Isolation and transposon mutagenesis of a Pseudomonas putida KT2442 toluene-resistant variant: involvement of an efflux system in solvent resistance.
A toluene-resistant variant of Pseudomonas putida KT2442, strain TOL, was isolated after liquid cultivation under xylene followed by toluene for 1 month in each condition. Almost all the populations of the variant strain formed small but readily visible colonies under toluene within 24 h at 30 degrees C. The toluene-resistant strain also showed an increase in resistance to some unrelated antibiotics. Several toluene-sensitive Tn5 mutants have been isolated from the toluene-resistant strain and showed various levels of sensitivity. Most of these mutations did not cause significant changes in antibiotic resistance; however, one of the mutants (TOL-4) was highly susceptible to both organic solvents and various antibiotics, especially beta-lactams. Sequencing analysis revealed that the mutation in TOL-4 had been introduced into a gene that may encode a transporter protein of an efflux system. This efflux system is very similar to one of the multidrug efflux systems of Pseudomonas aeruginosa. These observations indicate that a multidrug efflux system plays a major role in the organic solvent resistance of P. putida TOL. However, several other genes may also be involved.
Fukumori
F
F
DEEPSTAR Group, Japan Marine Science and Technology Center, Yokosuka. fukumori@jamstec.go.jp
Hirayama
H
H
Takami
H
H
Inoue
A
A
Horikoshi
K
K
D000222:Adaptation, Physiological; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D004352:Drug Resistance, Microbial; D014644:Genetic Variation; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016958:Pseudomonas putida / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D012997:Solvents; D014050:Toluene / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D012997:Solvents; D014050:Toluene