Isolation, Characterization, and Ecology of Sulfur-Respiring Crenarchaea Inhabiting Acid-Sulfate-Chloride-Containing Geothermal Springs in Yellowstone National Park

Abstract

Elemental sulfur (S 0 ) is associated with many geochemically diverse hot springs, yet little is known about the phylogeny, physiology, and ecology of the organisms involved in its cycling. Here we report the isolation, characterization, and ecology of two novel, S 0 -reducing Crenarchaea from an acid geothermal spring referred to as Dragon Spring. Isolate 18U65 grows optimally at 70 to 72°C and at pH 2.5 to 3.0, while isolate 18D70 grows optimally at 81°C and pH 3.0. Both isolates are chemoorganotrophs, dependent on complex peptidecontaining carbon sources, S 0 , and anaerobic conditions for respiration-dependent growth. Glycerol dialkyl glycerol tetraethers (GDGTs) containing four to six cyclopentyl rings were present in the lipid fraction of isolates 18U65 and 18D70. Physiological characterization suggests that the isolates are adapted to the physicochemical conditions of Dragon Spring and can utilize the natural organic matter in the spring as a carbon and energy source. Quantitative PCR analysis of 16S rRNA genes associated with the S 0 flocs recovered from several acid geothermal springs using isolate-specific primers indicates that these two populations together represent 17 to 37% of the floc-associated DNA. The physiological characteristics of isolates 18U65 and 18D70 are consistent with their potential widespread distribution and putative role in the cycling of sulfur in acid geothermal springs throughout the Yellowstone National Park geothermal complex. Based on phenotypic and genetic characterization, the designations Caldisphaera draconis sp. nov. and Acidilobus sulfurireducens sp. nov. are proposed for isolates 18U65 and 18D70, respectively.

CO 2 Uptake and Fixation by a Thermoacidophilic Microbial Community Attached to Precipitated Sulfur in a Geothermal Spring

“…In addition, submerged substrata at the spring's source are blanketed by precipitates of elemental sulfur (S°), hereafter referred to as S o floc (23). Inventories of bacterial and archaeal 16S rRNA genes recovered from S o floc collected from the source of Dragon Spring indicate the presence of Crenarchaeota and Aquificae (4,15). The latter are related to chemolithoautotrophic Hydrogenobaculum spp., representatives of which have recently been isolated from the spring (15).…”

Geoarchaeota: a new candidate phylum in the Archaea from high-temperature acidic iron mats in Yellowstone National Park

“…(10-15%) as determined by three separate phylogenetic methods. All three of these organisms are B1 mm diameter cocci (Boyd et al, 2007;Kozubal et al, 2008;this study). Most of the remaining sequences belong to Vulcanisaeta-or Hydrogenobaculum-like spp.…”

[FeFe]-hydrogenase in Yellowstone National Park: evidence for dispersal limitation and phylogenetic niche conservatism

“…DNA extraction and PCR amplification of hydA Approximately 100 mg of microbial mat or sediment was subjected to community genomic DNA extraction, purification, and quantification as earlier described (Boyd et al, 2007). All DNA extracts were screened for the presence of 16S rRNA genes to ensure the presence of PCR-amplifiable DNA by using 10 ng of DNA, and primers bacterial 1070F (5 0 -ATGGCTGTCGTCAGCT-3 0 ) and universal 1492R (5 0 -GGTTACCTTGTTACGACTT-3 0 ) (Boyd et al, 2009a).…”