Deletions of mob and tra pJP4 transfer functions after mating of Ralstoniaeutropha JMP134 (pJP4) with Escherichia coli harboring F '::Tn10

One-tenth of Escherichia coli transconjugants resulting from the transfer o f the catabolic plasmid pJP4 from Ralstonia eutropha JMP134 to E. coli XL1B lue, contained pJP4 derivatives with deletions (similar to 15-30 kb). The o ccurrence of these deletions is probably associated with the presence of Tn 10 in the recipient. DNA endonuclease restriction analysis of the pJP4 dele tion derivatives showed the absence of SphI and EcoRI fragments previously reported to hybridize with IncP Tra DNA probes. Moreover, these pJP4 deleti on derivatives are not able to self-transfer, nor are they able to be mobil ized. Accordingly, these pJP4 deletion derivatives lack transfer functions.