Lytic activity associated with the prophage 01 of P. fluorescens Pf-5. Putative holin (PFL_1211) (A) and endolysin (PFL_1227) (B) genes encoded by prophage 01 from P. fluorescens Pf-5 were cloned in the plasmid vector pCR-Blunt (Invitrogen) under the control of the IPTG-inducible T7 promoter. Broth cultures of E. coli Rosetta/pLysS bearing the cloned holin and endolysin genes were induced with 3 mM IPTG and incubated with shaking for 5 hours while monitoring cell growth by measuring OD600. The arrow indicates the time of addition of chloroform to the endolysin-expressing culture. Two independent repetitions of the assay were carried out for each gene and yielded identical results (data not shown).