Transcriptional dynamics during the transition from culturable to viable but non-culturable states in Campylobacter jejuni

Abstract

Abstract Background Campylobacter jejuni is a major foodborne bacterial pathogen that poses substantial global public health challenges. Under environmental stresses, C. jejuni can enter a viable but non-culturable (VBNC) state that enables persistence under adverse conditions. Despite its potential implications for bacterial survival and food safety, the transcriptional mechanisms underlying VBNC induction in C. jejuni remain poorly understood. Therefore, this study aimed to characterise transcriptional alterations associated with the VBNC state induction under distinct environmental stress conditions using genome-wide gene expression profiling. Methods Culturable cells of C. jejuni strain NCTC11168 were exposed to three stress conditions, including high osmotic pressure (7% NaCl), low pH (pH 4.0), or low temperature (4 °C) to induce the VBNC state. Further, transcriptional changes associated with VBNC-state induction were analysed using RNA sequencing (RNA-Seq) followed by Gene Ontology Annotation (GO), Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway, and STRING network analyses. Results The RNA-Seq analysis revealed a distinct transcriptional alteration of C. jejuni under three environmental stress conditions, where high transcriptional response under low pH, followed by NaCl, respectively, and low-temperature stress induced minimal alteration. Our result also showed that peptidyl-tRNA hydrolase ( pth ) was the only gene consistently downregulated across all stress conditions, suggesting a potential role in the early stages of VBNC induction in C. jejuni . The GO analysis showed condition-specific functional enrichment, including broad stress and metabolic responses under osmotic stress and more focused regulatory and survival-related processes associated with VBNC formation. KEGG pathway and STRING network analyses further revealed coordinated modulation of central metabolism, translation, and motility-related functions. Conclusions These findings provide novel insights into the transcriptional landscape associated with the VBNC state in C. jejuni . The results suggest that the VBNC state induction is accompanied by coordinated modulation of pathways involved in protein translation, tRNA metabolism, and central metabolic pathways. These findings also indicate that transcriptional reprogramming enables C. jejuni to physiologically adapt and persist under adverse environmental conditions.