Chemical and Biological Interactions during Nitrate and Goethite Reduction by Shewanella putrefaciens 200

Abstract

Although previous research has demonstrated that NO 3 ؊ inhibits microbial Fe(III) reduction in laboratory cultures and natural sediments, the mechanisms of this inhibition have not been fully studied in an environmentally relevant medium that utilizes solid-phase, iron oxide minerals as a Fe (III)

Inhibition of NO 3 − and NO 2 − Reduction by Microbial Fe(III) Reduction: Evidence of a Reaction between NO 2 − and Cell Surface-Bound Fe 2+

“…Although the general methodology employed in the Fe(III) and NO 3 Ϫ reduction experiments has been previously described (6), a summary of the procedure is presented here. All experiments were conducted in 150-ml serum bottles, crimp sealed with butyl rubber stoppers under a 95% N 2 -5% H 2 headspace.…”

“…Samples for NO 3 Ϫ and NO 2 Ϫ analyses were diluted twofold in Milli-Q water, frozen, and stored for later analysis by ion chromatography as previously described (6). NH 4 ϩ was quantified in some experiments using the colorimetric phenate method (15).…”

“…NH 4 ϩ was quantified in some experiments using the colorimetric phenate method (15). N 2 O production was quantified by removing 25.0 l of headspace gas from the batch reactors using a gas-tight syringe and analyzed via gas chromatography as previously described (6).…”

“…NO x Ϫ reduction by microorganisms typically precedes ferric (hydr)oxide reduction in experimental or subsurface systems, in part because NO x Ϫ tends to be more available to cells than the highly insoluble (at neutral pH) forms of Fe(III) (1,9,29,30,39). Recently, though, Cooper et al reported that the reduction of NO 3 Ϫ and NO 2 Ϫ by S. putrefaciens 200 was inhibited by the presence of the solid-phase ferric (hydr)oxide goethite (␣-FeOOH) (6). In addition, they observed that the presence of goethite in NO x Ϫ -reducing incubations resulted in greatly enhanced production of N 2 O. Cooper et al speculated that the inhibition and enhanced N 2 O production resulted from reaction of small amounts of biogenic Fe(II) with NO 2 Ϫ to form an Fe (hydr)oxide coating on the cell surface that inhibited transport of soluble electron acceptors into the cell.…”

Fine structure characterization of zero-valent iron nanoparticles for decontamination of nitrites and nitrates in wastewater and groundwater

“…Recently, to ensure safe drinking water quality in Taiwan, the regulatory standards of nitrite and nitrate were being set up at 0.1 and 10 mg l −1 , respectively [4]. The removal of nitrite and nitrate from contaminated wastewater frequently involves microbial nitrification/denitrification, ion exchange, reverse osmosis, electrocatalytic, and high temperature and chemical reduction process [5][6][7][8][9][10]. Microbial reactions are inefficient due to generally slow process and required intensive maintenance, including the constant supply of organic substances as electron donors.…”