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 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 colonization.

Spatial, temporal and geographic considerations of the problem of rock varnish diagenesis

“…Analyses of 'bulk samples' (i.e., those requiring the scraping of varnish and underlying weathering rind and rock material) have included analysis of amino acids (Warsheid, 1990;Nagy et al, 1991;Perry and Kolb, 2003;, isotopic analysis (Dorn and DeNiro, 1985), analysis of fatty acid methyl esters (Schelble et al, 2005), phospholipid fatty acids (Kuhlman et al, 2006a), and extraction of genetic material for phylogenetic insight (Eppard et al, 1996;Kuhlman et al, 2005;Spilde et al, 2005;Benzerara et al, 2006;Kuhlman et al, 2006a,b;Northup et al, 2010).…”

Stone-dwelling actinobacteria Blastococcus saxobsidens, Modestobacter marinus and Geodermatophilus obscurus proteogenomes

“…Consequently, stone surfaces can be colonized by these wind-borne microbes . These surfaces are often covered with growth (called 'patinas', 'varnish-like' or 'tintenstriches'), which comprises complex communities of eukaryotes and prokaryotes, recurrent among which are Actinobacteria (Eppard et al, 1996;Kuhlman et al, 2006) including Geodermatophilaceae (Urzi et al, 2001). With regard to biopitting, one hypothesis is that acid secretion and high carbon dioxide (CO 2 ) emissions from combustion engines result in alternating episodes of calcareous solubilization and precipitation.…”

Desert Crusts and Rock Coatings

“…Dorn and Dragovich (1990) successfully cultured nine Mn-oxidising bacteria, and the dendritic patterns in some varnishes are similar to those produced during Fe and Mn oxidation by Bacillus cereus (Billy and Cailleux, 1968). Rock varnishes are 'home' to vast numbers of bacteria, with analyses of samples collected from desert pavement cobbles in eastern California revealing the presence of 10 8 cells of bacteria per gram dry weight of varnish (Kuhlman et al, 2005(Kuhlman et al, , 2006. There are, however, two major limitations of the biogenic model.…”