Microorganisms regulate the composition of their membranes in response to environmental cues. Many Archaea maintain the fluidity and permeability of their membranes by adjusting the number of cyclic moieties within the cores of their glycerol dibiphytanyl glycerol tetraether (GDGT) lipids. Cyclized GDGTs increase membrane packing and stability, which has been shown to help cells survive shifts in temperature and pH. However, the extent of this cyclization also varies with growth phase and electron acceptor or donor limitation. These observations indicate a relationship between energy metabolism and membrane composition. Here we show that the average degree of GDGT cyclization increases with doubling time in continuous cultures of the thermoacidophile Sulfolobus acidocaldarius (DSM 639). This is consistent with the behavior of a mesoneutrophile, Nitrosopumilus maritimus SCM1. Together, these results demonstrate that archaeal GDGT distributions can shift in response to electron donor flux and energy availability, independent of pH or temperature. Paleoenvironmental reconstructions based on GDGTs thus capture the energy available to microbes, which encompasses fluctuations in temperature and pH, as well as electron donor and acceptor availability. The ability of Archaea to adjust membrane composition and packing may be an important strategy that enables survival during episodes of energy stress.

中文翻译：

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能量通量控制嗜酸小球藻中的四醚脂质环化。

微生物根据环境提示调节其膜的组成。许多古细菌通过调节其甘油二双植烷酰基甘油四醚（GDGT）脂质核心中的环状部分的数量来维持其膜的流动性和渗透性。环化的GDGT可增加膜的堆积和稳定性，这已被证明可以帮助细胞在温度和pH的变化中生存。但是，这种环化的程度也随生长期和电子受体或供体的限制而变化。这些观察结果表明能量代谢与膜组成之间的关系。在这里，我们显示了在嗜热嗜酸菌Sulfolobus acidocaldarius（DSM 639）的连续培养中，GDGT环化的平均程度随时间加倍而增加。这与中性粒细胞的行为是一致的，海豚鱼（Nitrosopumilus maritimus）SCM1。总之，这些结果表明，古细菌的GDGT分布可以响应电子给体通量和能量可用性而发生变化，而与pH或温度无关。因此，基于GDGT的古环境重建捕获了微生物可用的能量，其中包括温度和pH的波动以及电子供体和受体的可用性。古细菌调节膜组成和堆积的能力可能是一种重要的策略，可在能量应激发作期间生存。其中包括温度和pH值的波动，以及电子给体和受体的可用性。古细菌调节膜组成和堆积的能力可能是一种重要的策略，可在能量应激发作期间生存。其中包括温度和pH值的波动，以及电子给体和受体的可用性。古细菌调节膜组成和堆积的能力可能是一种重要的策略，可在能量应激发作期间生存。