Details

Autor(en) / Beteiligte

• Kato, Shingo
• Ohkuma, Moriya
• Gralnick, Jeffrey A
• Gralnick, Jeffrey A.

Titel

A Single Bacterium Capable of Oxidation and Reduction of Iron at Circumneutral pH

Ist Teil von

• Microbiology spectrum, 2021-09, Vol.9 (1), p.e0016121-e0016121

Ort / Verlag

United States: American Society for Microbiology

Erscheinungsjahr

2021

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• Fe(II)-oxidizing microorganisms and Fe(III)-reducing microorganisms, which drive the biogeochemical Fe cycle on the Earth's surface, are phylogenetically and ecologically diverse. However, no single organism capable of aerobic Fe(II) oxidation and anaerobic Fe(III) reduction at circumneutral pH have been reported so far. Here, we report a novel neutrophilic Fe(II)-oxidizing bacterium, strain MIZ03, isolated from an iron-rich wetland in Japan. Our cultivation experiments demonstrate that MIZ03 represents a much more versatile metabolism for energy acquisition than previously recognized in the genus . MIZ03 can grow chemolithoautotrophically at circumneutral pH by oxidation of Fe(II), H , or thiosulfate as the sole electron donor under (micro)aerobic conditions (i.e., using O as the sole electron acceptor). In addition, it can reduce Fe(III) or nitrate under anaerobic conditions. Thus, this is the first report demonstrating the presence of a single bacterium capable of both Fe(II) oxidation and Fe(III) reduction at circumneutral pH. The observed physiology was consistent with its 4.9-Mbp complete genome encoding key genes for iron oxidation/reduction ( and ), for nitrate reduction ( ), for thiosulfate oxidation ( ), and for carbon fixation via the Calvin cycle. Our metagenomic survey suggests that there are more members capable of Fe(II) oxidation and Fe(III) reduction. Such bifunctional may have an ecological advantage in suboxic/anoxic environments at circumneutral pH by recycling of Fe as the electron donor and acceptor. The biogeochemical cycle of iron (Fe) via reactions of oxidation, reduction, precipitation, and dissolution is involved in the cycle of other ecologically relevant elements, such as C, N, P, S, As, Co, Ni, and Pb. The Fe cycle on the Earth's surface is driven by a variety of Fe(II)-oxidizing microorganisms and Fe(III)-reducing microorganisms. Here, we discovered a novel bacterium, sp. strain MIZ03, capable of both Fe(II) oxidation and Fe(III) reduction at circumneutral pH, and we report its physiological characteristics and complete genome sequence. The unexpected capability of this bacterium provides novel insights into the Fe cycle in the environment. Moreover, this bacterium will help to better understand the molecular mechanisms of microbial Fe redox cycling as a model organism.