Published online by Cambridge University Press: 14 April 2009
An amber mutation was created in the CAT gene of plasmid vector pACYC184 and this modified plasmid was fused with the Streptomyces vector pIJ702 for use as an indicator for the identification of Streptomyces strains carrying nonsense suppressor tRNA mutations. The resulting hybrid plasmid pGM1109 was introduced into the chloramphenicol-sensitive mutant M252 of Streptomyces lividans. Chloramphenicol-resistant colonies were isolated and characterized. None of them was a nonsense suppressor mutant. The failure to obtain such mutants is discussed on the basis of codon usage in streptomycetes.