[Introduction of the bacteriophage Mu into a nitrogen-fixing strain Klebsiella pneumoniae M 5 a 1].

Mu cts 62 a thermo-inductible mutant of phage Mu was integrated in E. coli in to the broad host range RP4 plasmid. The hybrid plasmid RP4::Mu cts 62 was then transferred by mating to the dinitrogen-fixing strain K. pneumoniae M5al. In Klebsiella Mu cts 62 is still heat inducible and the phage production is similar to that observed in E. coli. Mu Should be a useful tool for the genetic analysis of nitrogen fixation.