Comprehensive element analysis of prokaryotic and eukaryotic cells as well as organelles by ICP-MS

Abstract

Elemental abundances of prokaryotic and eukaryotic cells as well as organelles were provided as the number of atoms per cell (or organelle). In order to examine the specific uptake of vital elements by cells, E. coli cells were grown in different media and harvested at several time points during the cell growth and proliferation. The major-to-ultratrace elements in the cells were determined by micro-flow injection (µFI)-ICP-MS after microwave-assisted acid digestion of less than 10 mg of dry weight sample. Cyanobacteria and chlorella were also cultivated to compare elemental abundance differences among species. In addition, to further examine the localization and utilization of vital elements in the cells, chloroplasts and mitochondria were isolated from the tissues of spinach leaves, potato tuber, and bovine liver by density-gradient centrifugation using Percoll. The concentration data obtained by ICP-MS measurements were normalized to a per cell (or organelle) basis, taking into account the cell size and water content. Among about 60 elements detectable by ICP-MS, more than 30 elements were quantitatively determined, and it was clearly found that essential elements participating in specific vital functions such as redox reactions were highly accumulated in the microorganisms and organelles.