TABLE 2.

Phenotypic analysis of L. monocytogenes strains with prfA mutations

StrainPrfA genotypeHemolytic activityaPlaque sizebMotilityc
NF-L476WT100100d100
NF-L879L140F461.5 ± 225.378.9 ± 2.7d0.8 ± 28.5
NF-L1003ΔprfA20.8 ± 22.70114.2 ± 14.1
NF-L1009ΔprfA + pPL2i16.3 ± 19.10121.4 ± 14.7
NF-L1041ΔprfA + WTi75.6 ± 28.4100e148.6 ± 24.0
NF-L1042ΔprfA + L147Pi24.5 ± 10.30145.1 ± 28.7
NF-L1011ΔprfA + L140Fi564.0 ± 164.890.4 ± 2.2e46.4 ± 22.5
NF-L1006WT + pPL2i86.2 ± 27.6100f85.6 ± 11.8
NF-L1039WT + WTi187.7 ± 54.4109.1 ± 4.3f111.0 ± 13.4
NF-L1040WT + L147Pi82.2 ± 20.7107.0 ± 5.4f130.1 ± 22.8
NF-L1008WT + L140Fi884.1 ± 598.7104.1 ± 8.9f7.2 ± 26.7
NF-L1067L140F + L140Fi312.9 ± 35.9100.6 ± 4.9e4.3 ± 21.1
  • a Determined after 5 h of growth in BHI broth at 37°C; expressed as percentage ± standard deviation from at least three independent experiments, with WT set at 100%.

  • b Expressed as percentage ± standard deviation from four independent experiments.

  • c Soft agar (BHI-activated charcoal with 0.3% [wt/vol] agar) was inoculated with mid-log-phase bacterial cultures and incubated overnight at 37°C. Motility was measured as the diameter of the swimming colony minus that of a ΔflaA mutant and is expressed as percentage ± standard deviation from duplicate samples from two experiments, with WT set at 100%.

  • d Percent ± standard deviation with WT (NF-L476) set at 100%.

  • e Percent ± standard deviation with NF-L1041 set at 100%.

  • f Percent ± standard deviation with NF-L1006 set at 100%.