2.4. Recovery of the surviving bacteria
The treated samples were retrieved to recover the survivors by
adding 10ml of 0.1% PWto each sample bag and mixed for 2min in a
mechanical stomacher (Model Bag Mixer 100W, Inter Science Co.,
France). The filtrate, after proper decimal dilutions, was plated in
triplicate onto Tryptic Soy agar (TSA, BD/Difco), SMAC, and TSA/R
(TSA plates containing 100 mg/L rifampicin) plates for total aerobic
bacteria, the “Big Six” non-O157 STECs and E. coli O157:H7 count,
respectively. The plates were maintained at room temperature for
2 h to allowthe injured cells to recover (Huang, 2004; Solomon et al.,
2006), and then incubated at 37 C for 24 h.