Dual stable isotope probing has been used to infer rates of microbial biomass production and modes of carbon fixation. In order to validate this approach for assessing archaeal production, the methanogenic archaeon Methanosarcina barkeri was grown either with H₂, acetate or methanol with D₂O and ¹³C‐dissolved inorganic carbon (DIC). Our results revealed unexpectedly low D incorporation into lipids, with the net fraction of water‐derived hydrogen amounting to 0.357 ± 0.042, 0.226 ± 0.003 and 0.393 ± 0.029 for growth on H₂/CO₂, acetate and methanol respectively. The variability in net water H assimilation into lipids during the growth of M. barkeri on different substrates is possibly attributed to different Gibbs free energy yields, such that higher energy yield promoted the exchange of hydrogen between medium water and lipids. Because NADPH likely serves as the portal for H transfer, increased NADPH production and/or turnover associated with high energy yield may explain the apparent differences in net water H assimilation into lipids. The variable DIC and water H incorporation into M. barkeri lipids imply systematic, metabolic patterns of isotope incorporation and suggest that the ratio of ¹³C‐DIC versus D₂O assimilation in environmental samples may serve as a proxy for microbial energetics in addition to microbial production and carbon assimilation pathways.

中文翻译：

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碳和氢的底物依赖性掺入，用于巴氏甲烷八叠球菌的脂质生物合成。

双重稳定同位素探测已用于推断微生物生物量的产生速率和碳固定模式。为了验证这种评估古细菌产量的方法，将产甲烷的古细菌甲烷单孢菌生长于H ₂，乙酸盐或甲醇，D ₂ O和¹³ C溶解的无机碳（DIC）中。我们的结果显示，脂质中D的掺入量出乎意料地低，在H ₂ / CO ₂，乙酸盐和甲醇中生长的水衍生氢的净分数分别为0.357±0.042、0.226±0.003和0.393±0.029 。M生长过程中净水H同化到脂质的变化。不同底物上的巴克利可能归因于吉布斯自由能的不同产生，因此更高的能量产生促进了中水与脂质之间的氢交换。由于NADPH可能充当H转移的门户，因此增加的NADPH产量和/或与高能量产率相关的周转率可以解释净水H同化为脂质的表观差异。变量DIC和水H掺入M中。Barkeri脂质暗示同位素掺入的系统代谢模式，并表明¹³ C‐DIC与D ₂的比率除了微生物产生和碳同化途径外，环境样品中的O同化作用还可以作为微生物能量学的替代物。