| This Andy Warhol-like image is actually a composite of pictures
of a single bacterial cell taken on a VG-HB603 STEM (Scanning Transmission
Electron Microscope). The upper left quadrant is a dark-field image of
a whole cell mount of Desulfotomaculum auripigmentum (an organism
named for its ability to precipitate the yellow mineral As2S3). Moving
clockwise, the other quadrants show X-ray maps of As2S3, arsenic, and
sulfur, respectively. The As2S3 map is an overlay of the arsenic and sulfur
profiles. Magnification, x20,000. The length of the bacterium is approximately
3 microns. The ability of this organism to precipitate As2S3 is tightly
coupled to its ability to use arsenate and sulfate as terminal electron
acceptors in anaerobic respiration. (see Newman et al., 1997 Appl. Environ.
Microbiol. 63:2022-2028) |
