PhD thesis

Assessment of low-dose radiotoxicity in microorganisms and higher organisms

Pic Muhammad Obeid

PhD student:
Muhammad H. Obeid
Dr. K. Fahmy (HZDR)

The toxicity of heavy metals and radionuclides cannot be assessed from environmental concentrations of the respective elements alone because many factors affect their bioavailability. The relevant parameters are largely unknown in the environment and molecular mechanisms of metal uptake not generally elucidated. We have initiated experiments that use the organism itself to determine the concentration threshold above which a metabolic response to the metal can be detected. This response can be accurately determined by microcalorimetry in complex synthetic and natural growth media. In this way, we study the chemitoxic and radiotoxic effects of heavy metals and radionuclides using a variety of bacteria including isolates from nuclear waste piles. The data are analysed in the context of the genetic background of the bacteria. The figure shows thermograms produced by bacteria that were isolated from a uranium mining waste pile as a function of uranyl concentration.