccharide of P. aeruginosa O6, which is closely related to immunotype 1, by transfer of d-QuiNAc-1-P to undecaprenyl phosphate followed by synthesis of the repeating O-antigen tetrasaccharide.

Carbohydrate Sequence↗

PubMed1989

Prevention of pneumococcal bacteremia by immunization with type 6 pneumococcal capsular polysaccharide vaccine in splenectomized rats.

Postsplenectomy sepsis is well recognized and prophylactic vaccination with pneumococcal polysaccharide is recommended. However, the efficacy of vaccination with the polysaccharide in splenectomized individuals is not clear. The effect of type 6 pneumococcal polysaccharide vaccine on the clearance of pneumococci from the bloodstream and lung was studied in splenectomized rats as was survival after intravenous challenge with Streptococcus pneumoniae, serum opsonic activity, and specific antibody titer by ELISA. Rats immunized with type 6 pneumococcal polysaccharide vaccine had significantly increased survival (P less than .05) and clearance of pneumococci from the bloodstream and lung (P less than .05) after intravenous challenge with S. pneumoniae, significantly higher serum opsonic activity (P less than .02), and increased specific IgG and IgM antibody titer to the type 6 polysaccharide compared with controls treated with saline. There was close correlation between IgG antibody titer to type 6 polysaccharide and opsonic activity (r = .95). These results suggest that pneumococcal polysaccharide vaccine is effective for preventing pneumococcal bacteremia in splenectomized hosts.

Animals↗

PubMed1996

Cell-Wall Polysaccharides of Developing Flax Plants.

Flax (Linum usitatissimum L.) fibers originate from procambial cells of the protophloem and develop in cortical bundles that encircle the vascular cylinder. We determined the polysaccharide composition of the cell walls from various organs of the developing flax plant, from fiber-rich strips peeled from the stem, and from the xylem. Ammonium oxalate-soluble polysaccharides from all tissues contained 5-linked arabinans with low degrees of branching, rhamnogalacturonans, and polygalacturonic acid. The fiber-rich peels contained, in addition, substantial amounts of a buffer-soluble, 4-linked galactan branched at the 0-2 and 0-3 positions with nonreducing terminal-galactosyl units. The cross-linking glycans from all tissues were (fucogalacto)xyloglucan, typical of type-I cell walls, xylans containing (1->)-[beta]-D-xylosyl units branched exclusively at the xylosyl O-2 with t-(4-O-methyl)-glucosyluronic acid units, and (galacto)glucomannans. Tissues containing predominantly primary cell wall contained a larger proportion of xyloglucan. The xylem cells were composed of about 60% 4-xylans, 32% cellulose, and small amounts of pectin and the other cross-linking polysaccharides. The noncellulosic polysaccharides of flax exhibit an uncommonly low degree of branching compared to similar polysaccharides from other flowering plants. Although the relative abundance of the various noncellulosic polysaccharides varies widely among the different cell types, the linkage structure and degree of branching of several of the noncellulosic polysaccharides are invariant.

Journal Article↗

PubMed1967

Formation of a soluble amylopectin-like polysaccharide in potato tubers.

When potato sprouts or potato tuber slices were incubated with 0.1 m glucose 1-phosphate, a soluble amylopectin-like polysaccharide was excreted to the medium. This polysaccharide was found to be a very good primer for phosphorylase and a poor one for starch synthetase. Beside the formation of this extracellular polysaccharide, a more branched intracellular polysaccharide could be isolated. This polysaccharide was an excellent primer for starch synthetase. Fructose 6-phosphate, glucose 6-phosphate, fructose 1,6-diphosphate, glucose or sucrose could not substitute for glucose 1-phosphate. 2,4-Dinitrophenol or nitrogen did not affect the excretion of the polysaccharide. Some properties of these 2 polysaccharides are described.

Journal Article↗

PubMed1984

Pectic polysaccharide breakdown of cell walls in cucumber roots grown with calcium starvation.

