TRANSPOSON TN5 MUTAGENESIS OF PSEUDOMONAS-FLUORESCENS TO ISOLATE MUTANTS DEFICIENT IN ANTIBACTERIAL ACTIVITY

Pseudomonas fluorescens was subjected to insertion mutagenesis studies using the transposon Tn5-GM to generate mutants deficient in antibact erial activity minus mutants. The transposon located on the temperatur e-sensitive plasmid pCHR84 was conjugally transferred into the non-pat hogenic pseudomonad using the triparental mating procedure. Random int egration of Tn5-GM into the chromosome of P. fluorescens was achieved by heat treatment of the transformed cells at 42 degrees C. Approximat ely 2% of transconjugants revealed an auxotrophic phenotype indicating efficient integration of the employed transposon into the chromosome of P. fluorescens. One transposon insertion mutant was obtained showin g an antibacterial activity minus phenotype. This mutant (MM-7) was fo und to be defective in the production of an unidentified antibacterial compound against B. subtilis. These results introduce Tn5 transposon mutagenesis as a new useful tool for the molecular analysis of P. fluo rescens.