. 2020 Oct 20;11:5294. doi: 10.1038/s41467-020-19124-x

Table 2.

Overview and comparison of relevant induction systems often used in P. putida.

TF	Promoter	Inducer(s)	Reported pros, cons and main applications in P. putida		Ref.(s)
Positively regulated induction systems
XylS	Pm	m-toluate and derivatives	+ High expression levels + Extensively characterized + Cheap inducers	− Catabolite repression − Dose-dependent response in absence of inducer metabolization pathways − Bimodal response − Leaky expression	^{28,49,63,130–139}
XylS	Pm	m-toluate and derivatives	Applications: Expression of I-sceI, dCas9, trfA, the λ red operon, and recombinases in genome engineering tools; expression of toxic genes for controlled autolysis; production of recombinant antibody fragments and p-coumaric acid		^{28,49,63,130–139}
RhaRS	P_rhaB	l-rhamnose	+ No catabolite repression + No metabolization of rhamnose: dose-dependent response + Tight regulation + Non-toxic inducer	− Inhomogeneous response at intermediate inducer levels − Expensive inducers	^{132,138,140,141}
RhaRS	P_rhaB	l-rhamnose	Applications: Expression of dCas9 for CRISPRi and Cre for genomic deletions; production of p-coumaric acid		^{132,138,140,141}
AraC	P_BAD	l-arabinose	+ Characterization + No catabolite repression + No metabolization of arabinose: dose-dependent response + Tight regulation + Non-toxic inducer	− Inhomogeneous response at intermediate inducer levels − Poor arabinose uptake without AraE transporter − Expensive inducers	^132,142,143
AraC	P_BAD	l-arabinose	Applications: Production of p-coumaric acid		^132,142,143
Negatively regulated induction systems
LacI	Plac, PlacUV5, Ptac, Ptrc	Lactose, isopropyl β-d-1-thiogalactopyranoside (IPTG)	+ Extensively characterized + No metabolization of lactose or IPTG: dose-dependent response	− Toxicity of IPTG − Leaky expression − Expensive inducers	^{132,143–149}
LacI	Plac, PlacUV5, Ptac, Ptrc	Lactose, isopropyl β-d-1-thiogalactopyranoside (IPTG)	Applications: Expression of Bxb1 integrase for genomic integration; biodesulfurization; production of p-hydroxybenzoate, ethanol, and recombinant proteins		^{132,143–149}
TetR	Ptet	Anhydrotetracycline (aTc)	+ Tight regulation + No metabolization of inducer: dose-dependent response	− Unreliable functioning (probably due to unbalanced TetR levels) − Toxicity of aTc	^{143,150–152}
TetR	Ptet	Anhydrotetracycline (aTc)	Application: Tubulysin production		^{143,150–152}

TF transcription factor.