[Inheritance of hybrid plasmid pAS*-21 by cells of the purple phototropic nitrogen-fixing bacterium Rhodopseudomonas sphaeroides].

Clones of purple nitrogenfixing prototrophic bacterium Rhodopseudomonas sphaeroides carrying an incertion into the chromosome of the hybrid pAS8-121 (RP4-ColE1 (repA::Tn7] plasmid were analysed. It is revealed that plasmid integration could be due to both Tn7 and other migrating elements (IS8 and possibly, to resident migrating elements of purple bacteria). The plasmid pAS 8-121 can be autonomously transferred from the cointegrate state into Escherichia coli K-12; the plasmid is not inherited autonomously in cells of the purple bacterium. In E. coli cells R' derivatives of the plasmid carrying R. sphaeroides chromosomal fragments may be formed. The R' plasmids with fragments of plasmid DNA substituted for chromosomal material of R. sphaeroides were selected in E. coli K-12 cells among deleted (Kms) derivatives of pAS8-121.