FIG. 4.

Southern blot of total chromosomal DNA extracted from various toxigenic and nontoxigenic E. coli, digested with EcoRI and hybridized with either a 4.9-kb (A) or a 5.5-kb (B) probe from the toxin-converting phage isolated from E. coli 86-24. Lanes 1, EHEC strain 86-24; lanes 2, E. coli TUV82-2; lanes 3, phage-cured isolate of EHEC strain 86-24; lanes 4, E. coli 87-23 (no SLT), lanes 5, E. coli C600; lanes 6, phage λ; lanes 7, the SLT-II-converting phage from EHEC strain 86-24. Fragment sizes were estimated by using a 1-kb DNA ladder.