HR: 10:20h
AN: B22D-01 INVITED    [Abstracts]
TI: The Diverse Microbiology of Anaerobic Fe(II) Oxidation
AU: * Coates, J D
EM: jcoates@nature.berkeley.edu
AF: UC Berkeley, 271 Koshland Hall Dept of Plant and Microbial Biology, Berkeley, CA 94720, United States
AU: Weber, K A
EM: kweber@nature.berkeley.edu
AF: UC Berkeley, 271 Koshland Hall Dept of Plant and Microbial Biology, Berkeley, CA 94720, United States
AU: Scherer, M
EM: michelle-scherer@uiowa.edu
AF: University of Iowa, Civil and Environmental Engineering, Iowa City, IA 52242, United States
AU: Achenbach, L A
EM: laurie@micro.siu.edu
AF: Southern Illinois University, Dept of Microbiology, Carbondale, IL 62901, United States
AB: Although anaerobic microbial oxidation of Fe(II) has been know for over a decade there is still a paucity of information available on this important metabolic process or the organisms involved. Recent studies have indicated that the metabolism is ubiquitous and a broad diversity of organisms are capable of oxidizing Fe(II) in the absence of oxygen. Our previous studies demonstrated the existence of geochemical conditions conducive to supporting the activity of nitrate-dependent Fe(II) oxidizing bacteria (NFoB) in sedimentary environments. As part of these studies we isolated and characterized several novel NFoBs. Three of these organisms, Diaphorobacter sp. strain TPSY, Ferrutens nitratireducens strain 2002 and Azospira suillum strain PS are currently undergoing whole genome shotgun sequencing in an effort to gain insight into the biochemistry and molecular biology of this geochemically important metabolism. These organisms represent diverse genera capable of anaerobically oxidizing Fe(II) using nitrate as the electron acceptor. Two of these organisms, strain 2002 and strain TPSY, are also capable of the anaerobic nitrate-dependent oxidation of U(IV) to U(VI). Diaphorobacter sp. strain TPSY was isolated from uranium and nitrate contaminated groundwater and is a member of the Comamonadaceae family in the beta subclass of the Proteobacteria, closely related to Diaphorobacter nitroreducens. It represents the first example of an anaerobic Fe(II)-oxidizer from the Comamonadaceae family and grows mixotrophically requiring an organic carbon source when growing with Fe(II) and nitrate as the electron donor and acceptor respectively. F. nitratireducens strain 2002 was isolated from aquatic sediment and is the type strain of a new genus, Ferrutens, in the beta class of the Proteobacteria. Its closest relative is Chromobacterium violaceum, a common soil bacterium. In contrast to C. violaceum, F. nitratireducens is non-fermentative and does not produce free cyanide (CN-) or the purple/violet pigments indicative of violacein production, a characteristic of Chromobacterium species. F. nitratireducens strain 2002 is currently the only described mesophilic autotrophic nitrate-dependent Fe(II)-oxidizing organism and biogenically produces green rust as a primary end-product of this metabolism. Azospira suillum strain PS is a member of the beta subclass of the Proteobacteria and was isolated based on its ability to grow anaerobically by dissimilatory perchlorate reduction from animal waste lagoons. It represents one of the dominant perchlorate-reducing genera in the natural environment. Although this organism does not grow by Fe(II) oxidation, phenotypic studies revealed its ability to couple Fe(II) oxidation to nitrate reduction and it was the first organism shown to be capable of the oxidation of the Fe(II) content of silicaceous Fe(II) minerals including almandine and staurolite. It was also the first organism shown to be capable of biogenic magnetite production through anaerobic Fe(II) oxidative processes. These varied organisms demonstrate both the phylogenetic and metabolic diversity of organisms involved in the anaerobic bio-oxidation of Fe(II) and raise many questions regarding the underlying mechanisms involved in this important metabolism in the natural environment.
DE: 0400 BIOGEOSCIENCES
DE: 0404 Anoxic and hypoxic environments (4802, 4834)
DE: 0412 Biogeochemical kinetics and reaction modeling (0414, 0793, 1615, 4805, 4912)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0418 Bioremediation
SC: Biogeosciences [B]
MN: 2007 Fall Meeting