Microbial production of natural gas in subsurface organic-rich reservoirs (e.g. coal, shale, oil) can be enhanced by the introduction of limiting nutrients to stimulate microbial communities to generate “new” methane resources on human timescales. The few successful field experiments of Microbial Enhancement of Coalbed Methane (MECoM) relied on relatively qualitative approaches for estimating the amount of “new” methane produced during the stimulation process (i.e. extrapolation of pre-stimulation gas production curves). We have tested deuterated water as a tracer, initially in the laboratory, to more directly quantify the amount of “new” methane generated and the effectiveness of MECoM stimulation approaches. Microorganisms, formation water, and coal obtained during a previous drilling project in the Powder River Basin, Birney, Montana were used to set up a series of benchtop stimulation experiments where we added incremental amounts of deuterated water to triplicate sets of stimulated microbes (methanogens). We hypothesized that as MECoM progresses, methanogens will incorporate the heavy water into new methane produced, as methanogens naturally uptake hydrogen during methanogenesis. The amount of hydrogen incorporated into methane from water is dependent on the methanogenic pathway (hydrogenotropic vs acetoclastic/methylotrophic). During the experiments, we saw a shift in the methanogenic pathway towards acetoclastic methanogenesis, which was indicated by a consistent shift in the enrichment of deuterium in the methane produced, methanogenic community, and a large kinetic fractionation. The enrichment of the methane as compared to the deuterium content of the water the microbes used followed a narrowly confined, predictable range of values. This predictable enrichment of the methane allows us to propose a quantification scheme for the amount of methane produced in larger field scale stimulations, as we can compare the change in the overall deuterium content of the in-situ methane with the known value before the stimulation. The success of our proof-of-concept laboratory experiments suggests that deuterium may be used as a tracer of “new” natural gas resources in field- to commercial-scale MECoM projects. In addition, additions of deuterated water may also be useful as a tracer in bioremediation projects where large background pools of contaminants or degradation products hamper traditional quantification techniques, microbial enhanced oil recovery, or other subsurface carbon cycling pathways.

Les leucémies aiguës myéloïdes (LAM) du sujet âgé sont les plus fréquentes des leucémies aiguës. Bien que de physiopathologie hétérogène, elles partagent un pronostic défavorable. L’azacitidine est devenue un des traitements de référence pour les patients jugés inéligibles pour une chimiothérapie intensive mais les critères de sélection des patients entre ces deux approches sont controversés. L’identification de biomarqueur prédictif de réponse à l’azacitidine doit permettre de rationnaliser ce choix thérapeutique. Les facteurs pronostiques classiques d’une cohorte de 334 patients atteints de LAM manquent de précision pour guider la meilleure stratégie pour un patient donné. A partir du séquençage de 224 patients traités par azacitidine, nous montrons un impact défavorable des mutations de TP53 sur la survie globale, quel que soit leur caractérisation fonctionnelle. Le séquençage des exomes de 49 patients selon leur réponse à l’azacitidine (26 répondeurs et 23 non répondeurs), suivi du re-séquençage ciblé de 4 polymorphismes chez 175 patients a montré un impact positif du polymorphisme rs7622799 de MECOM sur la survie globale sous azacitidine. / Elderly patients with acute myeloid leukemias (AML) represent the most frequent acute leukemias. Although they differ in their pathophysiology, they all share an adverse prognosis. Azacitidine has become one of the reference low-intensity frontline therapy for patients deemed unfit for intensive chemotherapy. Patients selection between these 2 options remains controversial. Predictive biomarkers of response to azacitidine should allowed to rationalize this decision making. Classical prognosis factors of a cohort of 334 newly diagnosed AML lack of precision to determine the optimum strategy for any individual patient. By sequencing of a 224-patients series of azacitidine-treated AML patients, we demonstrate an adverse impact of TP53 mutation on overall survival, irrespective of the functional characterization of p53 mutants. Exome sequencing of 49 patients with extreme phenotype as defined by their response under azacitidine (26 responders versus 23 non-responders), followed by targeted sequencing of 4 common polymorphisms in a validation set of 175 patients, showed a positif impact of MECOM rs7622799 on overall survival.

Natural gas is an important transitional energy source to replace more carbon intensive coal combustion in the face of climate change and increasing global energy demands. A significant proportion of natural gas reserves (~20%) were recently generated by microorganisms that degrade organic-rich formations (i.e. coal, shale, oil) in-situ to produce methane. Recent studies have shown that these microbial communities may be potentially stimulated to generate more methane to extend the lifetime (~10 years) of existing biogenic gas wells. This dissertation investigates how microbial coalbed methane (CBM) systems are impacted by geochemical conditions, microbial community composition, and groundwater recharge. The first study is a review and synthesis of existing basic research and commercial activities on enhancement of microbial CBM generation, and identification of key knowledge gaps that need to be addressed to advance stimulation efforts. The second study couples water and gas geochemistry with characterization of microbial communities in coalbeds in the Powder River Basin (PRB), Wyoming to investigate the influence of microbiology on water and gas geochemistry. Geochemistry results indicated that nutrients are likely source in situ from coal, and that all sulfate must be removed from the system before methanogenesis will commence. Increased archaeal (i.e. methanogens) diversity was observed with decreasing sulfate concentration, while sulfate reducing bacterial communities were different in wells with high sulfate concentrations (sulfate reducing conditions) when compared to wells with low sulfate concentrations (methanogenic conditions). The third study uses noble gases to constrain the residence time of groundwater associated with CBM in the PRB. Measured diffusional release rates of 4He from PRB coals were ~800 times greater than typical rates observed in sandstone or carbonate aquifers, and measured 4He values far exceeded expected values from in-situ decay of U and Th. Groundwater 4He residence times ranged from <1 to ~800 years using the measured diffusion rates versus ~130 to 190,000 years using a standard model. Coal waters with the longest residence time had the highest alkalinity concentrations, suggesting greater extents of microbial methanogenesis, although there was no relationship between groundwater "age" and methane concentrations or isotopic indicators of methanogenesis. Constraining the relationship between microbial activity (e.g. mechanisms of coal biodegradation and methane generation), environmental geochemical conditions, and groundwater flow is important to better understand subsurface hydrobiogeochemical processes and to ensure the success of future projects related to stimulation of microbial CBM.