R. Schmidt E.D. Swanner K.W. Mandernack A.S. Templeton Thomas L. Kieft R. L. Smith W. E. Sanford R.L. Callaghan J.B. Mitton J.R. Spear J.W. Sahl 2008 <div id="abstract-1" class="section abstract"><p id="p-1">A microbial community analysis using 16S rRNA gene sequencing was performed on borehole water and a granite rock core from Henderson Mine, a &gt;1,000-meter-deep molybdenum mine near Empire, CO. Chemical analysis of borehole water at two separate depths (1,044 m and 1,004 m below the mine entrance) suggests that a sharp chemical gradient exists, likely from the mixing of two distinct subsurface fluids, one metal rich and one relatively dilute; this has created unique niches for microorganisms. The microbial community analyzed from filtered, oxic borehole water indicated an abundance of sequences from iron-oxidizing bacteria (<i>Gallionella</i><span>&nbsp;</span>spp.) and was compared to the community from the same borehole after 2 weeks of being plugged with an expandable packer. Statistical analyses with UniFrac revealed a significant shift in community structure following the addition of the packer. Phospholipid fatty acid (PLFA) analysis suggested that<span>&nbsp;</span><i>Nitrosomonadales</i><span>&nbsp;</span>dominated the oxic borehole, while PLFAs indicative of anaerobic bacteria were most abundant in the samples from the plugged borehole. Microbial sequences were represented primarily by<span>&nbsp;</span><i>Firmicutes</i>,<span>&nbsp;</span><i>Proteobacteria</i>, and a lineage of sequences which did not group with any identified bacterial division; phylogenetic analyses confirmed the presence of a novel candidate division. This “Henderson candidate division” dominated the clone libraries from the dilute anoxic fluids. Sequences obtained from the granitic rock core (1,740 m below the surface) were represented by the divisions<span>&nbsp;</span><i>Proteobacteria</i><span>&nbsp;</span>(primarily the family<span>&nbsp;</span><i>Ralstoniaceae</i>) and<span>&nbsp;</span><i>Firmicutes</i>. Sequences grouping within<span>&nbsp;</span><i>Ralstoniaceae</i><span>&nbsp;</span>were also found in the clone libraries from metal-rich fluids yet were absent in more dilute fluids. Lineage-specific comparisons, combined with phylogenetic statistical analyses, show that geochemical variance has an important effect on microbial community structure in deep, subsurface systems.</p></div> application/pdf 10.1128/AEM.01133-07 en ASM Subsurface microbial diversity in deep-granitic-fracture water in Colorado article