Figure 6.

Genetic strategy to conditionally overexpress XylR in P. putida upon IPTG addition. (a) Organization of the mini-Tn7 carrying xylR under control of lacI^q/Ptrc system and assembled in vector pTn7-M to yield the mini-Tn7 [L-Gm lacI^q/Ptrc → xylR-R] transposon delivery plasmid pIB. (b) The business part of the mini tranposon is then inserted into the attTn7 site (close to the glmS gene) of recipient strain P. putida KT [Pu-GFP], which bears a chromosomally determined transcriptional Pu-GFP fusion (see Materials and methods). In the resulting strain (P. putida KT-IB1), XylR production depends on the concentration of IPTG added to the medium, while m-xylene is added to activate XylR for triggering Pu promoter activity.