Investigation of a phage resistant Serratia entomophila strain (BC4B), establishment of generalised transduction and construction of S. entomophila RecA mutants.

A recA clone was isolated from a cosmid library of Serratia entomophila constructed in the Escherichia coli strain HB101. Subcloning and transposon mutagenesis were used to identify a 1.36 kb fragment containing the recA gene. A cloned recA mutation, generated by transposon mutagenesis and the replacement of a portion of the recA gene with an antibiotic resistance cassette, was introduced into the chromosome via a marker exchange technique. The recA strains created were deficient in DNA repair, homologous recombination and both the spontaneous and UV induction of prophages. S. entomophila recA strains showed continued pathogenicity towards the New Zealand grass grub, Costelytra zealandica. Simple procedures for further construction of S. entomophila recA strains have been demonstrated.