Journal Article

Alkaline Fe(III) reduction by a novel alkali-tolerant <i>Serratia</i> sp. isolated from surface sediments close to Sellafield nuclear facility, UK

Clare L. Thorpe, Katherine Morris, Christopher Boothman and Jonathan R. Lloyd

in FEMS Microbiology Letters

Volume 327, issue 2, pages 87-92
Published in print February 2012 |
Published online January 2012 | e-ISSN: 1574-6968 | DOI: http://dx.doi.org/10.1111/j.1574-6968.2011.02455.x

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Abstract

Extensive denitrification resulted in a dramatic increase in pH (from 6.8 to 9.5) in nitrate-impacted, acetate-amended sediment microcosms containing sediment representative of the Sellafield nuclear facility, UK. Denitrification was followed by Fe (III) reduction, indicating the presence of alkali-tolerant, metal-reducing bacteria. A close relative (99% 16S rRNA gene sequence homology) to Serratia liquefaciens dominated progressive enrichment cultures containing Fe (III)-citrate as the sole electron acceptor at pH 9 and was isolated aerobically using solid media. The optimum growth conditions for this facultatively anaerobic Serratia species were investigated, and it was capable of metabolizing a wide range of electron acceptors including oxygen, nitrate, FeGel, Fe -NTA and Fe-citrate and electron donors including acetate, lactate, formate, ethanol, glucose, glycerol and yeast extract at an optimum pH of c. 6.5 at 20 °C. The alkali tolerance of this strain extends the pH range of highly adaptable Fe (III)-reducing Serratia species from mildly acidic pH values associated with acid mine drainage conditions to alkali conditions representative of subsurface sediments stimulated for extensive denitrification and metal reduction.

Keywords: bioreduction; nitrate; bioremediation; iron reduction

Journal Article.  2947 words.  Illustrated.

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