Formation of Sphalerite (ZnS) Deposits in Natural Biofilms of Sulfate-Reducing Bacteria

Labrenz, Matthias
Druschel, Gregory K.
Thomsen-Ebert, Tamara
Gilbert, Benjamin
Welch, Susan A.
Kemner, Kenneth M.
Logan, Graham A.
Summons, Roger E.
De Stasio, Gelsomina
Bond, Philip L.
Lai, Barry
Kelly, Shelly D.
Banfield, Jillian F.

¹Department of Geology and Geophysics, University of Wisconsin-Madison, 1215 West Dayton Street, Madison, WI 53706, USA. ²Diversions Scuba, Madison, WI 53705, USA. ³Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, WI 53706, USA. ⁴Argonne National Laboratory, Argonne, IL 60439, USA. ⁵Australian Geological Survey Organisation, GPO Box 378, Canberra ACT 2601, Australia.

*To whom correspondence should be addressed. E-mail: [email protected]

7 August 2000; accepted 6 October 2000

Science 290(5497):p 1744-1747, December 1, 2000.

Abundant, micrometer-scale, spherical aggregates of 2- to 5-nanometer-diameter sphalerite (ZnS) particles formed within natural biofilms dominated by relatively aerotolerant sulfate-reducing bacteria of the family Desulfobacteriaceae. The biofilm zinc concentration is about 10⁶ times that of associated groundwater (0.09 to 1.1 parts per million zinc). Sphalerite also concentrates arsenic (0.01 weight %) and selenium (0.004 weight %). The almost monomineralic product results from buffering of sulfide concentrations at low values by sphalerite precipitation. These results show how microbes control metal concentrations in groundwater- and wetland-based remediation systems and suggest biological routes for formation of some low-temperature ZnS deposits.