Hexagonal Platelet-like Magnetite as a Biosignature of Thermophilic Iron-Reducing Bacteria and Its Applications to the Exploration of the Modern Deep, Hot Biosphere and the Emergence of Iron-Reducing Bacteria in Early Precambrian Oceans.

Hexagonal Platelet-like Magnetite as a Biosignature of Thermophilic Iron-Reducing Bacteria and Its Applications to the Exploration of the Modern Deep, Hot Biosphere and the Emergence of Iron-Reducing Bacteria in Early Precambrian Oceans.

MedLine Citation:	PMID: 23145573 Owner: NLM Status: Publisher
Abstract/OtherAbstract:	Abstract Dissimilatory iron-reducing bacteria are able to enzymatically reduce ferric iron and couple to the oxidation of organic carbon. This mechanism induces the mineralization of fine magnetite crystals characterized by a wide distribution in size and irregular morphologies that are indistinguishable from authigenic magnetite. Thermoanaerobacter are thermophilic iron-reducing bacteria that predominantly inhabit terrestrial hot springs or deep crusts and have the capacity to transform amorphous ferric iron into magnetite with a size up to 120 nm. In this study, I first characterize the formation of hexagonal platelet-like magnetite of a few hundred nanometers in cultures of Thermoanaerobacter spp. strain TOR39. Biogenic magnetite with such large crystal sizes and unique morphology has never been observed in abiotic or biotic processes and thus can be considered as a potential biosignature for thermophilic iron-reducing bacteria. The unique crystallographic features and strong ferrimagnetic properties of these crystals allow easy and rapid screening for the previous presence of iron-reducing bacteria in deep terrestrial crustal samples that are unsuitable for biological detection methods and, also, the search for biogenic magnetite in banded iron formations that deposited only in the first 2 billion years of Earth with evidence of life. Key Words: Biosignatures-Magnetite-Iron-reducing bacteria-Deep subsurface biosphere-Banded iron formation. Astrobiology 12, xxx-xxx.

Authors:	Yi-Liang Li
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Publication Detail:	Type: JOURNAL ARTICLE Date: 2012-11-12
Journal Detail:	Title: Astrobiology Volume: - ISSN: 1557-8070 ISO Abbreviation: Astrobiology Publication Date: 2012 Nov
Date Detail:	Created Date: 2012-11-13 Completed Date: - Revised Date: -
Medline Journal Info:	Nlm Unique ID: 101088083 Medline TA: Astrobiology Country: -
Other Details:	Languages: ENG Pagination: - Citation Subset: -
Affiliation:	Department of Earth Sciences, The University of Hong Kong , Hong Kong .
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