Campylobacter jejuni is one of the leading causes of foodborne diseases in Canada and the United States. C. jejuni can enter a viable but nonculturable (VBNC) state under stressful conditions. In this dormant state, it maintains reduced metabolic activity but cannot be cultivated on media. VBNC C. jejuni retains pathogenic potential due to its ability to resuscitate under appropriate conditions. Food industry mainly applies physical and chemical stresses to inactivate bacteria that are highly likely to induce bacteria to enter VBNC state. The objective of this study was to investigate the formation of VBNC C. jejuni in food processing and storage-related environment. C. jejuni isolates were induced under different conditions mimicking various food treatments, including 1) room temperature (22 °C), 2) low-temperature (4 °C), 3) aerobic stress, 4) starvation (phosphate buffered saline (PBS)). The dynamics of VBNC population over time were monitored using the plating assay combined with quantitative polymerase chain reaction coupled with propidium monoazide (PMA-qPCR). All the conditions tested were able to induce C. jejuni into the VBNC state. It was found that increasing temperature increased the induction rate of the bacteria. Moreover, induction in nutrient broth led to shorter induction times and higher survival rates compared to that in PBS. Finally, C. jejuni F38011 required extended time to be completely induced to VBNC compared to C. jejuni ATCC 33560. The presence of VBNC C. jejuni were verified using LIVE/DEAD BacLight Bacterial Viability Kit combined with confocal fluorescence microscope. This study demonstrated that C. jejuni can enter into the VBNC state during transportation, processing and storage of food products, posing a health risk to agri-food system.

Pierre-Luc Longchamps Longchamps

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