Article

BioMetals

, Volume 20, Issue 3, pp 291-302

The bacterial metallome: composition and stability with specific reference to the anaerobic bacterium Desulfovibrio desulfuricans

  • Larry L. BartonAffiliated withDepartment of Biology, Laboratory of Microbial Chemistry, University of New Mexico Email author 
  • , Florence GoulhenAffiliated withInstitut de Biologie Structurale et Microbiologie, Unité de Bioénergétique et Ingénierie des Protéines, CNRS
  • , Mireille BruschiAffiliated withInstitut de Biologie Structurale et Microbiologie, Unité de Bioénergétique et Ingénierie des Protéines, CNRS
  • , Nicole A. WoodardsAffiliated withDepartment of Biology, Laboratory of Microbial Chemistry, University of New Mexico
  • , Richard M. PlunkettAffiliated withDepartment of Biology, Laboratory of Microbial Chemistry, University of New Mexico
  • , Frans J. M. RietmeijerAffiliated withDepartment of Earth and Planetary Sciences, University of New Mexico

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Abstract

In bacteria, the intracellular metal content or metallome reflects the metabolic requirements of the cell. When comparing the composition of metals in phytoplankton and bacteria that make up the macronutrients and the trace elements, we have determined that the content of trace elements in both of these microorganisms is markedly similar. The trace metals consisting of transition metals plus zinc are present in a stoichometric molar formula that we have calculated to be as follows: Fe1Mn0.3Zn0.26Cu0.03Co0.03Mo0.03. Under conditions of routine cultivation, trace metal homeostasis may be maintained by a series of transporter systems that are energized by the cell. In specific environments where heavy metals are present at toxic levels, some bacteria have developed a detoxification strategy where the metallic ion is reduced outside of the cell. The result of this extracellular metabolism is that the bacterial metallome specific for trace metals is not disrupted. One of the microorganisms that reduces toxic metals outside of the cell is the sulfate-reducing bacterium Desulfovibrio desulfuricans. While D. desulfuricans reduces metals by enzymatic processes involving polyhemic cytochromes c 3 and hydrogenases, which are all present inside the cell; we report the presence of chain B cytochrome c nitrite reductase, NrfA, in the outer membrane fraction of D. desulfuricans ATCC 27774 and discuss its activity as a metal reductase.

Keywords

Metallome Chromium Trace metals Transition metals