0.85% w/v NaCl, pH 6.8) on MRSA followed by incubation at 30 °C
for 2 days.
Foodborne pathogens E. coli O157 EDL-932 and L. monocytogenes
Scott A are strains retained in our collection. Working cultures of both
strains were maintained in tryptone soy agar (TSA) (Scharlau). Inocula
were propagated in tryptone soy broth (TSB) and incubated at 37 °C
for 24 h. Cells were harvested by centrifugation (10,000 ×g, 10 min),
the pellet washed twice in sterile saline water, and finally resuspended
in sterile distilledwater. The cell densitywas determined by total viable
count after plating the serial dilutions (in peptone/saline) on TSA
followed by incubation at 37 °C for 24 h.
All strainswere maintained in frozen cryovials containing beads and
cryopreservatives at −80 °C (MicroBank™). They were sub-cultured
twice in 10 ml MRS or TSB broth for activation of L. plantarum or
L. monocytogenes and E. coli, respectively, before use.