Table 2.

Organic solvent tolerance of P. aeruginosa on agar plates

StrainRelevant efflux phenotypebGrowth ona:
n-Hexanep-XyleneToluene
PAO1MexAB-OprM+ + (S)+ (S)
K1119MexAB-OprM
OCR1MexAB-OprM++c + (C)+ (C)
ML5087MexAB-OprM+ + (S)+ (S)
K1110MexAB+ OprM
K1112d MexAB-OprM++ + (C)+ (C)
K1131MexAB-OprMMexCD-OprJ+
K1117MexAB-OprMMexEF-OprN+
PAO6609MexAB-OprM+ ++
K1032MexAB-OprM
  • a Bacteria (5 μl) were spotted onto LB agar, overlaid with organic solvent, and incubated overnight at 30°C as outlined in the text. +, growth; −, no growth. In parentheses are the results of EOP experiments in which 100-μl cell cultures were plated on the surfaces of LB agar plates, overlaid with organic solvent, and likewise incubated overnight. C, confluent growth; S, single-colony growth. The log Pow values of the solvents were as follows: n-hexane, 3.9;p-xylene, 3.1; toluene, 2.8.

  • b The status of those efflux systems (components) that are known to be expressed and, thus, potentially contribute to the organic solvent tolerance of the indicated strains is highlighted.

  • c High-level expression of MexAB-OprM.

  • d This strain yielded scattered colonies after 72 h of incubation in the presence of toluene.