Abstract：
Hyperthermophilic archaean Methanocaldococcus sp. FS406-22 (hereafter FS406) is a hydrogenotrophic methanogen isolated from a deep-sea hydrothermal vent. To better understand the energetic requirements of hydrogen oxidation under extreme conditions, the thermodynamic characterization of FS406 incubations is necessary and notably underexplored. In this work, we quantified the bioenergetics of FS406 incubations at a range of temperatures (65, 76, and 85 ℃) and hydrogen concentrations (1.1, 1.4, and 2.1 mm). The biomass yields (C-mol of biomass per mol of H2 consumed) ranged from 0.02 to 0.19. Growth rates ranged from 0.4 to 1.5 h-1. Gibbs energies of incubation based on macrochemical equations of cell growth ranged from - 198 kJ/C-mol to - 1840 kJ/C-mol. Enthalpies of incubation determined from calorimetric measurements ranged from - 4150 kJ/C-mol to - 36333 kJ/C-mol. FS406 growth rates were most comparable to hyperthermophilic methanogen Methanocaldococcus jannaschii. Maintenance energy calculations from the thermodynamic parameters of FS406 and previously determined heterotrophic methanogen data revealed that temperature is a primary determinant rather than an electron donor. This work provides new insights into the thermodynamic underpinnings of a hyperthermophilic hydrothermal vent methanogen and helps to better constrain the energetic requirements of life in extreme environments.
摘要：
嗜高温古生甲烷球菌。FS406-22（以下简称FS406）是从深海热液喷口分离出的氢营养型产甲烷菌。为了更好地了解极端条件下氢氧化的能量要求，FS406孵化的热力学表征是必要的，特别是开发不足。在这项工作中,我们量化了在一定温度范围(65,76和85℃)和氢浓度(1.1,1.4和2.1mm)下FS406孵化的生物能量学。生物质产率（每摩尔消耗的H2的C-mol生物质）范围为0.02至0.19。生长速率范围为0.4至1.5h-1。根据细胞生长的宏观化学方程，孵育的吉布斯能量范围为-198kJ/C-mol至-1840kJ/C-mol。从量热测量确定的孵育焓范围为-4150kJ/C-mol至-36333kJ/C-mol。FS406的生长速率与嗜高温产甲烷菌最相似。根据FS406的热力学参数和先前确定的异养产甲烷菌数据进行的维持能量计算表明，温度是主要的决定因素，而不是电子供体。这项工作为超热热液喷口产甲烷菌的热力学基础提供了新的见解，并有助于更好地限制极端环境中生命的能量需求。