Pectic polysaccharides from the roots of cucumber (Cucumis sativus L.) grown in liquid culture medium with or without calcium (1 mm CaCl(2)) were studied after extraction successively by hot water and Na hexametaphosphate solution. The Ca(2+) starvation-treatment caused a striking reduction in content of extracted pectic polysaccharide; from an equivalent weight of cell walls, only 33.1% of the control level was extracted from root cell walls of plants cultured under Ca(2+) deficiency. The extracted pectic polysaccharides were fractionated into neutral and acidic polymers by a DEAE-Sephadex column. The acidic polymers, which represented more than 76% of the yield, appeared to be a major fraction of extracted pectic polysaccharides. The changes of molecular size and glycosyl residue composition of this fraction were compared for the control and Ca(2+)-deprived samples. The results indicate that Ca(2+) deficiency caused structural changes which could involve both branching pattern and extent of contiguous galacturonosyl units in the water-solubilized pectic polysaccharides. Ca(2+) starvation also led to a notable decrease in molecular size of the hexametaphosphate-solubilized polysaccharides and, to a lesser extent, of the water-solubilized fraction as well. In addition, polygalacturonase activity in tissue homogenates increased remarkably with the Ca(2+) deficiency, whereas beta-galactosidase activity did not undergo a change. Thus, it appears that one major effect of Ca(2+) deprivation was to stimulate polygalacturonase activity, an effect which could be involved in the control of the breakdown of pectic polysaccharides in the cell walls.

Journal Article↗

PubMed1996

Structure of the O-specific polysaccharide of an Aeromonas trota strain cross-reactive with Vibrio cholerae O139 Bengal.

The O-specific polysaccharide of an Aeromonas trota strain was isolated by hydrolysis of the lipopolysaccharide at pH 4.5 followed by gel-permeation chromatography and found to consist of hexasaccharide repeating units containing D-galactose, L-rhamnose, 3,6-dideoxy-L-xylo-hexose (colitose, Col), 2-acetamido-2-deoxy-D-glucose and 2-acetamido-2-deoxy-D-galactose in the ratios 1:1:2:1:1. Partial hydrolysis of the polysaccharide with 48% hydrofluoric acid resulted in selective removal of colitose to give a modified polysaccharide containing the other four sugar constituents. On the basis of methylation analysis and NMR spectroscopic studies of the initial and modified, colitose-free polysaccharide, it was concluded that the repeating unit of the O-specific polysaccharide has the following structure [sequence: see text] The known cross-reactivity between the strain studied and Vibrio cholerae O139 Bengal is substantiated by the presence of a common colitose-containing epitope shared by the O-specific polysaccharide of A. trota and the capsular polysaccharide of V. cholerae, which is thought to carry determinants of O-specificity.

Aeromonas↗

PubMed1998

Monoclonal antibodies with specificities for Streptococcus pneumoniae group 9 capsular polysaccharides.

Streptococcus pneumoniae group 9 includes four capsular polysaccharide types: 9A, 9L, 9N and 9V. We have generated four mouse monoclonal antibodies against group 9 polysaccharide using heat-treated S. pneumoniae strains of different capsular polysaccharides types as immunogens. The specificities of the monoclonal antibodies were determined by ELISA using capsular polysaccharide directly coated to the wells as antigens and by dot blotting with heat-treated bacteria. Two groups of monoclonal antibodies were found. The first group included two monoclonal antibodies which were found to be capsular type specific. The second group was monoclonal antibodies that bound to epitopes shared by two or three pneumococcal group 9 types. The monoclonal antibody 204,A-4 (IgM) was found to be specific for S. pneumoniae type 9N. The binding of the type 9V specific monoclonal antibody 206,F-5 (IgG1) was found to be dependent upon O-acetyl groups. Monoclonal antibody 205,F-3 (IgM) reacted also with type 9V, but was found to cross-react with types 9A and 9L. The binding of this monoclonal antibody to polysaccharide 9V was not dependent upon O-acetyl moieties. The fourth monoclonal antibody (214,G-5, isotype IgM) did not show any correlation between reactivity with isolated polysaccharides and dot blotting with relevant bacteria. The monoclonal antibody reacted with polysaccharides 9A and 9L in ELISA, but not with the homologous bacteria.

