Diversity of microorganisms within rock varnish in the Whipple Mountains, California

Abstract

Rock varnish from Arizona's Whipple Mountains harbors a microbial community containing about 10(8) 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 colonization.

FIG. 1.

Phylogenetic tree showing the relationships of bacterial 16S rRNA gene sequences to one another and to known microbial groups using 1,573 aligned characters. Nodal support values with bootstrap support (100 replicates) and posterior probabilities (10⁷ generations), respectively, are listed next to the branches of the unrooted maximum likelihood tree (ln L = −4,404.18186 [TrNef+I+Γ model]; p_inv = 0.512289; α = 0.599910). Line length, 0.1 substitutions/site; DRV, desert rock varnish isolate. Accession numbers are shown in boldface type or in parentheses.

FIG. 2.

Phylogenetic tree showing the relationships of eukaryotic 18S rRNA gene sequences to one another and to known microbial groups using 1,201 aligned characters. Nodal support values with bootstrap support (100 replicates) and posterior probabilities (10⁷ generations), respectively, are listed next to the branches of the unrooted maximum likelihood tree (ln L = −4,404.18186 [TrNef+I+Γ model]; p_inv = 0.512289; α = 0.599910). Line length, 0.1 substitutions/site; DRV, desert rock varnish isolate. Accession numbers are shown in boldface type or in parentheses.