Thermoanaerosceptrum fracticalcis gen. nov. sp. nov., a novel fumarate-fermenting microorganism from a deep fractured carbonate aquifer of the US great basin
Publication Year
2019
Type
Journal Article
Abstract
Deep fractured rock ecosystems across most of North America have not been studied extensively. However, the US Great Basin, in particular the Nevada National Security Site (NNSS, formerly the Nevada Test Site), has hosted a number of influential subsurface investigations over the years. This investigation focuses on resident microbiota recovered from a hydrogeologically confined aquifer in fractured Paleozoic carbonate rocks at 863 – 923 meters below land surface. Analysis of the microorganisms living in this oligotrophic environment provides a perspective into microbial metabolic strategies required to endure prolonged hydrogeological isolation deep underground. Here we present a microbiological and physicochemical characterization of a deep continental carbonate ecosystem and describe a bacterial genus isolated from the ecosystem. Strain DRI-13T is a strictly anaerobic, moderately thermophilic, fumarate-respiring member of the phylum Firmicutes. This bacterium grows optimally at 55◦ C and pH 8.0, can tolerate a concentration of 100 mM NaCl, and appears to obligately metabolize fumarate to acetate and succinate. Culture-independent 16S rRNA gene sequencing indicates a global subsurface distribution, while the closest cultured relatives of DRI-13T are Pelotomaculum thermopropionicum (90.0% similarity) and Desulfotomaculum gibsoniae (88.0% similarity). The predominant fatty acid profile is iso-C15: 0, C15: 0, C16: 0 and C14: 0. The percentage of the straight-chain fatty acid C15: 0 is a defining characteristic not present in the other closely related species. The genome is estimated to be 3,649,665 bp, composed of 87.3% coding regions with an overall average of 45.1% G + C content. Strain DRI-13T represents a novel genus of subsurface bacterium isolated from a previously uncharacterized rock-hosted geothermal habitat. The characterization of the bacterium combined with the sequenced genome provides insights into metabolism strategies of the deep subsurface biosphere. Based on our characterization analysis we propose the name Thermoanaerosceptrum fracticalcis (DRI-13T = DSM 100382T = ATCC TSD-12T). © 2019 Hamilton-Brehm, Stewart, Zavarin, Caldwell, Lawson, Onstott, Grzymski, Neveux, Lollar, Russell and Moser.
Keywords
carbonic acid,
fatty acid,
fumaric acid,
RNA 16S,
aquifer,
Article,
bacterial genome,
bacterial growth,
bacterial strain,
bacterium identification,
bacterium isolation,
Basin Groups,
biosphere,
cell growth,
Desulfotomaculum,
Desulfotomaculum gibsoniae,
DNA extraction,
ecosystem,
electron microscopy,
fermentation,
Firmicutes,
gene sequence,
genome analysis,
geochemical analysis,
geothermal energy,
ion chromatography,
lipid analysis,
microbial community,
microflora,
microorganism,
nonhuman,
Paleozoic,
Pelotomaculum thermopropionicum,
pH,
physical chemistry,
polymerase chain reaction,
rock,
scanning electron microscopy,
taxonomy,
Thermoanaerosceptrum fracticalcis,
transmission electron microscopy,
United States,
water analysis,
whole genome sequencing
Journal
Frontiers in Microbiology
Volume
10