Age Factors↗

PubMed1993

Synthesis of the K5 (group II) capsular polysaccharide in transport-deficient recombinant Escherichia coli.

The genes directing the expression of group II capsules in Escherichia coli are organized into three regions. The central region 2 is type specific and thought to determine the synthesis of the respective polysaccharide, whilst the flanking regions 1 and 3 are common to all group II gene clusters and direct the surface expression of the capsular polysaccharide. In this communication we analyze the involvement of region 1 and 3 genes in the synthesis of the capsular KS polysaccharide. Recombinant E. coli strains harboring all KS specific region 2 genes and having various combinations of region 1 and 3 genes were studied using immunoelectron microscopy. Membranes from these bacteria were incubated with UDP[14C]GlcA and UDPGlcNAc in the absence or presence of KS polysaccharide as an exogenous acceptor. It was found that recombinant strains with only gene region 2 did not produce the K5 polysaccharide. Membranes of such strains did not synthesize the polymer and did not elongate K5 polysaccharide added as an exogenous acceptor. An involvement of genes from region 1 (notably kpsC and kpsS) and from region 3 (notably kpsT) in the K5 polysaccharide synthesis was apparent and is discussed.

Antigens, Bacterial↗

PubMed1999

Determination of antibody responses of elderly adults to all 23 capsular polysaccharides after pneumococcal vaccination.

The 23-valent pneumococcal polysaccharide vaccine was formulated to prevent invasive infection in the elderly and other high-risk populations from the most prevalent Streptococcus pneumoniae serotypes. However, the immunogenicity of all 23 vaccine polysaccharides has not been fully characterized in elderly adults. We previously reported that whereas the majority of elderly subjects had vigorous immune responses to selected pneumococcal vaccine polysaccharides, a subset of elderly individuals responded to fewer than two of seven vaccine serotypes after immunization. To determine whether these elderly low responders have a general inability to respond to pneumococcal vaccine and to determine whether elderly low responders might be identified by their responses to a few polysaccharides, we measured antibody responses of elderly adults to all 23 vaccine polysaccharides after pneumococcal immunization. As a group, elderly subjects showed a significant rise after immunization in geometric mean antibody levels to all 23 vaccine serotypes. However, when individual rather than group immune responses were assessed, the 23-valent vaccine did not appear to be uniformly immunogenic in these elderly subjects. Eleven elderly subjects (20%) had twofold increases in specific antibody after vaccination to only 5 or fewer of the 23 vaccine polysaccharides, and they did not respond to the most prevalent serotypes causing invasive disease. Antibody responses to serotype 9N were found to reliably distinguish low vaccine responders from other elderly subjects. However, no particular group of vaccine polysaccharides could be used as a marker for adequate immune responses if only postvaccination sera were analyzed.

Aged↗

PubMed1999

Analysis of a capsular polysaccharide biosynthesis locus of Bacteroides fragilis.

A major clinical manifestation of infection with Bacteroides fragilis is the formation of intra-abdominal abscesses, which are induced by the capsular polysaccharides of this organism. Transposon mutagenesis was used to locate genes involved in the synthesis of capsular polysaccharides. A 24,454-bp region was sequenced and found to contain a 15,379-bp locus (designated wcf) with 16 open reading frames (ORFs) encoding products similar to those encoded by genes of other bacterial polysaccharide biosynthesis loci. Four genes encode products that are similar to enzymes involved in nucleotide sugar biosynthesis. Seven genes encode products that are similar to sugar transferases. Two gene products are similar to O-acetyltransferases, and two products are probably involved in polysaccharide transport and polymerization. The product of one ORF, WcfH, is similar to a set of deacetylases of the NodB family. Deletion mutants demonstrated that the wcf locus is necessary for the synthesis of polysaccharide B, one of the two capsular polysaccharides of B. fragilis 9343. The virulence of the polysaccharide B-deficient mutant was comparable to that of the wild type in terms of its ability to induce abscesses in a rat model of intra-abdominal infection.

Animals↗

PubMed2000

Capsular polysaccharide and O-specific antigen divergently modulate pulmonary neutrophil influx in an Escherichia coli model of gram-negative pneumonitis in rats.

