Psychrotolerant spoilage bacteria enhanced Campylobacter jejuni culturability on refrigerated chicken meat

Campylobacter jejuni is a leading cause of bacterial foodborne illness, with poultry as a major transmission vehicle. The bacterium can enter a viable but non-culturable (VBNC) state, which complicates detection using culture-based methods. While cold and oxidative stress are known VBNC inducers, the role of poultry-associated microbiota in influencing C. jejuni culturability and viability during refrigeration is poorly understood. This study characterized the effect of retail chicken microbiota on C. jejuni over 10 days of cold storage in aerobic and vacuum conditions. We profiled microbiota from chicken breasts in aerobic, modified atmosphere, and vacuum packaging, and from whole chicken under aerobic packaging conditions. Microbiota composition varied with packaging, with Pseudomonas, Brochothrix, and Acinetobacter dominating in aerobic, and Lactococcus and Leuconostoc in vacuum conditions. These genera were isolated and assessed for growth and biofilm formation at 4 °C. Psychrotolerant isolates were whole genome sequenced and used to evaluate their effect on C. jejuni viability and culturability on chicken breast. Three microbiome treatments, including T1 (Pseudomonas, Brochothrix, Acinetobacter), T2 (Lactococcus, Leuconostoc), and T3 (T1 + T2), were co-inoculated with C. jejuni and stored at 4 °C. Viability was assessed by viability qPCR and culturability by plating on Campy Cefex and mCCDA agars. Campy Cefex recovered significantly more (0.74 log₁₀) C. jejuni than mCCDA on day 10 but underestimated viable cell concentration by 2.87 log₁₀. All microbiome treatments improved culturability by > 1 log under aerobic conditions, but not vacuum, highlighting the need to further explore the interactions between non-pathogens and Campylobacter in meat stored aerobically. Microbiome effects on viability were modest and variable. Overall, culture-based methods underestimated C. jejuni viability, underscoring the need for complementary molecular quantification in food safety assessments.