How Salmonella Works Under Osmotic and Desiccation Stresses

Salmonella remains one of the leading threats in foods with reduced water activity, where it can survive for long periods and cause outbreaks. Its persistence stems from a wide array of adaptive strategies shaped by the selective pressures imposed by low-moisture foods. Under osmotic or desiccation stress, the bacterium quickly adjusts its gene expression, activates DNA repair systems, and alters its growth dynamics, often forming elongated cells that conserve energy. At the same time, it reshapes its membranes, accumulates protective molecules such as trehalose, proline, and betaine, and frequently organizes into biofilms that shield cells from harsh conditions. These protective responses are closely tied to its disease-causing potential, because stress signals also influence virulence factors, secretion systems, fimbriae, and flagella, ultimately making the pathogen more capable of establishing infection. Stress exposure can further trigger cross-protection, enhancing resistance to heat, disinfectants, and other common barriers in food processing. In some cases, cells enter a dormant, viable but non-culturable state, remaining undetectable until favorable conditions allow their revival. Together, these mechanisms reveal the extraordinary resilience of Salmonella in dry food environments and highlight the challenge of ensuring safety in products that are often ready to eat. A deeper understanding of these adaptations is essential to develop more effective control strategies and reduce the burden of salmonellosis worldwide. In this review, we provide a detailed discussion of the morphological, transcriptional, and metabolic aspects of Salmonella's response to osmotic and desiccation stresses.