Pellerin André, Antler Gilad, Marietou Angeliki, Turchyn Alexandra V, Jørgensen Bo Barker
Center for Geomicrobiology, Ny Munkegade 116, Aarhus C 8000, Aarhus University, Department of Bioscience, Denmark.
Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, P. O. Box 653, Beer-Sheva 84105, Israel.
FEMS Microbiol Lett. 2020 May 1;367(9). doi: 10.1093/femsle/fnaa061.
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.
温度会影响微生物的生长和分解代谢速率。在15至35摄氏度之间，硫酸盐还原菌多噬脱硫球菌的生长速率和细胞特定硫酸盐还原速率随温度升高而增加。硫酸盐还原过程中的硫同位素分馏随着温度升高而降低，从15摄氏度时的27.2‰降至35摄氏度时的18.8‰，这与随着分解代谢速率增加，代谢途径的可逆性降低是一致的。相比之下，氧同位素分馏在15至25摄氏度之间降低，然后在25至35摄氏度之间再次升高，这表明在较高温度下硫酸盐还原途径的第一步中可逆性增加。这表明从硫酸盐摄入细胞到亚硫酸盐形成的步骤中，硫酸盐还原的可逆性与从硫酸盐到硫化物的整个途径相比出现了解耦。这一观察结果与当硫酸盐还原细菌在接近其温度上限时硫同位素分馏增加的观察结果一致。氧同位素解耦可能是细菌应对更高温度时生理变化的首个信号。
