Abstract
Nine out of ten anaerobic enrichment cultures inoculated with sediment samples from various freshwater, brackish-water, and marine sediments exhibited ferrous iron oxidation in mineral media with nitrate and an organic cosubstrate at pH 7.2 and 30° C. Anaerobic nitrate-dependent ferrous iron oxidation was a biological process. One strain isolated from brackish-water sediment (strain HidR2, a motile, nonsporeforming, gram-negative rod) was chosen for further investigation of ferrous iron oxidation in the presence of acetate as cosubstrate. Strain HidR2 oxidized between 0.7 and 4.9 mM ferrous iron aerobically and anaerobically at pH 7.2 and 30° C in the presence of small amounts of acetate (between 0.2 and 1.1 mM). The strain gained energy for growth from anaerobic ferrous iron oxidation with nitrate, and the ratio of iron oxidized to acetate provided was constant at limiting acetate supply. The ability to oxidize ferrous iron anaerobically with nitrate at approximately pH 7 appears to be a widespread capacity among mesophilic denitrifying bacteria. Since nitrate-dependent iron oxidation closes the iron cycle within the anoxic zone of sediments and aerobic iron oxidation enhances the reoxidation of ferrous to ferric iron in the oxic zone, both processes increase the importance of iron as a transient electron carrier in the turnover of organic matter in natural sediments.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Received: 24 April 1997 / Accepted: 22 September 1997
Rights and permissions
About this article
Cite this article
Benz, M., Brune, A. & Schink, B. Anaerobic and aerobic oxidation of ferrous iron at neutral pH by chemoheterotrophic nitrate-reducing bacteria. Arch Microbiol 169, 159–165 (1998). https://doi.org/10.1007/s002030050555
Issue Date:
DOI: https://doi.org/10.1007/s002030050555