The Somatic Antigens of Two Strains of Rhizobium trifolii

Abstract

SUMMARYStrain-specific lipopolysaccharide extracted by hot phenol from two strains of Rhizobium trifolii was fully antigenic in rabbits with an injection schedule using Freund's adjuvant, and highly active in gel diffusion. A minor second diffusion line was considered to be due to a smaller fragment of the main molecule, since the antigen was converted almost entirely to this form by sodium dodecylsulphate and such disaggregated material absorbed antibodies to both forms of the antigen. Chemically the lipopolysaccharide showed some features related to those of the Enterobacteriaceae; for example, the presence of firmly bound lipid, 2-keto-3-deoxyoctonate, glucose, mannose, fucose and, in one strain, a heptose. However, the lipopolysaccharide of R. trifolii was unusual in its very low phosphorus content and the presence of glucuronic acid. One strain diverged even further in its high content of carbohydrate, its lack of a heptose, its anionic behaviour and the gelatinous nature of some preparations ; these properties might relate to the presence of a capsule-like structure which has been observed in old cultures of this strain.

Lysogenic Conversion of Rhizobium trifolii

“…The parallel loss of phage-adsorbing capacity and the change in surface antigen found with lysogenized s u q 7 suggests that the receptor site for phages 7,7cr and 8 is associated with the lipopolysaccharide somatic antigen of these bacteria (Humphrey &Vincent, 1969). Receptor sites for several T phages and ShigeIla phages have been found in the lipopolysaccharide surface layer (Jesaitis & Goebel, 1955 ;Beumer, Beumer-Jochans, Dirkx & Dekeil, 1966) and some earlier work with rhizobial phages showed a relationship between antigenic constitution and susceptibility to specific phages (Marshall & Vincent, 1954).…”

“…The bacteria were then sedimented and the residual somatic agglutination titre of the supernatant determined with the strain of bacterium that had been used for developing the antiserum under test. Gel diffusion followed the detailed procedure of Humphrey & Vincent (1969 …”

Composition of Lipopolysaccharides from Pseudomonas syringae pv. syringae and a Serological Comparison with Lipopolysaccharide from P. syringae pv. morsprunorum

“…The pattern of substitution must be such as not to interfere with the action of rhamnanase which cleaves the glycosidic bond 2)-~-Rhap(a1+3) (Smith et al, 1984). Fucose is also a constituent of LPS from P. syringae pathovars (Anderson, 1984), and is a common component of LPS from other phytopathogens including species of Xanthomonas (Volk, 1968), Rhizobium (Humphrey & Vincent, 1969;Carlson et al, 1978; Hrabak et a/., 1981) and Agrobacterium (Manasse & Corpe, 1967). To evaluate the significance of fucose as a taxonomic marker for distinguishing isolates of P .…”

The Lipopolysaccharide of Free-living and Bacteroid Forms of Rhizobium leguminosarum

“…However, all Rhizobium wall polysaccharide preparations contain at least fucose, rnannose and KDO (Humphrey & Vincent, 1969 (1978) and this paper for differences between strains of R. Zeguminosarum]. The composition of the LPS from the related genus Agrobacterium is also largely unknown.…”

“…Thus a thorough study and characterization of the lipopolysaccharide (LPS) and other surface polysaccharides of Rhizobium was desirable. Only partial analyses of LPS of Rhizobium have beem reported previously (Humphrey & Vincent, 1969;Graham & O'Brien, 1968;Russa & Lorkiewicz, 1974;Oparin, 1976). This paper describes the chemical composition of LPS of bacteria and bacteroids of Rhizobium leguminosarum strain ~1 7 1 .…”