Microbial Effects in Promoting the Smectite to Illite Reaction: Role of Organic Matter Intercalated in the Interlayer

Abstract

Cysteine and toluene as model organic molecules were intercalated into Fe-rich smectite (nontronile, NAu-2). The illitization of these intercalated smectites as induced by microbial reduction of structural Fe(3+) was investigated. Iron-reducing bacterium Shewanella putrefaciens CN32 was incubated with lactate as the sole electron donor and structural Fe(3+) in cysteine- and toluene-intercalated NAu-2 (referred to as cysteine-NAu-2 and toluene-NAu-2 hereafter) as the sole electron acceptor. Anthraquinone- 2, 6-disulfonate (AQDS) was used as an electron shuttle in bicarbonate buffer. The extent of Fe(3+) reduction in cysteine-NAu-2 and toluene-NAu-2 was 15.7 and 5.4%, respectively, compared to 20.5% in NAu-2 without organic matter intercalation. In the bioreduced NAu-2, X-ray diffraction, and scanning and transmission electron microscopy did not detect any discrete illite, although illite/ smectite mixed layer or high charge smectite phases were observed. In bioreduced cysteine-NAu-2, discrete illite and siderite formed. In contrast, bioreduction of toluene-NAu-2 did not result in any mineralogical changes. The contrasting bioreduction results between cysteine- and toluene-intercalated nontronite may be ascribed to the nature of organic matter-bacteria interactions. Whereas cysteine is an essential amino acid for bacteria and can also serve as an electron shuttle, thus enhancing the extent of Fe(3+) bioreduction and illitization, toluene is toxic and inhibits Fe(3+) reducing activity. This study, therefore, highlights the significant role of organic matter in promoting the smectite to illite reaction under conditions typical of natural environments (i.e., non-growth condition for bacteria).

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 2007
Accession Number
ADA499115

Entities

People

  • Andre J. Sommer
  • Gengxin Zhang
  • Hailiang Dong
  • Jinwook Kim

Organizations

  • University of Miami

Tags

Communities of Interest

  • Advanced Electronics

DTIC Thesaurus Topics

  • Amino Acids
  • Bacteria
  • Chemical Synthesis
  • Chemistry
  • Diffraction
  • Ecology
  • Electron Microscopes
  • Electron Microscopy
  • Environment
  • Essential Amino Acids
  • Microorganisms
  • Microscopy
  • Phyllosilicates
  • Spectra
  • Transmission Electron Microscopy
  • X Rays
  • X-Ray Diffraction

Fields of Study

  • Environmental science

Readers

  • Materials Science and Engineering.
  • Microbial Pathology
  • Space/Atmospheric Physics.

Technology Areas

  • Biotechnology
  • Biotechnology - Bioremediation
  • Microelectronics