Earth and Planetary Science
EPS Planetary Science

JUL 2007 - Extracellular Proteins Limit the Dispersal of Biogenic Nanoparticles

In their recently published paper in Science (reprint), recent EPS Ph.D. graduate John Moreau and Prof. Jill Banfield, along with colleagues from Lawrence Berkeley and Lawrence Livermore National Labs, demonstrated the presence of extracellular biofilm proteins inside bacterially-formed aggregates of nanocrystalline zinc-sulfide (orange and yellow features in image). These proteins promoted the rapid aggregation of sulfide nanoparticles formed by bacterial sulfate reduction in an abandoned flooded mine, and thereby restricted the dispersal of contaminant metals such as zinc, arsenic and selenium. In nature, metal-binding proteins associated with sulfate-reducing bacteria or biofilm formation may serve to inhibit the mobility of nanoparticulate or colloidal toxic metals away from their source.