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Microbial reduction of Fe(III) in the presence of oxygen under low pH conditions
Author(s) -
Küsel Kirsten,
Roth Ursula,
Drake Harold L.
Publication year - 2002
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1046/j.1462-2920.2002.00314.x
Subject(s) - anoxic waters , microcosm , incubation , sediment , environmental chemistry , biology , anaerobic exercise , oxygen , nuclear chemistry , chemistry , biochemistry , physiology , paleontology , organic chemistry
Summary In acidic, coal mining lake sediments, facultatively anaerobic Acidiphilium species are probably involved in the reduction of Fe(III). Previous results indicate that these bacteria can co‐respire O 2 and Fe(III). In this study, we investigated the capacity of the sediment microbiota to reduce Fe(III) in the presence of O 2 at pH 3. In sediment microcosms with 4% O 2 in the headspace, the concentration of Fe(II) increased at a rate of 1.03 μmol (g wet sediment) − 1 day − 1 within the first 7 days of incubation which was similar to the rate obtained with controls incubated under anoxic conditions. However, in microcosms incubated under air, Fe(II) was consumed after a lag phase of 8 h with a rate of 2.66 μmol (g wet sediment) − 1 day − 1 . Acidiphilium cryptum JF‐5, isolated from this sediment, reduced soluble Fe(III) with either 4 or 21% O 2 in the headspace, and concomitantly consumed O 2 . However, the rate of Fe(II) formation normalized for cell density decreased under oxic conditions. Schwertmannite, the predominant Fe(III)‐mineral of this sediment, was also reduced by A. cryptum JF‐5 under oxic conditions. The rate of Fe(II) formation by A. cryptum JF‐5 decreased after transfer from preincubation under air in medium lacking Fe(III). Acidiphilium cryptum JF‐5 did not form Fe(II) when preincubated under air and transferred to anoxic medium containing Fe(III) and chloramphenicol, an inhibitor of protein synthesis. These results indicate that: (i) the reduction of Fe(III) can occur at low O 2 concentrations in acidic sediments; (ii) Fe(II) can be oxidized at O 2 concentrations near saturation; and (iii) the enzyme(s) responsible for the reduction of Fe(III) in A. cryptum JF‐5 are not constitutive.