Effect of chicken meat environment on gene expression of Campylobacter jejuni and its relevance to survival in food.

Poultry meat is the major food source responsible for gastrointestinal infections caused by the human pathogen Campylobacter jejuni. Even though C. jejuni does not grow below 30 °C, the bacterium survives on raw meat surfaces at refrigerated temperatures and thus poses a risk to the consumer. Previously, we have shown that chicken meat juice prolongs survival of C. jejuni at 5 °C compared to laboratory medium, suggesting that compounds present in meat juice influence adaptation to low temperatures. In the present study we have used chicken meat juice to identify C. jejuni genes that are differentially expressed in a typical chicken meat environment encountered by consumers. The analysis showed that chicken meat juice increased expression of luxS involved in quorum sensing, as well as a gene involved in O-linked flagellin glycosylation in C. jejuni, while expression of haemin uptake and the peroxide stress response genes were reduced. Furthermore, we propose that LuxS may play a key role in adaptation to the chicken meat juice environment, as lack of the luxS gene reduces the ability of C. jejuni to survive in chicken meat juice at low temperature. Finally, our data suggest that part of an ABC transport system is induced and we speculate that uptake of cryoprotectants may be important for C. jejuni to adapt to low temperature. In summary, we found that C. jejuni has a specific but limited transcriptional response to chicken meat juice and that luxS has an impact on the prolonged survival of C. jejuni in this important environment in the food chain.