The temperature sensitive mutant 72c. I. Pleiotropic growth behaviour and changed response to some antibiotics and mutations in the transcription or translation apparatus.

The spontaneous temperature sensitive mutant 72c is shown to be more tolerant to fusidic acid, but less tolerant to trimethoprim on plates at permissive temperature, than is the parental strain. The poor growth of the mutant on amino acids supplemented plates, as well as its inability to grow on broth plates at 40 degrees, can be compensates by sublethal amounts of chloroamphenicol. Also some mutations to Rif-R or Str-R improve growth of the mutant under certain conditions. Reversion and other genetic analysis strongly suggest, that the pleiotropic behaviour of the mutant is due to a single mutation in a gene, which is designated fusB and is closely cotransducible with lip at min 14 of the E. coli chromosome. The gene order is lip-fusB-supE.