Fig 1.

Selective enrichment of different food-borne pathogens toward HHP resistance (at 20°C). For each strain, four independent axenic cultures were iteratively exposed to progressively intensifying pressure shocks (15 min; 20°C), with intermittent resuscitation and growth of the survivors. Line graphs (-♢-) present the inactivation during the stepwise selection regimen with 10- or 25-MPa increments and are expressed as the logarithmic reduction factor [i.e., log(N₀/N)]. At the end of the selection regimen, the most HHP-resistant clone that had enriched in the corresponding cultures was isolated, and its acquired HHP resistance (black bars) was determined and compared to that of the original parent strain (white bars). Results shown in the bars are expressed as mean values ± standard deviations of three independent replicates. ND as well as the abrupt end of a line graph at pressures below 800 MPa indicate that the corresponding N fell below the detection limit, which was 10 or 200 CFU/ml for results shown in bars or line graphs, respectively.