Email updates

Keep up to date with the latest news and content from BMC Microbiology and BioMed Central.

Open Access Highly Accessed Research article

The genome sequence of Geobacter metallireducens: features of metabolism, physiology and regulation common and dissimilar to Geobacter sulfurreducens

Muktak Aklujkar1*, Julia Krushkal2, Genevieve DiBartolo3, Alla Lapidus3, Miriam L Land4 and Derek R Lovley1

Author Affiliations

1 Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, USA

2 Department of Preventive Medicine and Center of Genomics and Bioinformatics, University of Tennessee Health Science Center, University of Tennessee, Memphis, TN, USA

3 Department of Energy, Joint Genome Institute, Walnut Creek, CA, USA

4 Oak Ridge National Laboratory, Oak Ridge, TN, USA

For all author emails, please log on.

BMC Microbiology 2009, 9:109  doi:10.1186/1471-2180-9-109

Published: 27 May 2009

Abstract

Background

The genome sequence of Geobacter metallireducens is the second to be completed from the metal-respiring genus Geobacter, and is compared in this report to that of Geobacter sulfurreducens in order to understand their metabolic, physiological and regulatory similarities and differences.

Results

The experimentally observed greater metabolic versatility of G. metallireducens versus G. sulfurreducens is borne out by the presence of more numerous genes for metabolism of organic acids including acetate, propionate, and pyruvate. Although G. metallireducens lacks a dicarboxylic acid transporter, it has acquired a second putative succinate dehydrogenase/fumarate reductase complex, suggesting that respiration of fumarate was important until recently in its evolutionary history. Vestiges of the molybdate (ModE) regulon of G. sulfurreducens can be detected in G. metallireducens, which has lost the global regulatory protein ModE but retained some putative ModE-binding sites and multiplied certain genes of molybdenum cofactor biosynthesis. Several enzymes of amino acid metabolism are of different origin in the two species, but significant patterns of gene organization are conserved. Whereas most Geobacteraceae are predicted to obtain biosynthetic reducing equivalents from electron transfer pathways via a ferredoxin oxidoreductase, G. metallireducens can derive them from the oxidative pentose phosphate pathway. In addition to the evidence of greater metabolic versatility, the G. metallireducens genome is also remarkable for the abundance of multicopy nucleotide sequences found in intergenic regions and even within genes.

Conclusion

The genomic evidence suggests that metabolism, physiology and regulation of gene expression in G. metallireducens may be dramatically different from other Geobacteraceae.