All life requires energy to drive metabolic reactions such as growth and cell maintenance; therefore, fluctuations in energy availability can alter microbial activity. There is a gap in our knowledge concerning how energy availability affects the growth of extreme chemolithoautotrophs. Toward this end, we investigated the growth of thermoacidophile Acidianus ambivalens during sulfur oxidation under aerobic to microaerophilic conditions. Calorimetry was used to measure enthalpy (ΔH_inc) of microbial activity, and chemical changes in growth media were measured to calculate Gibbs energy change (ΔG_inc) during incubation. In all experiments, Gibbs energy was primarily dissipated through the release of heat, which suggests enthalpy‐driven growth. In microaerophilic conditions, growth was significantly more efficient in terms of biomass yield (defined as C‐mol biomass per mole sulfur consumed) and resulted in lower ΔG_inc and ΔH_inc. ΔG_inc in oxygen‐limited (OL) and oxygen‐ and CO₂‐limited (OCL) microaerophilic growth conditions resulted in averages of −1.44 × 10³ kJ/C‐mol and −7.56 × 10² kJ/C‐mol, respectively, and average ΔH_inc values of −1.11 × 10⁵ kJ/C‐mol and −4.43 × 10⁴ kJ/C‐mol, respectively. High‐oxygen experiments resulted in lower biomass yield values, an increase in ΔG_inc to −1.71 × 10⁴ kJ/C‐mol, and more exothermic ΔH_inc values of −4.71 × 10⁵ kJ/C‐mol. The observed inefficiency in high‐oxygen conditions may suggest larger maintenance energy demands due to oxidative stresses and a preference for growth in microaerophilic environments.

中文翻译：

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Acidianus ambivalens的能量增长对氧气可用性的响应。

所有生命都需要能量来驱动新陈代谢反应，例如生长和细胞维持。因此，能量利用率的波动会改变微生物的活动。关于能量的利用如何影响极端的化石自养生物的增长，我们的知识还存在空白。为此，我们研究了在需氧至微需氧条件下硫氧化过程中嗜热嗜酸性嗜酸性嗜酸性酸菌的生长。量热法用于测量微生物活性的焓（ΔH _inc），并测量生长介质中的化学变化以计算吉布斯能量变化（ΔG _inc）。在所有实验中，吉布斯能量主要是通过释放热量来消散的，这表明由焓驱动的增长。在微需氧条件下，就生物量产量而言（定义为每摩尔硫消耗的C-mol生物量），生长效率显着提高，并导致较低的ΔG _inc和ΔH _inc。Δ ģ _INC在氧受限（OL）和氧-和CO ₂ -有限（OCL）微需氧生长条件导致的-1.44×10平均³ 千焦耳/ C-mol和-7.56×10 ² 千焦耳/ C摩尔，平均ΔH _inc值分别为-1.11×10 ⁵  kJ / C-mol和-4.43×10^分别为4  kJ / C-mol。高氧实验导致较低的生物量产率值，ΔG _inc增至-1.71×10 ⁴  kJ / C-mol，以及更多的放热ΔH _inc值为-4.71×10 ⁵  kJ / C-mol。在高氧条件下观察到的效率低下，可能由于氧化应激和微需氧环境下的生长偏好而导致维护能量需求量更大。