Temperature influences microbiological growth and catabolic rates. Between 15 and 35 °C the growth rate and cell specific sulfate reduction rate of the sulfate reducing bacterium Desulfococcus multivorans increased with temperature. Sulfur isotope fractionation during sulfate reduction decreased with increasing temperature from 27.2 ‰ at 15 °C to 18.8 ‰ at 35 °C which is consistent with a decreasing reversibility of the metabolic pathway as the catabolic rate increases. Oxygen isotope fractionation, in contrast, decreased between 15 and 25 °C and then increased again between 25 and 35 °C, suggesting increasing reversibility in the first steps of the sulfate reducing pathway at higher temperatures. This points to a decoupling in the reversibility of sulfate reduction between the steps from the uptake of sulfate into the cell to the formation of sulfite, relative to the whole pathway from sulfate to sulfide. This observation is consistent with observations of increasing sulfur isotope fractionation when sulfate reducing bacteria are living near their upper temperature limit. The oxygen isotope decoupling may be a first signal of changing physiology as the bacteria cope with higher temperatures.

中文翻译：

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温度对硫酸盐还原菌（Desulfococcus multivorans）的硫和氧同位素分馏的影响。

温度影响微生物生长和分解代谢率。在 15 至 35 °C 之间，硫酸盐还原细菌 Desulfococcus multivorans 的生长速率和细胞特异性硫酸盐还原速率随温度增加。硫酸盐还原过程中的硫同位素分馏随着温度从 15 °C 时的 27.2 ‰ 增加到 35 °C 时的 18.8 ‰ 而降低，这与代谢途径的可逆性随着分解代谢率的增加而降低是一致的。相比之下，氧同位素分馏在 15 至 25 °C 之间降低，然后在 25 至 35 °C 之间再次增加，这表明在较高温度下硫酸盐还原途径的第一步中的可逆性增加。这表明相对于从硫酸盐到硫化物的整个途径，从硫酸盐进入细胞到形成亚硫酸盐的步骤之间硫酸盐还原的可逆性脱钩。该观察结果与当硫酸盐还原细菌生活在其温度上限附近时增加的硫同位素分馏的观察结果一致。随着细菌应对更高的温度，氧同位素解耦可能是改变生理机能的第一个信号。