This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Caiazza, N. C.
Right arrow Articles by Newman, D. K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Caiazza, N. C.
Right arrow Articles by Newman, D. K.
Agricola
Right arrow Articles by Caiazza, N. C.
Right arrow Articles by Newman, D. K.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, October 2007, p. 6150-6158, Vol. 73, No. 19
0099-2240/07/$08.00+0     doi:10.1128/AEM.02830-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Phototrophic Fe(II) Oxidation Promotes Organic Carbon Acquisition by Rhodobacter capsulatus SB1003{triangledown}

Nicky C. Caiazza,1,3 Douglas P. Lies,1,3 and Dianne K. Newman1,2,3*

Division of Geological and Planetary Sciences,1 Division of Biology,2 Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 911253

Received 5 December 2006/ Accepted 1 August 2007

Anoxygenic phototrophic Fe(II) oxidation is usually considered to be a lithoautotrophic metabolism that contributes to primary production in Fe-based ecosystems. In this study, we employed Rhodobacter capsulatus SB1003 as a model organism to test the hypothesis that phototrophic Fe(II) oxidation can be coupled to organic carbon acquisition. R. capsulatus SB1003 oxidized Fe(II) under anoxic conditions in a light-dependent manner, but it failed to grow lithoautotrophically on soluble Fe(II). When the strain was provided with Fe(II)-citrate, however, growth was observed that was dependent upon microbially catalyzed Fe(II) oxidation, resulting in the formation of Fe(III)-citrate. Subsequent photochemical breakdown of Fe(III)-citrate yielded acetoacetic acid that supported growth in the light but not the dark. The deletion of genes (RRC00247 and RRC00248) that encode homologs of atoA and atoD, required for acetoacetic acid utilization, severely impaired the ability of R. capsulatus SB1003 to grow on Fe(II)-citrate. The growth yield achieved by R. capsulatus SB1003 in the presence of citrate cannot be explained by lithoautotrophic growth on Fe(II) enabled by indirect effects of the ligand [such as altering the thermodynamics of Fe(II) oxidation or preventing cell encrustation]. Together, these results demonstrate that R. capsulatus SB1003 grows photoheterotrophically on Fe(II)-citrate. Nitrilotriacetic acid also supported light-dependent growth on Fe(II), suggesting that Fe(II) oxidation may be a general mechanism whereby some Fe(II)-oxidizing bacteria mine otherwise inaccessible organic carbon sources.

* Corresponding author. Present address: Department of Biology, MIT, 77 Massachussetts Ave., 68-380, Cambridge, MA 02139. Phone: (617) 324-2770. Fax: (617) 324-3972. E-mail: dkn{at}mit.edu

{triangledown} Published ahead of print on 10 August 2007.

Applied and Environmental Microbiology, October 2007, p. 6150-6158, Vol. 73, No. 19
0099-2240/07/$08.00+0     doi:10.1128/AEM.02830-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.





Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»