view in mine showing biofilm containing ARMAN

© and courtesy Jill Banfield.

The biofilm containing ARMAN is visible as a pink streak near the bottom center.

The smallest free-living (at least part of the time) living things, if viruses are considered non-living. They are 200 – 400 nanometers in diameter and belong to the domain Archaea.

They were discovered in the highly acidic waters (about pH 1, equivalent to automobile battery acid) of an abandoned copper mine in northern California. The name is an acronym for “Archaeal Richmond Mine Acidophilic Nanoorganisms” (but it is also the surname of the mine's owner, Ted Arman).


courtesy Luis Comolli, Lawrence Berkeley NL

The circular orange object is an ARMAN cell. Above it is another ARMAN cell, probably dying, which has swollen to a diameter of about 1,000 nanometers. The small yellow canoe-shaped objects are viruses that infect ARMAN cells.


Brett J. Baker, Gene W. Tyson, Richard I. Webb, Judith Flanagan, Philip Hugenholtz, Eric E. Allen, and Jillian F. Banfield.
Lineages of Acidophilic Archaea Revealed by Community Genomic Analysis.
Science, vol. 314, no. 5807, pages 1933-1935 (22 December 2006).

Brett J. Baker, Luis R. Comolli, Gregory J. Dick, Loren J. Hauser, Doug Hyatt, Brian D. Dill, Miriam L. Land, Nathan C. VerBerkmoes, Robert L. Hettich, and Jillian F. Banfield.
Enigmatic, ultrasmall, uncultivated Archaea.
Publications of the National Academy of Science (US), vol. 107, no. 19 (11 May 2010).


Wikipedia has an excellent entry on ARMAN:

An informative press release from UC Berkeley:

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