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The unique role of intracellular calcification in the genus Achromatium

Lookup NU author(s): Emeritus Professor Neil Gray


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Achromatium are found in freshwater and brackish sediments where, as giant sulfur-oxidizers, they play a key role in the carbon and sulfur cycles of the sediments they inhabit. The most striking feature of this genus is its enigmatic precipitation of intracellular calcite. Past explanations, for this process have include the dissolution of stored calcite to regulate acidity generated by H2S oxidation; the use of calcite as a buoyancy regulating mechanism, the use of calcite or as a source of electron acceptor in “carbonate respiration” and the use of calcification to generate CO2 for carbon fixation. However, more recent in situ physiological studies and detailed characterisation of the environments inhabited by these organisms have indicated a possible role for intracellular calcification in the dissolution of sulfide minerals. It is proposed that this unique adaptation of Achromatium is a means of overcoming a challenge not faced by other giant sulfur bacteria, namely, inherently low levels of free sulfide in their sedimentary environment.

Publication metadata

Author(s): Gray ND

Editor(s): Shively JM

Publication type: Book Chapter

Publication status: Published

Book Title: Inclusions in Prokaryotes

Year: 2006

Pages: 299-309

Series Title: Microbiology Monographs

Publisher: Springer-Verlag

Place Published: Berlin


DOI: 10.1007/3-540-33774-1_11

Library holdings: Search Newcastle University Library for this item

ISBN: 9783540262053