Application of micro-PIXE technique to uptake study of cesium by Saccharomyces cerevisiae

We examined the accumulation and distribution of Cs, and the presence of other elements in yeast (Saccharomyces cerevisiae) cells by the micro-PIXE (particle induced X-ray emission) system developed at the TIARA facility, JAERI, and by energy dispersive spectroscopy (EDS) coupled to a scanning electron microscope. The effects of Cs on yeast growth were determined by measuring the optical density at 600 nm. Addition of 1 mM Cs did not have any effect on the growth of the yeast. Micro-PIXE analysis of cells grown in the presence of Cs showed that Cs was uniformly distributed in the cells. Using PIXE, Cs, P, K and Fe can be detected, whereas only P and S can be determined by the EDS. Cells exposed to Cs showed an increase in Cs peak intensity, and decrease in P, K and Fe with time. These results suggest that micro-PIXE is a useful technique to detect low concentration of toxic elements in microorganisms as well as to monitor their changes as function of growth. (C) 2003 Elsevier B.V. All rights reserved.