Nontronite Particle Aggregation Induced by Microbial Fe(III) Reduction and Exopolysaccharide Production
NAVAL RESEARCH LAB STENNIS SPACE CENTER MS SEAFLOOR SCIENCES DIRECTORATE
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Clay particle aggregation affects a number of environmental processes, such as contaminant sorptiondesorption, particle movementdeposition, and sediment structure and stability, yet factors that control clay aggregation are not well understood. This study was designed to investigate how microbial reduction FeIII in clay structure, a common process in soils and sediments, affects clay-particle aggregation. Microbial FeIII reduction experiments were conducted with Shewanella putrefaciens CN32 in bicarbonate buffer with structural FeIII in nontronite as the sole electron acceptor, lactate as the sole electron donor, and AQDS as an electron shuttle. Four size fractions of nontronite were used to evaluate size-dependent aggregation kinetics. The extent of FeIII bioreduction and the amount of exopolysaccharide EPS, a major biopolymer secreted by CN32 cells during FeIII bioreduction, were measured with chemical methods.
- Geology, Geochemistry and Mineralogy