Rhizobium meliloti Tn5 induced auxotrophic mutants responding to different biosynthetic intermediates

Abstract

Using a suicide plasmid as a vector, the kanamycin–neomycin resistance conferring transposon Tn5 was introduced into the genome of the two Rhizobium meliloti strains 444 and M28str. Among clones carrying random Tn5 insertions, about 0.3% auxotrophic mutants were isolated from each strain. Tn5 was found to integrate preferentially into genes involved in syntheses of adenine, arginine, leucine, pyrimidines, sulphur-containing amino acids, and tryptophan. Growth responses to biosynthetic intermediates uncovered four and two groups of methionine- and tryptophan-requiring mutants, respectively.