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Appl. Environ. Microbiol., Nov 1996, 4044-4048, Vol 62, No. 11
X Hu and GL Boyer
The bacterium Bacillus megaterium ATCC 19213 is known to produce two
hydroxamate siderophores, schizokinen and N-deoxyschizokinen, under
iron-limited conditions. In addition to their high affinity for ferric
ions, these siderophores chelate aluminum. Aluminum was absorbed by B.
megaterium ATCC 19213 through the siderophore transport receptor, providing
an extra pathway for aluminum accumulation into iron-deficient bacteria. At
low concentrations of the metal, siderophore-mediated uptake was the
dominant process for aluminum accumulation. At high concentrations of
aluminum, passive transport dominated and siderophore production slowed the
passive transport of aluminum into the cell. Siderophore production was
affected by the aluminum content in the media. High concentrations of
aluminum increased production of siderophores in iron-limited cultures, and
this production continued into stationary phase. Aluminum did not stimulate
siderophore production in iron-replete cultures. The production of
siderophores markedly affected aluminum uptake. This has direct
implications on the toxicity of heavy metals under iron-deficient
conditions.
Copyright © 1996, American Society for Microbiology
Siderophore-Mediated Aluminum Uptake by Bacillus megaterium ATCC 19213
Department of Chemistry, State University of New York, College of Environmental Science and Forestry, Syracuse, New York 13210
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