Significance of phage-host interactions for biocontrol of Campylobacter jejuni in food

Poultry meat is the main source of Campylobacter jejuni foodborne disease. Currently, no effective control measures prevent C. jejuni from contaminating poultry meat. However, post-harvest phage treatment is a promising biocontrol strategy that has not yet been explored. Here we identified phages capable of reducing C. jejuni at chilled temperature by a systematic screening of unique phages of our collection consisting of flagellotropic phages and phages dependent on capsular polysaccharides (CPSs) for infection. Interestingly, CPS phages showed varied killing efficiencies at 5 C-omicron in vitro, ranging from insignificant reduction to 0.55 log reduction. In contrast, none of the flagellotropic phages significantly reduced C. jejuni counts at low temperature. Phage adsorption at 5 C-omicron showed that flagellotropic phages bind reversibly and less efficiently to C jejuni than CPS phages, which may explain why flagellotropic phages did not reduce C jejuni. The CPS phages tested showed similar binding capacities. Thus, the varying effectiveness of CPS phages to reduce C jejuni counts may be attributed to other stages of the phage life cycle than phage binding. Finally, a phage cocktail of the two most effective phages (F356 showing 0.49 and F357 showing 0.55 log reductions, respectively) led to a 0.73 log reduction of C jejuni on artificially contaminated chicken skin. Our study shows that poly-phage treatment at 5 C-omicron can be more effective against C. jejuni compared to single phage application. A thorough understanding of phage-host interactions is prerequisite to further advance phage application as a post-harvest biocontrol strategy against C. jejuni. (C) 2016 Elsevier Ltd. All rights reserved.