Hybridization to pCW3-derived probes. Total DNA isolated from strains JIR325 and JIR4468 was digested with BamHI, Southern blotted, and probed separately with the five pCW3-derived ClaI fragments that are present in the recombinant plasmids (1) pJIR15 (A), pJIR17 (B), pJIR16 (C), pJIR18 (D), and pJIR32 (E), as indicated. The pCW3 circular map shows the location of the five ClaI fragments (A through E).