Using gene expression profiling, Malone et al. (2008) isolated
>30 genes which are up-regulated, and >30 which are downregulated,
following exposure to high yet sub-lethal pressures.
Benito et al. (1999) found significant differences in pressure
sensitivity (>4 log) of different E. coli O157:H7 isolates suspended in
buffer at 500 MPa for 15 min, as well as differences in heat sensitivity
and pH in combination with HPP. While the basic virulence
gene profile for the 39 isolates used in this study were provided by
those donating them, genomic DNA sequence for most of the 39
STEC is currently unknown. Genomic DNA sequencing, in combination
with transcriptomics and proteomics, may elucidate which
genes and proteins may be responsible for the >25 fold difference
in resistance to high pressure.
In the study, only one strain (B-59801) carries neither stx2 nor
eae genes, and does not belong to the big six serovars. This strain
has a medium HPP resistance and could be safer to use as a surrogate
for laboratory safety purposes. In addition, B-59801 also had moderate radiation resistance as noted by Sommers et al. (2015),
therefore B-59801 may be used as a surrogate in both HPP and
irradiation studies.