RESUMO
Two recent reports described the isolation of derivatives of a Rhizobium trifolii strain that had gained the ability to nodulate Glycine max and Vigna radiata and that had demonstrated altered patterns of carbon source utilization, free-living nitrogen fixation, and hydrogen uptake. More extensive characterization of these strains now supports the conclusion that these strains are R. japonicum and are not derived from the putative parent R. trifolii.
RESUMO
Bacteriocins produced by six strains of Rhizobium trifolii were found to be of the relatively low molecular weight, non-phage type. The molecular weights ranged from approximately 1-8 X 105 to 2-0 X 105. All were of protein composition, as indicated by buoyant density (1-32 to 1-34 g/cm3) in CsC1 and by sensitivity to proteolytic enzymes. They were resistant to RNAase but sensitive to DNAase. The six bacteriocins could further be separated into two subgroups on the basis of sensitivity to extremes of pH, binding to filter membranes, activity spectrum on sensitive strains of R. trifolii, and possibly mode of action on sensitive bacteria. Bacteriocin production occurred spontaneously during the early-to mid-exponential phase of bacterial growth in broth culture.
