Energy-dispersive X-ray analysis of the extracellular cadmium sulfide crystallites of Klebsiella aerogenes

Holmes, Justin D., Smith, Peter R., Evans-Gowing, Richard, Richardson, David J. ORCID:, Russell, David A. and Sodeau, John R. (1995) Energy-dispersive X-ray analysis of the extracellular cadmium sulfide crystallites of Klebsiella aerogenes. Archives of Microbiology, 163 (2). pp. 143-147. ISSN 0302-8933

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Klebsiella aerogenes forms electron-dense partieles on the cell surface in response to the presence of cadmium ions in the growth medium. These particles ranged from 20 to 200 nm in size, and quantitative energy dispersive X-ray analysis established that they comprise cadmium and sulfur in a 1:1 ratio. This observation leads to the conclusion that the particles are cadmium sulfide crystallites. A combination of atomic absorption spectroscopy, inductively coupled plasma mass spectrometry, and acid-labile sulfide analysis revealed that the total intracellular and bound extracellular cadmium:sulfur ratio is also 1:1, which suggests that the bulk of the cadmium is fixed as extracellular cadmium sulfide. The tolerance of K. acrogenes to cadmium ions and the formation of the cadmium sulfide crystallites were dependent on the buffer composition of the growth medium. The addition of cadmium ions to phosphate-buffered media resulted in cadmium phosphate precipitates that remove the potentially toxic cadmium ions from the growth medium. Electrondense particles formed on the surfaces of bacteria grown under these conditions were a combination of cadmium sulfide and cadmium phosphates. The specific bacterial growth rate in the exponential phase of batch cultures was not affected by up to 2mM cadmium in Tricine-buffered medium, but formation of cadmium sulfide crystallites was maximal during the stationary phase of batch culture. Cadmium tolerance was much lower (10 to 150 μM) in growth media buffered with Tris, Bistris propane, Bes, Tes, or Hepes. These results illustrate the importance of considering medium composition when comparing levels of bacterial cadmium tolerance.

Item Type: Article
Uncontrolled Keywords: cadmium sulfide,energy dispersive x-ray analysis,heavy metals,klebsiella aerogenes,microbiology,biochemistry,molecular biology,genetics ,/dk/atira/pure/subjectarea/asjc/2400/2404
Faculty \ School:
Faculty of Science > School of Biological Sciences
UEA Research Groups: Faculty of Science > Research Groups > Organisms and the Environment
Faculty of Science > Research Groups > Molecular Microbiology
Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry
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Depositing User: LivePure Connector
Date Deposited: 15 Jul 2022 12:30
Last Modified: 14 May 2023 13:30
DOI: 10.1007/BF00381789

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