The Influence of Selenourea and of Colloidal Selenium on the Survival of E. Coli B/r after X-irradiation

Summary

E. coli B/r irradiated in the presence of 5 × 10⁻² M selenourea shows an increased survival when irradiated in air and the opposite effect in nitrogen.

The anoxic sensitization appears to be due to colloidal selenium which is formed by radiation from selenourea, whereas this last seems to be a protector most active in the presence of oxygen. This statement is based on the following experimental results:

1. 5 × 10⁻² M selenourea solutions show the same effect when pre-irradiated with 150 krads before mixing with bacterial suspensions;

2. colloidal selenium separated from a repeatedly-irradiated selenourea solution and resuspended in buffer is more active than the original selenourea solution in sensitizing anoxic bacteria and is completely ineffective on bacteria irradiated in air;

3. the sensitization of anoxic bacteria is decreased by resuspending colloidal selenium in fresh selenourea solution.