Thomas Leonardo
Mechanisms of accumulation and the biological impact of silver and cobalt on the micro-alga Coccomyxa actinabiotis.
Published on 12 December 2014
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Thesis presented December 12, 2014
Abstract :
A new green micro-alga species,
Coccomyxa actinabiotis, was recently discovered in a nuclear environment. This alga is highly resistant to ionizing radiation and accumulates some radionuclides. Thanks to its properties, the development of a new biotechnology based on
C. actinabiotis for the clean-up of nuclear liquid effluents is under consideration. Our work aims more specifically at describing and understanding the alga’s silver and cobalt accumulation processes as well as the biological impact of these metals, which are the main gamma emitting radionuclides present in liquid effluents issuing from French nuclear facilities.
This study was carried out using four complementary approaches: (a) Kinetics and equilibriums of silver and cobalt uptake were assessed by ICP-MS analysis; (b) The subcellular distribution of the metals was mapped at a nanometric scale using synchrotron X-ray fluorescence and transmission electron microscopy; (c) The speciation of silver and cobalt taken up by the alga was assessed by synchrotron X-ray absorption spectroscopy and X-ray diffraction; (d) The biological impact of these metals on the alga was investigated, in particular the physiological and metabolic perturbations they induce.
Altogether, these results unveiled some of the processes involved in silver and cobalt accumulation by
C. actinabiotis.
Keywords:
Micro-alga,
Coccomyxa actinabiotis, metals, silver, cobalt, accumulation mechanisms, metal toxicity, subcellular distribution, speciation, biological impact
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