Exploring Microbe-Microbe and Microbe-Environment Interactions in Acidiphilium cryptum and Acidithiobacillus ferrooxidans: A Model Contaminant Metal Redox Cycling System
EMSL Project ID
39728
Abstract
Dissimilatory metal-respiring bacteria (DIRB) of widely differing phylogenetic and ecophysiologic affiliation share one distinct physiologic feature-the copious production of redox-active extracellular biomaterials that enable electron transport from electron donors (organic carbon and/or hydrogen) to electron acceptors such as iron, uranium, and chromium. It is possible that a common system exists for solving the extracellular electron transport problem at low and neutral pH, namely, extracellular structures such as outer membrane vesicles (OMVs). This mechanism is plausible based on thermodynamic considerations, and has now been observed in both neutrophile and acidophiles. The goals of this study will be to 1) use electron microscopy coupled with isotopically labeled substrates to establish spatial arrangements of cells, OMVs, and metals/metal oxides in a biofilm matrix, 2) establish proteomic profiles of OMVs and periplasmic and extracellular fractions in a two-member biofilm (Acidithiobacillus ferrooxidans and A. cryptum), and 3) use high-resolution NMR to examine protein- and OMV-mineral interactions. These studies will confirm or deny the existence and functionality of OMVs as they pertain to Fe, U, and Cr transformation, and will determine structure and composition of the extracellular materials. Extracellular electron transport is still poorly understood, and in spite of a few recent significant contributions, many questions remain to be answered. Understanding of acidophilic and other 'extremophilic' metal transforming organisms remains a top priority, since there are documented examples of contaminated subsurface environments where severe conditions exist. Of equal importance is the development of unique spectroscopy and microscopy approaches that will be required for the study of these structures. The EMSL's expertise with technologies such as NMR, electron microscopy and proteomics will be necessary to fully explore the extracellular composition of single and mixed species biofilms in this case. While some academic institutions cannot offer any, or all of these technologies, using EMSL resources will allow a complete examination of OMVs associated with single and mixed species biofilms.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2010-10-01
End Date
2012-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Cort JR, M Swenson, and TS Magnuson. 2011. "1H, 13C, and 15N backbone, side-chain, and heme chemical shift assignments for oxidized and reduced forms of the monoheme c-type cytochrome ApcA isolated from the acidophilic metal-reducing bacterium Acidiphilium cryptum." Biomolecular NMR Assignments 5(1):89-92. doi:10.1007/s12104-010-9274-1
Magnuson TS. 2011. "How the xap Locus Put Electrical “Zap” in Geobacter sulfurreducens Biofilms." Journal of Bacteriology 193(5):1021-1022. doi:10.1128/JB.01478-10