Projects

Collaborative Research: Experimental Controls on Clumped Isotope Signatures of CH4 in Deep-Sea Vents   

(NSF - OCE 2308386)

Foustoukos D.I., G.C. Lazar and J. Farquhar

Deep-sea hydrothermal vent systems affect the cycling of carbon between the Earth’s interior and oceans by introducing organic compounds of thermogenic, abiotic and microbial origin to the overlying water column. Vent fluids from both basalt and ultramafic-hosted hydrothermal systems contain abundant CH4 in addition to other organic species. This project focus on the stable C and H isotopic signatures of dissolved CH4 that provide insights on the temperature and mechanisms of formation. This proposal aims to explore the origin and evolution of CH4 in deep-sea vents by employing the use of double-substituted and doubly-deuterated isotopologues (13CH3D, 12CH2 D2 ). In a series of hydrothermal experiments involving organic matter decomposition. CO2  reduction and non-equilibrated CH4 gases in the presence of mineral catalysts, the distribution of rare methane isotopologue will be assessed by the use of a high-mass-resolution gas-source multiple collector mass spectrometer (Panorama, UMD). Experiments will assess the equilibrium relationships in the 12CH2 D2 -13CH3D-12CH3D-12CH4-13CH4-HD-HDO-H2O system and describe isotope effects associated with the impact of mineral phases and H2O H isotope composition on the abiotic and thermogenic formation mechanisms. This study aims to be a comprehensive study of 12CH2D2  and 13CH3D evolution applied to subseafloor hydrothermal systems and water/rock interactions deeper in the oceanic crust.

Physiological Adaptations in Hydrogenotrophic Bacteria at Extreme Pressures 

(NASA 80-NSSC-21K0485)

Foustoukos D. and Vetriani C.

We aim to constrain: i) the physiological adaptation of extremophiles to the pressure and nutrient levels found at deep-sea hydrothermal vents, and ii) phage-host interactions and coevolution. We will employ a novel anaerobic, chemolithoautotrophic and thermophilic Epsilonproteobacterium (Nautilia strain PV-1) that exhibits piezophilic growth. The genome of strain PV-1 carries a complete prophage. Task 1: How do piezophiles adapt to pressure gradients present at deep-sea and subsurface environments? We hypothesize that the membrane lipids saturation in Nautilia strain PV-1 decreases as the hydrostatic pressure increases. We will determine the changes in the membrane lipid composition (fatty acids and polar lipids) of strain PV-1 during growth at different pressures. Task 2: What is the role of environmental DNA uptake as an adaptation mechanism to pressure and nutrient-limitation stresses? We hypothesize that low and/or high pressure and nutrient availability regimes differentially affect the expression of DNA uptake genes in Nautilia strain PV-1 when exposed to exogenous DNA. We propose experiments to assess the level of expression of competence-related genes during the uptake of free DNA in strain PV-1. Task 3: We hypothesize that the life cycle of the prophage hosted in Nautilia strain PV-1 is affected by pressure and nutrient conditions that differ from those for optimum growth. We aim to: (i) investigate the pressure adaptation that triggers the lytic cycle of the bacteriophage; (ii) identify the nutrient regimes that trigger lytic cycle in PV-1; and (iii) investigate the ability of the PV-1 phage to infect its relatives in the order Nautiliales.

REU Site: Earth and Planetary science Interdisciplinary Internships at Carnegie (EPIIC) (NSF-GEO 2244322)

Foustoukos D.I. and J. Teske

The Earth and Planetary science Interdisciplinary Internships program at Carnegie will introduce the process of research at the intersections of: Astronomy, Astrobiology, Bio-/Isotope Geochemistry, Cosmochemistry, Data Science, Experimental Geochemistry, Geophysics, High-Pressure Mineral Physics, Mineralogy, Organic Geochemistry, and Petrology; to undergraduate students without significant previous research experience. The 10-week program is planned to ensure successful completion of students’ research activities and expects their participation in national meetings and peer-review publications. Students will be full members of their mentors’ research groups, attend weekly seminars and social events, and reside together on the campus of American University to help establish a collegial cohort. EPIIC’s intensity and training will prepare its participants for graduate student life. Maintaining student-mentor(s) communications beyond the summer REU program is encouraged to facilitate participant transition into STEM-related careers. The program will be evaluated by a series of surveys and tools employed under the guidance of an external advisor. The long-term success of the program success will be measured by: i) the number of REU students who follow a STEM-related career, including the number of community college students that transfer to a 4-year university as science majors, ii) the extent of the participation of students underrepresented in STEM education, iii) students’ understanding of the broader impacts of scientific discovery on the establishment of an ethical, inclusive and fact-driven society