The overnight cultures in TSB at 25 °C of the ERL10460, ERL104253
and ERL032123 were serially diluted in sterile 0.85% saline (with the
dilution factor from 10−1 to 10−7). For each dilution, 20 μl of bacteria
solution was inoculated into each vial of the BacTrac™ 4000 containing
10 ml of TSB. Vialswere prepared in triplicate and incubated at 30 °C for
24 h. The impedance changesweremeasured and the time taken for this
impedance change to reach 1.5% was recorded. Trypticase soy agar
(TSA) plates were inoculated with 0.1 ml of 10−1, 10−2 and 10−3
dilutions, and incubated at 30 °C for 24 h. The number of colonies was
counted to provide the standard plate count (SPC) and a calibration
equation of SPC against the time for impedance change was calculated
by using the Microsoft Excel programme. The number of viable cells of
Y. enterocolitica could be determined by using the calibration equation