Facile in vivo transfer of mutations between the Bacillus subtilis chromosome and a plasmid harbouring homologous DNA.

Transformation of Bacillus subtilis strains carrying the point mutations spoIIA42 or spoIIA69 by a plasmid, pHM2, carrying the spoIIA+ allele gave occasional recombinants in which the plasmid had acquired the chromosomal mutation. Transformation of a spo+ strain by these derivative plasmids gave occasional recombinants in which the chromosome of the recipient had acquired the plasmid-borne spoIIA mutation. Both types of behaviour were recE+-dependent. Mutations spoIIA42 and spoIIA69 fell into a single complementation group.