Probing the geological source and biological fate of hydrogen in Yellowstone hot springs

Abstract

Summary Hydrogen (H2) is enriched in hot springs and can support microbial primary production. Using a series of geochemical proxies, a model to describe variable H2 concentrations in Yellowstone National Park (YNP) hot springs is presented. Interaction between water and crustal iron minerals yields H2 that partition into the vapour phase during decompressional boiling of ascending hydrothermal fluids. Variable vapour input leads to differences in H2 concentration among springs. Analysis of 50 metagenomes from a variety of YNP springs reveals that genes encoding oxidative hydrogenases are enriched in communities inhabiting springs sourced with vapour‐phase gas. Three springs in the Smokejumper (SJ) area of YNP that are sourced with vapour‐phase gas and with the most H2 in YNP were examined to determine the fate of H2. SJ3 had the most H2, the most 16S rRNA gene templates and the greatest abundance of culturable hydrogenotrophic and autotrophic cells of the three springs. Metagenomics and transcriptomics of SJ3 reveal a diverse community comprised of abundant populations expressing genes involved in H2 oxidation and carbon dioxide fixation. These observations suggest a link between geologic processes that generate and source H2 to hot springs and the distribution of organisms that use H2 to generate energy.

Phylogenomic analysis of novel Diaforarchaea is consistent with sulfite but not sulfate reduction in volcanic environments on early Earth

“…Additional geochemical data were gathered for MV2 (also referred to as " Figure 8" pool) from previously published studies [26,27]. SJ3 spring is located within the Smokejumper Geyser Basin (N 44°24′57.42″, W −110°57′20.76″), and the sampling details, field measurements, and geochemistry of SJ3 are reported in detail elsewhere [28,29].…”

“…Expression of dsrA in the MV2-Eury population was investigated in six MV2 samples collected between July 2016 and July 2018 ( Supplementary Table S1). A slightly modified version of the FastRNA Pro Soil-Direct kit (MP Biomedicals, Irvine, CA, USA) was used to extract RNA from MV2 sediments, as previously described [29]. Briefly, RNA extracts were DNAse-treated (Sigma-Aldrich, St. Louis, MO, USA) and subjected to PCR of 16S rRNA genes to determine if DNA persisted, as described previously [29].…”

“…A slightly modified version of the FastRNA Pro Soil-Direct kit (MP Biomedicals, Irvine, CA, USA) was used to extract RNA from MV2 sediments, as previously described [29]. Briefly, RNA extracts were DNAse-treated (Sigma-Aldrich, St. Louis, MO, USA) and subjected to PCR of 16S rRNA genes to determine if DNA persisted, as described previously [29]. cDNA was then synthesized using the iScript cDNA synthesis kit (Bio-Rad Laboratories, Hercules, CA, USA) in 20 µL reactions.…”

Editorial: Microbial Hydrogen Metabolism

“…A wide range of ecosystems have now been described where H 2 cycling supports the bulk of primary production and where it forms the basis by which species interact, leading to ecologically structured communities. Much of the research on H 2 metabolism to date has focused on ecosystems where H 2 is present at elevated concentrations due to biological activity (e.g., anoxic sediments, gastrointestinal tracts; Sørensen et al, 1981;Wolf et al, 2016;Greening et al, 2019;Kessler et al, 2019) or geological activity (e.g., hydrothermal vents, subsurface systems; Petersen et al, 2011;Brazelton et al, 2012;Telling et al, 2015;Dong et al, 2019;Lindsay et al, 2019). More recently, it has been recognized that atmospheric H 2 can serve as source of reductant for aerobic soil microorganisms and that this can influence the composition of the atmosphere (Conrad, 1996;Constant et al, 2010;Ji et al, 2017;Cordero et al, 2019).…”

Geologic legacy spanning >90 years explains unique Yellowstone hot spring geochemistry and biodiversity

“…S° is chemically stable at temperatures <100°C (Nordstrom et al ., ), a characteristic that can lead to its accumulation in acidic springs where it can serve as an electron donor, acceptor, or both donor and acceptor (e.g., disproportionation) in microbial metabolism (Amenabar and Boyd, ). Moreover, acidic springs sourced by vapour phase gases are also likely to be enriched in volatiles such as H 2 S, hydrogen (H 2 ) and methane (CH 4 ) (Lindsay et al ., ) and have higher total sulphur contents, including solid phase S° and its oxidation product SO 4 2− , relative to alkaline springs (Nordstrom et al ., ; Amenabar and Boyd, ).…”