[Lethal and mutagenic action of UV light on salmonellae carrying wild or mutant alleles of the Escherichia coli lexA-gene].

To elucidate the reasons for the absence of UV-mutability in Salmonella typhimurium, the lexA gene of Escherichia coli has been transduced by phage P1 into S. typhimurium. The functioning of lexA+ allele of E. coli in the chromosome of Salmonella failed to cause UV-mutability of the hybrid. The transfer of pKM101 plasmid into the LexA+ hybrid mediates the expressed UV mutability and UV-protective plasmid effect. This plasmid harboured by the LexA hybrid fails to increase UV-resistance and mutability, thus showing the dependence of plasmid mediated effect on LexA+ phenotype.