Table 3.

Desiccation tolerances of Listeria monocytogenes strain 568 and its phosphotrehalase mutant 568:ΔTreAa

Treatment568568:ΔTreA
Lag time (h)Specific growth rate (h−1)Lag time (h)Specific growth rate (h−1)
Untreated4.36 ± 0.640.882 ± 0.0394.56 ± 0.410.855 ± 0.029
Desiccated27.57 ± 0.90*0.861 ± 0.01823.24 ± 0.75*0.878 ± 0.022
  • a Cells (∼106 CFU) were air dried for 2 h in the bottom of 12-well tissue culture plates and then desiccated for 14 days at 16% RH and 20°C. Following desiccation, BHI was added to the wells and growth of untreated (control) and desiccated cells at 30°C monitored by measuring absorbance at 30-min intervals. Analysis of growth curves was done using DMFit (version 2.1; http://www.ifr.ac.uk/safety/dmfit/). *, significant difference (P < 0.05) between the means from triplicate experiments as determined by Student's t test.