BioMARSMetal cycling,
Microbes, and
Organic Biomolecules
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Metal cycling, Microbes, and Organic Biomolecules

Jillian F. Banfield, William Dietrich, Michael Manga, Javiera Cervini-Silva (University of California at Berkeley) and Janice Bishop (SETI Institute)

     Organisms adapted to both acidic and neutral pH environments participate in iron and sulfur cycling. We have explored the role of extracellular polymers associated with neutrophilic iron-oxidizing bacteria in templating the crystallization of iron oxyhydroxide minerals with novel morphologies. Our results show that alginate-like organic threads accumulate a poorly crystalline precipitate and direct the growth of curved pseudo-single crystals of an unexpected structure, akaganeite, with very large aspect ratios (Chan et al.). These materials would not be expected in the absence of biological templates. At very low pH, we have studied the assembly of subsurface microbial communities sustained by iron oxidation. We have used culture-independent methods to investigate the abundance, distribution, and metabolism of an unexpected archaeal member that can not be detected using typical PCR-based approaches. We have also explored the interactions between organic polymers and mineral surfaces and discovered new pathways for both depolymerization and polymerization of organic carbon compounds (Cervini-Silva and Banfield (in review); Cervini-Silva et al. (in review).

Department of Astronomy    601 Campbell Hall    Berkeley, CA 94720-3411    510-643-2457