3D Chemical and Elemental Imaging by STXM Spectrotomography

• Main Authors: Wang, J., Karunakaran, C., Lu, Y., Hormes, J., Hitchcock, A. P., Prange, A., Institute for Microbiology and Virology, University of Witten/Herdecke, Witten, Center for Advanced Microstructures and Devices, Franz, B., Harkness, T., Obst, M.
• Format: Conference Proceeding
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; ABSORPTION SPECTROSCOPY; ALKALINE EARTH METAL COMPOUNDS; ALKALINE EARTH METALS; BACTERIA; CALCIUM; CALCIUM CARBONATES; CALCIUM COMPOUNDS; CALCIUM IONS; CARBOHYDRATES; CARBON COMPOUNDS; CARBONATES; CELL CONSTITUENTS; CELL WALL; CHARGED PARTICLES; COPPER; DISTRIBUTION; ELECTROMAGNETIC RADIATION; ELEMENTS; EUMYCOTA; FUNGI; IMAGE PROCESSING; IONIZING RADIATIONS; IONS; LIGHT SOURCES; MAPPING; METALS; MICROORGANISMS; NONMETALS; ORGANIC COMPOUNDS; OXYGEN COMPOUNDS; PARTICLE ACCELERATORS; PLANTS; POLYSACCHARIDES; PROCESSING; PROTEINS; RADIATION SOURCES; RADIATIONS; SACCHARIDES; SACCHAROMYCES; SACCHAROMYCES CEREVISIAE; SPATIAL DISTRIBUTION; SPECTROSCOPY; SULFATES; SULFUR; SULFUR COMPOUNDS; TRANSITION ELEMENTS; X RADIATION; X-RAY SPECTROSCOPY; YEASTS
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/1.3625342

Spectrotomography based on the scanning transmission x-ray microscope (STXM) at the 10ID-1 spectromicroscopy beamline of the Canadian Light Source was used to study two selected unicellular microorganisms. Spatial distributions of sulphur globules, calcium, protein, and polysaccharide in sulphur-metabolizing bacteria (Allochromatium vinosum) were determined at the S 2p, C 1s, and Ca 2p edges. 3D chemical mapping showed that the sulphur globules are located inside the bacteria with a strong spatial correlation with calcium ions (it is most probably calcium carbonate from the medium; however, with STXM the distribution and localization in the cell can be made visible, which is very interesting for a biologist) and polysaccharide-rich polymers, suggesting an influence of the organic components on the formation of the sulphur and calcium deposits. A second study investigated copper accumulating in yeast cells (Saccharomyces cerevisiae) treated with copper sulphate. 3D elemental imaging at the Cu 2p edge showed that Cu(II) is reduced to Cu(I) on the yeast cell wall. A novel needle-like wet cell sample holder for STXM spectrotomography studies of fully hydrated samples is discussed.