Daâd A. Saffarini Associate Professor 1979: B.S. Biology Department University of Jordan Amman/Jordan 1988: Ph.D. Dept. Biological Sciences University of Wisconsin-Milwaukee 1989-1992: Postdoctoral Research Fellow Center for Great Lakes Studies University of Wisconsin-Milwaukee	Office: Lapham N309 Phone: 414-229-2964 FAX: 414-229-3926 Email: daads@uwm.edu Electronic Reserve Materials:
Environmental and Molecular Microbiology

Research Interests

Iron and manganese are abundant transition metals that are used by bacteria as terminal electron acceptors (in place of oxygen) during anaerobic respiration. This respiratory process impacts both the carbon and metal cycles in aquatic environments. Cycling of these metals provides bacteria with a continuous source of electron acceptors for the oxidation of organic carbon. Furthermore, many of the bacteria that are able to use metals for respiration are also able to degrade several pollutants, which makes these microorganisms useful tools for bioremediation. Shewanella putrefaciens is a metal reducer that can use more than ten different electron acceptors under anaerobic conditions. These include solid metal oxides and soluble electron acceptors such as nitrate and fumarate. The diversity of electron acceptors S. putrefaciens can use, makes it an ideal model organism for studying the molecular mechanisms of anaerobic respiration. Our research is directed towards understanding the regulation of anaerobic respiration in metal reducing bacteria with special attention to the molecular mechanisms of iron and manganese reduction. We are using genetic and molecular biology techniques to identify and characterize the iron and manganese reductases. Some of the proteins involved in metal reduction are localized to the outer membrane of S. putrefaciens. To our knowledge, this is the first example of a respiratory system where the components are found on the outer membrane and not the inner membrane of bacterial cells. Another related area that we are investigating involves the elucidation of the regulatory mechanisms of anaerobic respiration in environmental isolates capable of utilizing a large number of electron acceptors including solid metal oxides.

Selected Publications

Saffarini, D. R. Schultz and A. Beliaev. 2003. Involvement of cyclic AMP (cAMP) and CAMP receptor protein in anaerobic respiration of Shewanella oneidensis. J. Bacteriol. 185:3668-3671. http://jb.asm.org/cgi/reprint/185/12/3668.pdf Saffarini, D., S. Blumerman, and K. Mansoorabadi. 2002. Role of menaquinones in Fe(III) reduction by membrane fractions of Shewanella putrefaciens. J. Bacteriol. 184:846-848. http://jb.asm.org/cgi/reprint/184/3/846.pdf Beliaev, A., Saffarini, D., McLaughlin, J. and Hunnicutt, D. 2001. MtrC, an outer membrane decaheme c cytochrome required for metal reduction in Shewanella putrefaciens MR-1. Molecular Microbiology. 39:722-730. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db= PubMed&dopt=Citation&list_uids=11169112 Venkateswaran, K., Moser, D.P., Dollhopf, M.E., Lies, D.P., Saffarini, D.A., MacGregor, B.J., Ringelberg, D.B., White, D.C., Nishijima, M., Sano, H., Burghardt, J. Stackebrandt, E. and Nealson, K.H. 1999. Polyphasic taxonomy of the genus Shewanella and description of Shewanella oneidensis sp. nov. Int. J. Syst. Bacteriol. 49: 705-724. http://www.ncbi.nlm.nih.gov:80/entrez/ query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10319494&dopt=Abstract Beliaev, A. and D. Saffarini. 1998. Shewanella putrefaciens mtrB encodes an outer membrane protein required for Fe(III) and Mn(IV) reduction. J. Bacteriol. 181:6292-6297. http://jb.asm.org/cgi/reprint/180/23/6292.pdf Lovley, D., J. Coates, D. Saffarini and D. Lonergan. 1997. Dissimilatory Iron Reduction. In:, G. Winkelmann and C. Carrano (Eds), Transition metals in microbial metabolism. pp 187-215. Nealson, K.H., D. Moser and D. Saffarini. 1995. Anaerobic electron acceptor chemotaxis in Shewanella putrefaciens: . Applied and Environmental Microbiology. 61:1551-1554. Saffarini, D., T. DiChristina, D. Bermudes and K. Nealson. 1994. Anaerobic respiration of Shewanella putrefaciens requires both chromosomal and plasmid-borne genes. FEMS Microbiol. Lett. 119:271-278. Nealson, K. and D. Saffarini. 1994. Iron and manganese in anaerobic respiration: Environmental significance, physiology and regulation. Ann. Rev. Microbiol.48:311-343. Nealson, K., D. Saffarini, D. Moser and M.J. Smith. 1994. A method for monitoring tactic responses of bacteria under anaerobic conditions. J. Microbiological Methods. 20:211-218. Nealson, K., Saffarini, D., Lukiewicz, S. 1994. Bacterial mutant strains unable to reduce nitroxides. Current Topics in Biophysics 18:39-45. Saffarini, D.A. and K.H. Nealson. 1993. Sequence and genetic characterization of etrA, an fnr analog that regulates anaerobic respiration in Shewanella putrefaciens MR-1. J. Bacteriol. 175:7938-7944.