Standard recombinant DNA procedures were performed as described by Sambrook and Russell (29 ). DNA fragments were extracted from agarose gels using the QIAquick gel extraction kit and from liquids using the QIAquick PCR purification kit (QIAGEN). Plasmid DNA was isolated using the Wizard Plus SV Minipreps DNA purification kit (Promega) or the NucleoBond Xtra Midi kit (Macherey-Nagel). Synthetic oligonucleotides were ordered from Sigma-Aldrich or Eurofins. Restriction cloning was performed according to recommendations from New England Biolabs. PCR reactions were carried out with the Expand High Fidelity PCR System (Roche Applied Science) or Q5 High-Fidelity DNA Polymerase (NEB). Escherichia coli clones were transformed using a modified RbCl protocol (Promega) and P. putida KT2440 was transformed using an electroporation protocol described by Hanahan et al. (30 (link)). The constructed plasmids were confirmed by sequencing performed at Eurofins/GATC Biotech using primer 5′-AACGGCCTGCTCCATGACAA-3′ for pAO-Tr-, pIB11- (18 (link)), pdualUTR-; and primers 5′-CTTTCACCAGCGTTTCTGGGTG-3′ and 5′-CAAGGATCTTACCGCTGTTG-3′ for pAO-Tn-based constructs.