The impact of heat treatment on E. coli cell physiology in rich and minimal media considering oxidative secondary stress.

Aims: This study investigates the cell physiology of thermally injured bacterial cells, with a specific focus on oxidative stress and the repair mechanisms associated with oxidative secondary stress.

Methods and results: We explored the effect of heat treatment on the activity of two protective enzymes, levels of intracellular reactive oxygen species, and redox potential. The findings reveal that enzyme activity slightly increased after heat treatment, gradually returning to baseline levels during subculture. The response of Escherichia coli cells to heat treatment, as assessed by the level of superoxide radicals generated and redox potential, varied based on growth conditions, namely minimal and rich media. Notably, the viability of injured cells improved when antioxidants were added to agar media, even in the presence of metabolic inhibitors.

Conclusions: These results suggest a complex system involved in repairing damage in heat-treated cells, particularly in rich media. While repairing membrane damage is crucial for cell regrowth and the electron transport system plays a critical role in the recovery process of injured cells under both tested conditions.