Degree Name

Master of Science (MS)

Semester of Degree Completion

1988

Thesis Director

Russell Carlson

Abstract

The lipopolysaccharides (LPSs) of the Rhizobium phaseoli CE3 and its mutants CE109, CE309 and the transconjugate Rhizobium leguminosarum LB2/109.11 were isolated and analyzed by gas chromatography (GC) and 1H nuclear magnetic resonance (NMR) spectroscopy. CE3 is the wild type strain which is nodulation-proficient (Nod+). Strain CE109 and CE309 have a transposon, Tn5, inserted into Region I and Region III of their respetive chromosomes. Mutants CE109 and CE309 are defective in nodule development (Ndv-). Transconjugate R. leg. LB2/109.11 has the DNA of the R. leg. LB2 wild type and also Region I portion of the CE109 where the Tn5 is inserted. This mutant is Nod+on peas.

Mild acid hydrolysis of the LPSs gives a precipitate (lipid A) and supernatant (O-antigen and core polysaccharides). In the separation of the supernatant components by Bio-Gel P2 column, three peaks are detected, LPS-P2-1, LPS-P2-2 and LPS-P2-3. The first peak corresponds to the O-antigen and the others two are the components of the core. The GC analysis of the LPSs shows that the mutant CE109 and CE309 lack the O-antigen; in contrast, LB2/109.11 has sugars corresponding to the O-antigens from both parent strains, CE3 and LB2. Both LPS-P2-2 and LPS-P2-3 are altered in GalA content for CE109 and only LPS-P2-2 is altered, lacking Gal and GalA, for CE309. These core components from LB2/109.11 are the same as those from CE3.

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