Microbial survival mechanisms in acidic and cold environments

Microorganisms employ various biological mechanisms to survive in extreme or low-temperature environments, impacting both human health and food safety.

In the human stomach, certain bacteria like Helicobacter pylori can withstand highly acidic conditions (pH 1–2). They utilize sophisticated strategies such as acid acclimation, ammonia production, and protective mucus niches to colonize the gastric mucosa.

Regarding food preservation, refrigeration does not create a sterile environment. Psychotrophic bacteria, including genera such as Pseudomonas, Acinetobacter, and Listeria, can survive and multiply at temperatures between 0 and 7 °C due to specialized cell membranes and cold-shock proteins.

Thermal processing serves as a primary defense against pathogens like Salmonella and Listeria. Heat works by denaturing essential proteins and enzymes and compromising cellular membranes. While vegetative cells are highly susceptible to protein denaturation, bacterial spores exhibit significantly higher resistance and require more intense heat treatments to ensure safety.