Clara S. Chan of the University of California at Berkeley and her colleagues studied a microbe recovered from an abandoned, flooded iron mine in southwestern Wisconsin. This microbe exudes particularly wispy fibers, which become covered in iron-oxide crystals. These crystallized filaments are unusual in their proportions, which are comparable to those of a human hair. Analysis of the hairlike fibers using high-resolution microscopes revealed the chemical processes that govern their formation. The microbes most likely use a so-called redox reaction to gather energy from their iron-rich surroundings, the researchers report. "The product, ferric iron, then precipitates" and affixes to the polymers attached to the microbial cell, study co-author Jill Banfield of the University of California at Berkeley explains.
Danielle Fortin of the University of Ottawa notes in an accompanying editorial that a clear understanding of how the bugs can encourage mineral crystallization is "crucial because it might lead to the development of new tools in the search for evidence of past life on Earth and other planets." In addition, deciphering these biomineralization mechanisms, the authors observe, could aid the fabrication of novel materials. Already they have succeeded in manufacturing similar filaments in the laboratory. Remarks Banfield, "The hope is that this may inspire new routes for biomimetic synthesis."