Iron microbial oxidation

Organic Carbon Oxidation Microbially Coupled to Reduction of Fe(III)(hydr)oxide. More and more evidence is accumulating that bacteria can grow anaerobically by coupling organic carbon oxidation to the dissimilatory reduction of iron(III) oxides (Nealson, 1982 Arnold et al., 1986 Lovely and Philips, 1988 Nealson and Myers, 1990). 

Filer JM, Mojzsis SJ, Arrhenius G (1997) Carbon isotope evidence for early life discussion. Nature 386 665 Emerson D (2000) Microbial oxidation of Ee(II) and Mn(II) at circumneutral pH. In Environmental metal-microbe interactions. Lovley DR (ed) ASM Press, Washington DC, p 31-52 Ewers WE (1983) Chemical factors in the deposition and diagenesis of banded iron-formation. In Iron formations facts and problems. Trendall AF, Morris RC (eds) Elsevier, Amsterdam, p 491-512 Farley KJ, Dzombak DA, Morel FMM (1985) A surface precipitation model for the sorption of cations on metal oxides. J Colloid Interface Sci 106 226-242... 

Roden EE, Zachara JM (1996) Microbial reduction of crystalline iron(III) oxides influence of oxide surface area and potential for cell growth. Environ Sci Technol 30 1618-1628 Roden EE, Urrutia MM (2002) Influence of biogenic Fe(II) on bacterial reduction of crystalline Fe(lll) oxides. Geomicrobio J 19 209-251... 

Straub KL, Benz M, Schink B, Widdel F (1996) Anaerobic, nitrate-dependent microbial oxidation of ferrous iron. App Environ Microbio 62 1458-1460... 

Ullmanrf s Encyclopedia of Technical Chemistry (1992) Vol. 18,VCH, Weinheim Urmtia, M.M. Roden, E.E. Zachara, J.M. (1999) Influence of aqueous and solid-phase Fe(II) complexants on microbial reduction of crystalline iron(III) oxides. Environ. Sci. Techn. 33 4022-4028... 

All measured profiles of sulfate reduction in sediments indicate that much sulfide production and, by inference, oxidation occurs in permanently anaerobic sediments (78, 73, 90,101). The two most likely electron acceptors for anaerobic sulfide oxidation are manganese and iron oxides. Burdige and Nealson (151) demonstrated rapid chemical as well as microbially catalyzed oxidation of sulfide by crystalline manganese oxide (8-Mn02), although elemental S was the inferred end product. Aller and Rude (146) documented microbial oxidation of sulfide to sulfate accompanied by reductive dissolution... 

Beyer et al. (49) found that, during microbial desulfurization, pyritic sulfur decreases and elemental sulfur increases with time, whereas the organic sulfur remains unchanged. They suggested that microbial oxidation of pyrite produces ferric sulfate [Fe2(S04)3] and that the simultaneous inorganic reaction of ferric iron with pyrite produces elemental sulfur and ferrous iron, as follows ... 

About 35% of the iron and 75% of the manganese in soils and sediments is in the form of free oxides (Canfield, 1997 Cornell and Schwertmann, 1996 Thamdrup, 2000). The remainder occurs as a minor constituent of silicate minerals. The lattice stmcture of Fe(III) oxide minerals varies widely. Freshly oxidized Fe(III) precipitates rapidly as ferrihydrite (Fe(OH)3), a reddish-brown, amorphous, poorly crystalline mineral. Ferrihydrite is the dominant product of Fe(II) oxidation whether it occurs by abiotic oxidation, aerobic microbial oxidation, or anaerobic microbial oxidation (Straub et al., 1998). Over a period of weeks to months, amorphous ferrihydrite crystals undergo diagenesis to yield well-ordered, strongly crystalline, stable minerals such as hematite(a-Fe203) and goethite (a-FeOOH) (Cornell and Schwertmann, 1996). 

The pre-1991 research involving microbial oxidation of 29 sulfide minerals of iron, copper, arsenic, antimony, gallium, zinc, lead, nickel, and mercury was compiled by Nordstrom and Southam (1997). The importance of microbially mediated sulfide oxidation has been recognized for several decades (Nordstrom and Southam, 1997). Bacteria catalyze the oxidative dissolution of sulfide minerals, increasing the production of acidity in mine wastes. In the absence of bacteria, the rate of sulfide oxidation stabilizes as the pH decreases below 3.5 (Singer and Stumm, 1970). 

However, the mechanism for direct oxidation is poorly understood (Silverman and Ehrlich, 1964). Iron is also made available for microbial oxidation after dissociation of the sulfide complexes by a chemical oxidation of the sulfide moiety of the mineral. A strong chemical oxidizing agent is the Fe ion itself. Singer eind Stumm (1970) showed that, under acidic conditions and in the absence of bacteria, Fe was a much more effective catalyst of pyrite oxidation than was ferrous iron. However, in the presence of bacteria, the rate of pyrite oxidation in the presence of Fe was higher the reduced iron was biologically oxidized to ferric iron which then oxidized the pyrite ... 

MICROBIAL OXIDATION AND REDUCTION OF IRON IN THE ROOT ZONE AND INFLUENCES ON METAL MOBILITY... 

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