Calcium carbonate spherolites and sulphur granules
Achromatium oxaliferum (Schewiakoff 1893), a large colorless sulpher bacterium. The larger refractile spherical structures are calcite spherolites and the small globules adhering to them are granules of elemental sulphur. Collected from bottom sediments of a stagnant freshwater pond near Boise, Idaho. This image was taken by William Bourland. He now uses a Zeiss Axioskop 2 with Spot Insight and Spot Flex CCD cameras (Diagnostic Instruments). Image copyright: William Bourland, image used under license to MBL (micro*scope).
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From the collection
Freshwater and Terrestrial Microbes of Idaho (USA) and Elsewhere
|Description of Achromatium oxaliferum: Achromatium oxaliferum was described by Schewiakoff (1893).Its large cells contain large CaCO3 inclusions occurring together with much smaller sulfur granules. The cells are spherical, ovoid, or cylindrical. Divisionis by constriction. The cells are slowly motile on solid surfaces only. Attempts at culture have been unsuccesful. A particular environment is apparently required by the sulfide-oxidizing, nonphotosynthetic bacteria such as Beggiatoa, Thiothrix, Achromatium, Macromonas, Thiovulum, Thiospira, and a few others. Their habitats appear to be areas where the gradients of both hydrogen sulfide and oxygen are overlapping or, as in running waters, where the hydrogen sulfide-providing sediment is covered by running water containing oxygen. |