In situ Electrochemical Studies of the Terrestrial Deep Subsurface Biosphere at the Sanford Underground Research Facility, South Dakota, USA

Microbial Signatures in Deep CO2-Saturated Miocene Sediments of the Active Hartoušov Mofette System (NW Czech Republic)

“…Furthermore, Mu et al (2014) observed an increase of Comamonadaceae after the injection of CO 2 into the Paaratte sandstone aquifer (Southern Australia) and a similar result was reported by Gulliver et al (2018) for the CO 2 injection into an aquifer at the freshwater Plant Daniel in Escatawpa (Massachusetts, USA). Although, Comamonadaceae have been found in non-CO 2 influenced subsurface environments such as the Sanford Underground Research Facility (Jangir et al, 2019) and the Fennoscandian shield (Nyyssönen et al, 2014), the relative abundances in these environments were lower compared to our results. Thus, the dominance of members from the family Comamonadaceae in the deep sediments of the Hartoušov mofette seem to reflect a CO 2 influenced microbial community with a good adaptation potential to the prevailing conditions.…”

Microbial electroactive biofilms dominated by Geoalkalibacter spp. from a highly saline–alkaline environment

“… Exoelectrogens tested at neutral pH and high salinity a. Geoalkalibacter subterraneus −0.19 0.015 17 b. Geoalkalibacter subterraneus −0.401, −0.382 −0.196 23 c. Haloferax volcanii −0.300, 0.100 −0.095, 0.305 24 3. Exoelectrogens tested at high saline–alkaline conditions a. Geoalkalibacter ferrihydriticus −0.21 −0.005 21 b. Mixed-culture biofilm −0.176, −0.131 0.029, 0.074 26 c. Geoalkalibacter spp.-dominated biofilm 0.18, 0.33 0.385, 0.535 This study SHE standard hydrogen electrode. …”

“…Very few studies have reported on the diversity of EAMs from extreme environments. These include, for instance, highly saline 17 – 19 , extreme acidic 20 and alkaline 21 , extreme low 22 and high temperature 19 , 23 , high temperature and pressure 24 , 25 , and deep subsurface 26 habitats. A combination of some of these extreme conditions also exists in some environments.…”

Using Cathodic Poised Potential Experiments to Investigate Extracellular Electron Transport in the Crustal Deep Biosphere of North Pond, Mid-Atlantic Ridge

“…There are microbial cells present in this environment, often in very low cell densities (Orcutt et al, 2011b;Smith et al, 2011;Jungbluth et al, 2013Jungbluth et al, , 2016Jørgensen and Zhao, 2016;Meyer et al, 2016;Labonté et al, 2017;Früh-Green et al, 2018). Studies documenting the potential for microbial activity in the crustal subsurface (Torsvik et al, 1998;Lever et al, 2013;Orcutt et al, 2013a;Meyer et al, 2016;Robador et al, 2016;Zhang et al, 2016;D'Hondt et al, 2019;Jangir et al, 2019) indicate relatively low rates of activity consistent with the limiting resource and energy conditions in the subsurface (LaRowe and Amend, 2015;Bradley et al, 2018;Jones et al, 2018).…”

“…There are a growing number of anodic electrochemical studies in environmental samples to identify electrode-reducing EET-capable microorganisms (e.g., Bond et al, 2002;Williams et al, 2010;Reimers et al, 2017;Lam et al, 2019a). However, there are far fewer cathodic or electrodeoxidizing studies to identify environmental microorganisms capable of solid substrates as electron donors (Gregory et al, 2004;Strycharz-Glaven et al, 2013;Rowe et al, 2015Rowe et al, , 2018Jangir et al, 2019;Lam et al, 2019b). While EET-capable microbes are confirmed in the deep terrestrial subsurface (Summers et al, 2013;Badalamenti et al, 2016;Jangir et al, 2016Jangir et al, , 2019Karbelkar et al, 2016) and deep marine hydrothermal vents (Yamamoto et al, 2017;Pillot et al, 2018), to our knowledge there have been no studies in oceanic crust.…”