Abstract
High-pressure is a key feature of deep subsurface environments. High partial pressure of dissolved gasses plays an important role in microbial metabolism, because thermodynamic feasibility of many reactions depends on the concentration of reactants. For gases, this is controlled by their partial pressure, which can exceed 1 MPa at in situ conditions. Therefore, high hydrostatic pressure alone is not sufficient to recreate true deep subsurface in situ conditions, but the partial pressure of dissolved gasses has to be controlled as well. We developed an incubation system that allows for incubations at hydrostatic pressure up to 60 MPa, temperatures up to 120°C, and at high gas partial pressure. The composition and partial pressure of gasses can be manipulated during the experiment. To keep costs low, the system is mainly made from off-the-shelf components with only very few custom-made parts. A flexible and inert PVDF (polyvinylidene fluoride) incubator sleeve, which is almost impermeable for gases, holds the sample and separates it from the pressure fluid. The flexibility of the incubator sleeve allows for sub-sampling of the medium without loss of pressure. Experiments can be run in both static and flow-through mode. The incubation system described here is usable for versatile purposes, not only the incubation of microorganisms and determination of growth rates, but also for chemical degradation or extraction experiments under high gas saturation, e.g., fluid–gas–rock-interactions in relation to carbon dioxide sequestration. As an application of the system we extracted organic compounds from sub-bituminous coal using H2O as well as a H2O–CO2 mixture at elevated temperature (90°C) and pressure (5 MPa). Subsamples were taken at different time points during the incubation and analyzed by ion chromatography. Furthermore we demonstrated the applicability of the system for studies of microbial activity, using samples from the Isis mud volcano. We could detect an increase in sulfate reduction rate upon the addition of methane to the sample.
Highlights
IntroductionThe incubation of deep subsurface microorganisms under highpressure conditions is necessary because under non-in situ conditions (especially low pressure) metabolic processes and survival of microorganisms adapted to high hydrostatic pressure are negatively impacted (Yayanos and Dietz, 1983; Fang et al, 2010)
We developed an incubation system that allows for incubations at hydrostatic pressure up to 60 MPa, temperatures up to 120 ̊C, and at high gas partial pressure
The incubation of deep subsurface microorganisms under highpressure conditions is necessary because under non-in situ conditions metabolic processes and survival of microorganisms adapted to high hydrostatic pressure are negatively impacted (Yayanos and Dietz, 1983; Fang et al, 2010)
Summary
The incubation of deep subsurface microorganisms under highpressure conditions is necessary because under non-in situ conditions (especially low pressure) metabolic processes and survival of microorganisms adapted to high hydrostatic pressure are negatively impacted (Yayanos and Dietz, 1983; Fang et al, 2010). Since the first isolation of a pressure-adapted bacterium by Yayanos et al (1979) numerous studies on the effect of elevated pressure on genetic, metabolic, and physiological aspects of microorganisms were carried out. Pressure was applied to a culture tube with a neoprene stopper working as piston for transmitting pressure to the sample. This type of pressure application is still being used today (Orcutt et al, 2008). Flexible cells made of gold (Seyfried, 1979) or titanium (Seyfried and Janecky, 1985) were www.frontiersin.org
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
