Research article

The effect of adsorbed lipid on pyrite oxidation under biotic conditions

Jun Hao¹ , Curtis Cleveland¹ , Eelin Lim² , Daniel R Strongin^1,3 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

author email corresponding author email

Geochemical Transactions 2006, 7:8doi:10.1186/1467-4866-7-8

Published:	25 July 2006

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.