DOE Human Genome Program Contractor-Grantee Workshop VIII
February 27-March 2, 2000  Santa Fe, NM

117. The Genome of Geobacter sulfurreducens

B.A. Methe¹, L. Banerjei², W.C. Nierman², O. Snoeyenbos-West¹, S. Sciufo¹, and D.E. Lovley¹

¹University of Massachusetts, Amherst, MA 01003 and ²The Institute for Genome Research, Rockville, MD 20850

bmethe@microbio.umass.edu

The complete genome sequence of Geobacter sulfurreducens is currently being determined to better understand its genetic potential. G. sulfurreducens is an important member of a family (Geobacteraceae) of delta Proteobacteria capable of oxidizing organic compounds including aromatic hydrocarbons to carbon dioxide with Fe(III) or other metals and metalloids including U(VI), Tc(VII), Co(III), Cr(IV), Au(III), Hg(II), As(V) and Se(VII) serving as the terminal electron acceptor. It is the dominant group of iron reducing microorganisms recovered from a wide variety of aquifer and subsurface environments when both molecular and traditional culturing techniques are used. Geobacter plays a critical role in the biogeochemical cycling of carbon, iron and other metals. Its genetics and physiology are a subject of intense study in part due to the importance that these processes can play in the remediation of contaminated anaerobic subsurface environments. The determination of the G. sulfurreducens genome is being accomplished using a random shotgun cloning approach to provide at least six-fold coverage of a 1mb genome followed by closure of remaining physical or sequence gaps. TIGR Assembler software and other computer programs developed by The Institute for Genome Research are used to assemble the genome and aid in gap closing, finishing and annotation. Searches of sequences and contigs from the early random phase of sequencing using the BLAST algorithm and database have produced high scores with low expect values indicating significant homologies to proteins contained in the database. These include enzymes considered important to basic housekeeping functions such as tRNA synthases and amino acid synthesis as well as those essential to other metabolic processes known to occur in G. sulfurreducens including nitrogen fixation. A number of sequences have produced no significant alignments indicating the likelihood of genes encoding for novel functions. Of further significance has been the extension of N-terminal sequences previously obtained from cytochromes known to be important in dissimilatory iron reduction. Thus, the genome will provide information crucial to the further understanding of this important metabolic process.