Enteric gram-negative bacilli cause a severe, often life-threatening pneumonia. An improved understanding of the pathogenesis of this infection may lead to improved treatment. Nearly all of the responsible gram-negative bacilli possess capsular polysaccharides and/or an O-specific antigen as part of their lipopolysaccharide (LPS). We hypothesized that these surface polysaccharides may modulate the pulmonary host response. To investigate this, a rat pneumonitis model was used, and pulmonary neutrophil influx, a critical aspect of host defense, was measured. To assess for the effect of the capsule and O-specific antigen on this host response, three proven, isogenic derivatives that are deficient in capsular polysaccharide alone (CP9.137), the O-specific antigen moiety of the LPS alone (CP921), and both the capsular polysaccharide and O-specific antigen (CP923), as well as their wild-type parent (CP9), were used as challenge strains at various intratracheal challenge inocula (CI). Total lung myeloperoxidase (MPO), a surrogate marker for neutrophils, was measured for 15 h post-bacterial challenge. To determine the effect of capsule and the O-specific antigen on the measured MPO levels, a mathematical model was developed and used to describe the MPO levels as a function of time for each CI of each of the four strains. The results from this analysis demonstrated that in the absence of the K54 capsule, 80.7 times the CI is necessary to achieve the same maximum MPO level relative to K54 positive strains (P < 0.0001). In contrast, a diametric effect was observed in the absence of the O-specific antigen, where 0.13 times the CI was necessary to achieve the same maximum MPO level relative to O4-positive strains (P = 0.0032). No interactive effect was observed between the capsule and the O-specific antigen. These findings demonstrate that these surface polysaccharides modulate pulmonary neutrophil influx and suggest that the K54 capsular polysaccharide is a proinflammatory mediator and that the O4-specific antigen attenuates the proinflammatory response. If these speculations are substantiated, an understanding of how the capsule and the O-specific antigen modulate host response could have significant therapeutic implications. The potential use of biologic modulators directed against the host response, as well as approaches based on inactivating bacterial components (e.g., surface polysaccharides) in attempts to modify sepsis syndromes, could be developed.

Animals↗

PubMed2006

Mesorhizobium loti produces nodPQ-dependent sulfated cell surface polysaccharides.

Leguminous plants and bacteria from the family Rhizobiaceae form a symbiotic relationship, which culminates in novel plant structures called root nodules. The indeterminate symbiosis that forms between Sinorhizobium meliloti and alfalfa requires biosynthesis of Nod factor, a beta-1,4-linked lipochitooligosaccharide that contains an essential 6-O-sulfate modification. S. meliloti also produces sulfated cell surface polysaccharides, such as lipopolysaccharide (LPS). The physiological function of sulfated cell surface polysaccharides is unclear, although mutants of S. meliloti with reduced LPS sulfation exhibit symbiotic abnormalities. Using a bioinformatic approach, we identified a homolog of the S. meliloti carbohydrate sulfotransferase, LpsS, in Mesorhizobium loti. M. loti participates in a determinate symbiosis with the legume Lotus japonicus. We showed that M. loti produces sulfated forms of LPS and capsular polysaccharide (KPS). To investigate the physiological function of sulfated polysaccharides in M. loti, we identified and disabled an M. loti homolog of the sulfate-activating genes, nodPQ, which resulted in undetectable amounts of sulfated cell surface polysaccharides and a cysteine auxotrophy. We concomitantly disabled an M. loti cysH homolog, which disrupted cysteine biosynthesis without reducing cell surface polysaccharide sulfation. Our experiments demonstrated that the nodPQ mutant, but not the cysH mutant, showed an altered KPS structure and a diminished ability to elicit nodules on its host legume, Lotus japonicus. Interestingly, the nodPQ mutant also exhibited a more rapid growth rate and appeared to outcompete wild-type M. loti for nodule colonization. These results suggest that sulfated cell surface polysaccharides are required for optimum nodule formation but limit growth rate and nodule colonization in M. loti.

Alphaproteobacteria↗