Chemotrophic microorganisms gain energy for cellular functions by catalyzing oxidation–reduction (redox) reactions that are out of equilibrium. Calculations of the Gibbs energy ( ΔG _r ) can identify whether a reaction is thermodynamically favourable and quantify the accompanying energy yield at the temperature, pressure and chemical composition in the system of interest. Based on carefully calculated values of ΔG _r , we predict a novel microbial metabolism – sulfur comproportionation (3H₂S + + 2H⁺ ⇌ 4S⁰ + 4H₂O). We show that at elevated concentrations of sulfide and sulfate in acidic environments over a broad temperature range, this putative metabolism can be exergonic ( ΔG _r <0), yielding ~30–50 kJ mol⁻¹. We suggest that this may be sufficient energy to support a chemolithotrophic metabolism currently missing from the literature. Other versions of this metabolism, comproportionation to thiosulfate (H₂S + ⇌ + H₂O) and to sulfite (H₂S + 3 ⇌ 4 + 2H⁺), are only moderately exergonic or endergonic even at ideal geochemical conditions. Natural and impacted environments, including sulfidic karst systems, shallow‐sea hydrothermal vents, sites of acid mine drainage, and acid–sulfate crater lakes, may be ideal hunting grounds for finding microbial sulfur comproportionators.

中文翻译：

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自然界中缺少的另一种化营养营养代谢：硫代入。

化学营养型微生物通过催化不平衡的氧化还原（redox）反应获得细胞功能所需的能量。吉布斯能量（计算的ΔG _[R ）可以识别一个反应是否是热力学上有利和量化在感兴趣的系统中的温度，压力和化学成分伴随能量产率。基于仔细计算值ΔG _[R ，我们预测的新的微生物代谢-硫歧化（3H ₂ S + + 2H ⁺ ⇌ 4S ⁰ + 4H ₂ O）。我们表明，在升高的浓度的硫化物和硫酸盐的在酸性环境中在宽的温度范围内，该假定代谢可以是放能（ΔG _[R <0），产生〜30-50千焦摩尔^-1。我们建议这可能是足够的能量来支持目前文献中缺少的化学营养型代谢。这种代谢的其它版本，歧化以硫代硫酸盐（H ₂ S + ⇌ + H ₂ O）和亚硫酸盐（H ₂ S + 3 ⇌ 4 + 2H ⁺ ），即使在理想的地球化学条件下也仅是中等强度的或中等强度的。自然和受冲击的环境，包括硫化岩溶系统，浅海热液喷口，酸性矿山排水场所和酸性硫酸盐火山口湖，可能是寻找微生物硫代比剂的理想狩猎场。