Transcriptomic analysis of Listeria innocua response to a green food sanitizer: presumable viable but nonculturable state induction

Viable but nonculturable (VBNC) state physiologically enables numerous bacteria such as Listeria to survive adverse conditions while evading conventional microbiological detection. Molecular mechanisms underlying this phenomenon are still poorly understood. Using RNA-seq, this study investigated transcriptomic profiles of L. innocua in VBNC state induced by a green sanitizer formulation based on a natural polyphenol gallic acid amended with hydrogen peroxide and lactic acid. Compared with non-treated culturable bacteria VBNC cells revealed 616 differentially expressed genes, 324 (53%) upregulated and 292 (47%) downregulated ones. Functional enrichment analysis highlighted broad downregulation of primary metabolism, including glycolysis, lipid metabolism and amino acid biosynthesis, alongside suppression secondary metabolism and ribosome channels, consistent with strategic resource conservation and metabolic downscaling. In spite of the proliferation arrest, the VBNC L. innocua unexpectedly upregulated key cell division genes (e.g., ftsL , zapA , e zrA ) along with SOS-induced division inhibitor, y neA and differential modulation of SOS associated DNA repair genes ( lexA, uvrA, recQ, recF and recN ) This apparent paradox might presumably support resuscitation potential, where removal of a blocking element could restore growth. These changes suggest coordinated nucleotide excision repair alongside stress response. Notably, the general stress response alternative sigma factor SigB, its regulators and sigma related genes like dltX were upregulated, pointing to its potential role factor in orchestrating the entry to VBNC state. Collectively, the study suggests that L. innocua responded to sanitizer application through fine-tuned global changes, including metabolic and translational downscaling, general stress response and a presumably reversible SOS-induced cell division arrest amid genomic maintenance. Altogether these coordination may facilitate reduced energy expenditure while maintain cellular function, hence survival as manifested as VBNC state.