Genetic evidence for possible interaction between a ribonucleic acid polymerase subunit and the spo0C gene product of...

Spontaneous rifampin-resistant mutants (9V Rifr) were isolated from a mutant strain of Bacillus subtilis, 9V, which has a spo0C mutation. Whereas 90% of the 9V Rifr double mutants maintained the Spo0C phenotype (Spo- Abs +/-), the remaining 10% had the Spo0A phenotype (Spo- Abs-). The latter mutants, termed 9V Rifr Spo- Abs-, were revealed to have other Spo0A characters, such as reduced transformability, higher sensitivity to phage phi 2, and reduced frequency of lysogenization by phage phi 105. The rif mutation of these 9V Rifr Spo- Abs- strains was mapped near the cysA locus. The phenotype of the Rifr transformants of strain 9V by deoxyribonucleic acid derived from these 9V Rifr Spo- Abs- strains was Spo0A, and that of the Rifr transformants of strain 168 was Spo+ Abs+. The ribonucleic acid polymerase of the 9V Rifr Spo- Abs- strains was shown to be resistant to rifampin.