Abstract Lake Vida, located in a closed basin in the McMurdo Dry Valleys, East Antarctica, permanently encapsulates an interstitial anoxic, aphotic, cold (−13 °C), brine ecosystem within 27+ m of ice. Metabolically active, but cold-limited, slow-growing bacteria were detected in the brine. Lake Vida brine is derived from the evaporation of a body of water that occupied the same basin prior to ∼2800 years ago. The characteristics of this body of water changed over time and, at one point, likely resembled other modern well-studied perennial ice-covered lakes of the Dry Valleys. We characterized the dichloromethane-extractable fraction of the environmental metabolome of Lake Vida brine in order to constrain current and ancient biogeochemical processes. Analysis of the dichloromethane-extract of Lake Vida brine by gas chromatography-mass spectrometry and comprehensive multidimensional gas chromatography-time of flight-mass spectrometry reveals the presence of legacy compounds (i.e. diagenetic products of chlorophylls and carotenoids) deriving from photosynthetic algae and anaerobic, anoxygenic photosynthetic bacteria. This legacy component dilutes the environmental signal of metabolites deriving from the extant bacterial community. The persistence of legacy metabolites (paleometabolites), apparent in Lake Vida brine, is a result of the slow turnover rates of the extant bacterial population due to low metabolic activities caused by the cold limitation. Such paleometabolites may also be preserved in other cold-limited or nutrient-depleted slow-growing ecosystems. When analyzing ecosystems with low metabolic rates, the presence of legacy metabolites must first be addressed in order to confidently recognize and interpret the environmental metabolome of the extant ecosystem.

中文翻译：

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来自先前生态系统的遗留代谢物对东南极洲维达湖盐水环境代谢组学的影响

摘要 维达湖位于南极洲东部麦克默多干谷的一个封闭盆地中，在 27 米以上的冰层内永久封装了一个间隙缺氧、无光、寒冷 (-13 °C) 的盐水生态系统。在盐水中检测到代谢活跃但受冷限制的生长缓慢的细菌。维达湖的卤水来源于大约 2800 年前占据同一盆地的水体的蒸发。这片水域的特征随着时间的推移而发生变化，在某一点上，它可能类似于干谷的其他经过充分研究的现代多年生冰覆盖的湖泊。我们表征了维达湖盐水环境代谢组的二氯甲烷可提取部分，以限制当前和古老的生物地球化学过程。通过气相色谱-质谱法和综合多维气相色谱-飞行时间-质谱法对维达湖盐水的二氯甲烷提取物进行分析，表明存在来自光合藻类和厌氧菌的遗留化合物（即叶绿素和类胡萝卜素的成岩产物），无氧光合细菌。这种遗留成分稀释了来自现存细菌群落的代谢物的环境信号。遗留代谢物（古代谢物）在维达湖盐水中明显存在，这是由于低温限制导致的低代谢活动导致现存细菌种群更新率缓慢的结果。这种古代谢物也可能保存在其他寒冷受限或营养耗尽的缓慢生长的生态系统中。