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A chemical and mineralogical investi...

MacLean, Lachlan Charles Wandlass.

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A chemical and mineralogical investigation into the role of Gram positive and Gram negative sulfate-reducing bacteria in iron sulfide formation.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	A chemical and mineralogical investigation into the role of Gram positive and Gram negative sulfate-reducing bacteria in iron sulfide formation./
作者:	MacLean, Lachlan Charles Wandlass.
面頁冊數:	151 p.
附註:	Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0886.
Contained By:	Dissertation Abstracts International69-02B.
標題:	Biogeochemistry. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NR36713
ISBN:	9780494367131

A chemical and mineralogical investigation into the role of Gram positive and Gram negative sulfate-reducing bacteria in iron sulfide formation.
MacLean, Lachlan Charles Wandlass.

A chemical and mineralogical investigation into the role of Gram positive and Gram negative sulfate-reducing bacteria in iron sulfide formation. - 151 p.

Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0886.

Thesis (Ph.D.)--The University of Western Ontario (Canada), 2007.

In vitro laboratory experiments were conducted to study the molecular interaction between biogenic FeS and the surfaces of two sulfate-reducing bacteria. Desulfovibrio desulfuricans and Desulfotomaculum ruminis each contain a different cell envelope (Gram negative vs. Gram positive, respectively). High-resolution transmission electron microscopy revealed that the nanophase FeS formed by D. ruminis was intimately associated with the bacterial cell surface and the aggregation of randomly oriented nanoparticles indicates the cell wall influences the nucleation and growth of these particles. Carbon near-edge X-ray absorption fine structure spectra confirmed that polysaccharides were involved in FeS mineral growth. In contrast, biogenic FeS formed by D. desulfuricans occurred as nanoparticles loosely associated with the Gram-negative cell wall, which allowed them to rotate freely and grow via oriented aggregation. The examination of a modern microbial system demonstrated bacterial cell walls and extracellular polymers influence the formation of metal sulfides. A biofilm sample, collected from an anaerobic borehole 1.474 km below land surface in the Evander gold mine, Republic of South Africa, possessed bacteria mineralized with fine-grain ZnS and FeS. Pyrite was observed throughout the biofilm in both framboidal (spherical aggregates of 0.5-1 mum FeS2 crystals) and euhedral (2-3 mum) mineral habits. 16S rDNA analysis revealed a mixed community of microorganisms dominated by sulfate reducing bacteria and methanogens, and minor sulfide and CH4 oxidizing chemolithotrophs. Focused-ion beam sectioning of framboids followed by carbon near-edge X-ray absorption fine structure measurements using both STXM and X-PEEM revealed that the pyrite crystals grew within an organic carbon matrix consisting of exopolysaccharides and possibly extracellular DNA, which is intuitively important in sulfide mineral diagenesis. The application of these high resolution surface sensitive methods to examine for bacteria-mineral interactions in fossilized sulfate reducing colonies found both chemical and mineralogical fingerprints that may be used in future studies to identify biomarkers, i.e. biogenicity, of Precambrian or extraterrestrial sulfides.

ISBN: 9780494367131Subjects--Topical Terms:

545717
Biogeochemistry.

A chemical and mineralogical investigation into the role of Gram positive and Gram negative sulfate-reducing bacteria in iron sulfide formation.
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520 $a In vitro laboratory experiments were conducted to study the molecular interaction between biogenic FeS and the surfaces of two sulfate-reducing bacteria. Desulfovibrio desulfuricans and Desulfotomaculum ruminis each contain a different cell envelope (Gram negative vs. Gram positive, respectively). High-resolution transmission electron microscopy revealed that the nanophase FeS formed by D. ruminis was intimately associated with the bacterial cell surface and the aggregation of randomly oriented nanoparticles indicates the cell wall influences the nucleation and growth of these particles. Carbon near-edge X-ray absorption fine structure spectra confirmed that polysaccharides were involved in FeS mineral growth. In contrast, biogenic FeS formed by D. desulfuricans occurred as nanoparticles loosely associated with the Gram-negative cell wall, which allowed them to rotate freely and grow via oriented aggregation. The examination of a modern microbial system demonstrated bacterial cell walls and extracellular polymers influence the formation of metal sulfides. A biofilm sample, collected from an anaerobic borehole 1.474 km below land surface in the Evander gold mine, Republic of South Africa, possessed bacteria mineralized with fine-grain ZnS and FeS. Pyrite was observed throughout the biofilm in both framboidal (spherical aggregates of 0.5-1 mum FeS2 crystals) and euhedral (2-3 mum) mineral habits. 16S rDNA analysis revealed a mixed community of microorganisms dominated by sulfate reducing bacteria and methanogens, and minor sulfide and CH4 oxidizing chemolithotrophs. Focused-ion beam sectioning of framboids followed by carbon near-edge X-ray absorption fine structure measurements using both STXM and X-PEEM revealed that the pyrite crystals grew within an organic carbon matrix consisting of exopolysaccharides and possibly extracellular DNA, which is intuitively important in sulfide mineral diagenesis. The application of these high resolution surface sensitive methods to examine for bacteria-mineral interactions in fossilized sulfate reducing colonies found both chemical and mineralogical fingerprints that may be used in future studies to identify biomarkers, i.e. biogenicity, of Precambrian or extraterrestrial sulfides.
520 $a Keywords. nanocrystalline FeS, sulfate-reducing bacteria, near-edge X-ray absorption fine structure, extended X-ray absorption fine structure, scanning transmission X-ray microscopy, framboid, high-resolution transmission electron microscopy, microfossil.
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