Salmonella must be viable in order to attach to the surface of prepared vegetable tissues

Aims: The aims of the current study were to explore the site of bacterial attachment to vegetable tissues and to investigate the hypothesis that Salmonella must be living in order to attach to this site(s). Methods and Results: Scanning electron micrographs of intact potato cells showed that Salm. serotype Typhimurium attached to cell-wall junctions; suggesting a high-level of site selectivity. Inactivation of Salm. Typhimurium using heat, ethanol, formalin or Kanamycin resulted in cells that could be no longer attached to these sites. Attachment of a Gfp⁺ strain of Salm. Typhimurium to cell-wall material (CWM) was examined via flow cytometric analysis. Only live Salm. Typhimurium attached to the CWM. Conclusions: Salmonella serotype Typhimurium must be metabolically active to ensure attachment to vegetable tissues. Attachment preferentially occurs at the plant cell-wall junction and the cell-wall components found here, including pectate, may provide a receptor site for bacterial attachment. Significance and Impact of the Study: Further studies into individual plant cell-wall components may yield the specific bacterial receptor site in vegetable tissues. This information could in turn lead to the development of more targeted and effective decontamination protocols that block this site of attachment.