Key role of hydrogen in regulating hydrogenases and the reductive TCA cycle in a thermophilic, autotrophic sulfur-reducing bacterium

Understanding how thermophilic, autotrophic sulfur-reducing bacteria such as <i>Desulfurobacterium thermolithotrophum</i> adapt to varying H₂ concentrations is important for understanding competition and survival strategies in energy-limited subseafloor hydrothermal environments. In this study, <i>D. thermolithotrophum</i> showed metabolic adaptations under low H₂ conditions that may provide them with a competitive growth advantage in hydrothermal vent ecosystems when H₂ is limited and other thermophilic hydrogenotrophs, such as methanogens, are also commonly found. This work also demonstrated the dynamic relationship between different types of hydrogenases and how they are coordinated with each other and other key pathways such as CO₂ fixation.