The effect of adsorbed lipid on pyrite oxidation under biotic conditions
Jun Hao1, Curtis Cleveland1, Eelin Lim2, Daniel R Strongin1,3 and Martin AA Schoonen3
1Department of Chemistry, Temple University, Philadelphia, PA 19122, USA
2Department of Biology, Temple University, Philadelphia, PA 19122, USA
3Center for Environmental Molecular Science, Stony Brook University, Stony Brook, NY 11794-2100, USA
Geochemical Transactions 2006,
7:8doi:10.1186/1467-4866-7-8. [Open Access]
Abstract
The chemolithoautotrophic bacterium, Acidithiobacillus ferrooxidans,
commonly occurs in acid mine drainage (AMD) environments where it is
responsible for catalyzing the oxidation of pyrite and concomitant
development of acidic conditions. This investigation reports on the
growth of this bacterial species on the pyrite surface and in the
aqueous phase at a pH close to 2 as well as the role of adsorbed lipid
in preventing pyrite dissolution. Both acid washed pyrite and
acid-washed pyrite coated with lipids were used as substrates in the
studies. The choice of lipid, 1,2-bis(10,12-tricosadiynoyl)-sn-Glycero-3-Phosphocholine
lipid (23:2 Diyne PC), a phosphocholine lipid, was based on earlier
work that showed that this lipid inhibits the abiotic oxidation rate of
pyrite. Atomic force microscopy showed that under the experimental
conditions used in this study, the lipid formed ~4–20 nm layers on the
mineral surface. Surface-bound lipid greatly suppresses the oxidation
process catalyzed by A. ferrooxidans. This suppression
continued for the duration of the experiments (25 days maximum).
Analysis of the bacterial population on the pyrite surface and in
solution over the course of the experiments suggested that the pyrite
oxidation was dependent in large part on the fraction of bacteria bound
to the pyrite surface.
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