## 6 Conditions for VBNC _L. monocytogenes_ Resuscitation  
The process of resuscitation is defined as the conversion of non-culturable cells into culturable cells without any change in cell numbers [14]. The resuscitation of VBNC _L. monocytogenes_ was found to occur at relative humidity close to 100%, but not in a dry environment and possibly on cheese find, but this was not unequivocally demonstrated. Regain of virulence was excluded by an experiment with human colon cells (HT-29) and in a murine model, but pre-incubation in embryonated chicken eggs restored pathogenicity. Models of VBNC _L. monocytogenes_ formation in human epithelial cells have suggested that subpopulations of unculturable cells rega \begin{table}
\begin{tabular}{c c c} \hline \hline
**VBNC Inducing** & \multicolumn{2}{c}{**Gene(s) or Protein(s)**} \\
**Condition** & **UPEgulated** & **Downregulated** & **Reference** \\ \hline \multirow{8}{*}{Starvation} & amino acid metabolism; & autolysins _lmo0394_, _p60_, _aut_, _lmo1215_, _lmo1521_, _lmo2522_, _ami_, _namA_ \\  & mannose, and metal ions; & nucleotide and coenzyme biosynthesis, \\  & protein translation and & transcription regulation, \\  & folding; transport of & uptake of phosphate and some \\  & carnitine/glycine betaine & carbohydrates, \\  & compatible solutes; & cell envelope biosynthesis and maintenance, \\  & glutathione metabolism; & cell division, \\  & half SigB regulon & energy production, protein secretion \\  & proteins associated with & ribosomal functions RpsZ, \\  & RpmI, Lmo1306, BetL, \\  & Lmo2564, RplX, RpmD, \\  & RpIT, RplO, RnpA, \\  & Lmo0208 & \\ FeSO\({}_{4}\) exposure & transcription factors _rpoC_, _rpoB_, and _rpoD_ & _lmo0668_, _trxA_, _trxB_, _lmo0593_, response genes \\  & & _lisK_, _lmo0539_, _lmo1502_, _lmo0521_, _lmo0913_, \\  & & [19] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: UPEgulated and downregulated gene clusters and proteins in VBNC cells of _L. monocytogenes_. Some studies used conventional culture media to demonstrate resuscitation of VBNC cells, such as TSAYE and TSBYE, BHI broth, TSB added with pyruvate or Tween 80, pasteurized milk, and half Listeria Fraser broth supplemented with 0.1% sodium pyruvate with long incubation times [14; 19; 20; 51]. However, in one study, resuscitation of chlorine and PAA-treated _L. monocytogenes_ did not occur in TSB, TSB supplemented with 0.3% of sodium pyruvate or 100 U/mL of catalase, and synthetic medium M9 salts (Becton Dickinson) supplemented with 0.4% glucose and 0.5 mM of each of the 20 amino acids previously reported to stimulate resuscitation. In addition, cell-free supernatants from logarithmic phase cultures were tested as resuscitation media without success [47]. Resuscitation of VBNC _L. monocytogenes_ induced by disinfectants was obtained by incubating 1 mL of lettuce homogenate in BPW in 9 mL of half Listeria Fraser broth, supplemented with 0.1% of sodium pyruvate, incubating for 20 h at 37 \({}^{\circ}\)C and then transferring 100 uL of the culture to 9 mL of Fraser supplemented with 0.1% sodium pyruvate incubated for 24 h at 37 \({}^{\circ}\)C. Samples were considered positive when the medium turned black. To confirm resuscitation, positive samples were streaked onto agar _Listeria_ Ottaviani Agosti (ALOA) and OCLA, and at least two typical _L. monocytogenes_ colonies were tested by _hly_ PCR after DNA extraction by boiling [20]. It was also reported that nutrient supplementation in culture media and non-embynonated chicken eggs did not allow the resuscitation of the VBNC forms of _L. monocytogenes_ EGDe generated by prolonged starvation in water. Instead, inoculation into embryonated chicken eggs of the isogenic GFP-expressing VBNC variant exhibited growth two days after inoculation. The resulting cells showed the presence of a cell wall, were rod-shaped, and could infect human trophoblasts (JEG-3) and hepatocytes (HepG2) after 6 h of contact with polymerization of host actin tails as efficiently as vegetative cells. This demonstrated that VBNC forms of _L.