| Diversity
of Microorganisms within Rock Varnish in the Whipple Mountains,
California†
K. R. Kuhlman,1* W. G.
Fusco,2 M. T. La Duc,1 L. B. Allenbach,2
C. L. Ball,2 G. M. Kuhlman,1 R. C. Anderson,1
I. K. Erickson,3 T. Stuecker,1 J. Benardini,2
J. L. Strap,2 and R. L. Crawford2
Planetary Science Institute, 1700 East Fort Lowell Rd.,
Suite 106, Tucson, AZ 85719.
Abstract
Rock varnish from Arizona’s Whipple
Mountains harbors a microbial community containing about 108
microorganisms g-1 of varnish. Analyses of varnish
phospholipid fatty acids and rRNA gene libraries reveal a
community comprised of mostly Proteobacteria but
also including Actinobacteria, eukaryota, and a few
members of the Archaea. Rock varnish represents a
significant niche for microbial colonizationRock varnish (also
known as desert varnish) is a dark, thin (usually 5 to 500
 m thick), layered veneer composed
of clay minerals cemented together by oxides and hydroxides
of manganese and iron (11, 20, 56, 63, 64). Nineteenth century
references to rock varnish include those of Humboldt (42)
and Darwin (14). Modern observations of varnish were initiated
with the studies of Laudermilk (49) and Engel and Sharp (25);
however, despite decades of study, the nucleation and growth
mechanisms of rock varnish remain a mystery (11, 18, 37, 44,
57, 58).
Keywords:microbial community;microorganisms
g-1;phospholipid fatty acids;eukaryota;rRNA gene;Proteobacteria;Actinobacteria;Archaea;taxonomy.
Corresponding author: Tel (520) 622-6300;
Fax (520) 622-8060
E-mail: kim@psi.edu |
