Metabolic properties, stress tolerance and macromolecular profiles of rhizobia nodulating Hedysarum coronarium
1998
Struffi, | Corich, | Giacomini, | Benguedouar, | Squartini, | Casella, | Nuti,
The droughtâtolerant legume Hedysarum coronarium is a Mediterranean species valued as a forage crop for its high performance in stressful conditions. The plant shows peculiar capabilities of nodulating above pH 9 and thriving in highly calcareous soils. With the aim of providing an adequate characterization of its bacterial symbiotic partner, a study was undertaken, approaching from several viewpoints the physiology and structural features of bacteria isolated from nodules of H. coronarium. Tests involved trophic capabilities on different carbon and nitrogen sources, vitamin requirements, and resistance to factors including antibiotics, heavy metals, salinity, pH, and temperature. Enzyme activities, including those of cellulase, pectinase, urease, βâgalactosidase, nitrate and nitrite reductase, were evaluated. The DNA G + C percentage content was determined. Speciesâspecific bacteriophages were isolated and a strainâtyping grid established. In order to characterize further and fingerprint the different Rhizobium ‘hedysari’ isolates, electrophoretic pattern of proteins, plasmid DNA, and digested genomic DNA (in pulsedâfield gel separation) were compared. Adansonian taxonomy yielded similarity clusters of the different isolates.
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