1. B2 1. The mutagenized bphABC DNA car- However the KF707 enzyme system is
2. ried by a suicide plasmid was then intro- almost inactive to benzene and its deriva
3. duced back into the parent strain KF707 tives. Another Pseudomonas sp. KF712
4. resulting in the appearance of mutants in produced Bph enzymes that showed much
5. which Tn 5-B21 was gene-specifically wider substrate ranges compared with the