Study of gamma radiation effects on the metabolic activity of Escherichia coli ATCC 25922 cells.

Investigating how Escherichia coli responds to gamma radiation enhances understanding of microbial functional mechanisms by elucidating how bacterial cells cope with ionizing radiation-induced DNA damage and oxidative stress. E. coli is a Gram-negative bacterium found in the intestinal microbiota of humans and widely used as a model organism in radiation microbiology. Exposure to ionizing radiation can impair cellular integrity, potentially leading to metabolic shifts and a loss of metabolic capacity. In this study, the effects of gamma radiation on E. coli populations were evaluated using MTT reduction assays as an operational proxy for metabolic activity rather than strict replicative viability. Irradiation experiments were performed using a fixed dose rate of 6 Gy/h with variable absorbed doses (0.05 to 40 Gy), as well as variable dose rates at a fixed dose of 6 Gy. Bacterial cells were suspended in BHI broth and incubated to allow biofilm formation. The results showed distinct metabolic profiles in planktonic and biofilm-associated cells at a constant dose rate, with dose-dependent alterations in metabolic output during biofilm formation.