『Abstract
We investigated interactions between ferruginous smectite (NAu-1)
and facultative dissimilatory iron-reducing bacteria, Shewanella
oneidensis, in order to determine whether the bacteria are
directly respiring structural Fe(III) or respiring Fe(III) after
it has been dissolved from the structure of the clay. anaerobic
flow-through experiments were used to facilitate the microbial
reduction under controlled solution chemistry and to monitor the
time-dependent concentrations of Fe, Al, and Si, which are major
structural components of NAu-1. Complimentary batch experiments
were conducted to allow for time series examinations of the reacted
solid and extensive control experiments. The control experiments
revealed that NAu-1 dissolution occurred under anaerobic, aerobic,
biotic, and abiotic conditions even when Fe remained oxidized
due to the presence of O2 or absence of viable
bacteria. Thus, this study shows that NAu-1 dissolution precedes
microbial reduction of Fe. The dissolution products of this dynamic
system are present not only in solution, but also as secondary
precipitates and/or adsorbates. Thus, S. oneidensis in
our systems are primarily respiring Fe(III) in the aqueous phase
or associated with secondary solids, rather than Fe(III) that
is still a part of the crystalline NAu-1 structure.
Keywords: Nontronite; Miscible flow study; TEM; Anaerobic bacteria;
Iron; Reduction; Dissolution; Shewanella oneidensis; Smectite』
1. Introduction
2. Materials and methods
2.1. Clay mineral preparation
2.2. Bacterial cultures
2.3. Flow studies
2.4. Batch studies
2.5. Total Fe(II) analysis
2.6. Transmission electron microscopy
3. Results and discussion
4. Conclusions
Acknowledgements
References