Table 1

Pathogenicity of P. aeruginosa PA14 mutants on various hosts

Strain Isolation NumberPathogenicity phenotypes Gene in which TnphoA was inserted or closest published homologue (organism; GenBank accession no.)
C. elegans killing LT50, h*Growth in Arabidopsis leaf% Mouse mortality (n) 5 × 105
PA1439.6  ±  2.82.9  ×  107100  (>16)
12A1 >901.7  ×  10650  (8)lasR (P. aeruginosa; P25084)
35H7d >901.2  ×  104NT§gacA (P. aeruginosa; Q51373)
48D9 >901.0  ×  10450  (8)lemA (P. syringae; P48027)
50E12 >902.0  ×  1050  (16)ptsP (A. vinelandii; Y14681)
35A9 61.2  ±  0.87.6  ×  10653  (17)mtrR (N. gonorrhoeae; P39897)
44B1 62.7  ±  2.31.0  ×  10756  (18)No matches
41C1 51.1  ±  0.32.4  ×  10581  (16)aefA (E. coli; P77338)
41A5 46.2  ±  0.41.3  ×  104100  (8)No matches
  • * A mutant is considered attenuated in nematode pathogenicity if the mean time required to kill 50% of the worms feeding on it (LT50 from three to four replicates) is 2 SDs less than the LT50 of parental PA14 in the same experiment; for calculations of LT50 see ref. 2. A LT50 > 90 is given to mutant strains that kill less than 30% worms at 90 h. 

  • Colony-forming unit per cm2 leaf area of bacterial counts at 4 days postinoculation of 103 bacteria; means of four to five samples. Mutants are defined as less pathogenic when the mean value of bacterial counts is 2 SDs lower relative to wild type within the same experimental set. 

  • Six-week-old male inbred strain mice (from The Jackson Laboratories), weighing between 20 and 30 g, were injected with 5 × 105 bacterial cells. n, total number of mice tested. The number of animals that died of sepsis was monitored each day for 7 days. 

  • § Another gacA mutant 1D7 was isolated independently from a plant screen. Mutant 1D7 has been tested on mice and showed 50% mortality (9).