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Archaeal and bacterial H-GDGTs are abundant in peat and their relative abundance is positively correlated with temperature

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)156-170
Number of pages15
JournalGeochimica et Cosmochimica Acta
Volume227
Early online date2 Mar 2018
DOIs
DateAccepted/In press - 14 Feb 2018
DateE-pub ahead of print - 2 Mar 2018
DatePublished (current) - 15 Apr 2018

Abstract

Glycerol monoalkyl glycerol tetraether lipids (GMGTs; also called ‘H-GDGTs’) differ from the more commonly studied glycerol dialkyl glycerol tetraether (GDGTs) in that they have an additional covalent bond that links the two alkyl chains. Six different archaeal isoprenoidal H-GDGTs (H-isoGDGTs) and one branched H-GDGT (H-brGDGT), presumably produced by bacteria, have previously been found. However, the function of H-GDGTs in both domains of life is unknown. It is thought that the formation of this additional covalent bond results in enhanced membrane stability, accounting for the high abundance of H-GDGTs in extreme environments such as geothermal settings, but so far there has been little evidence to support this hypothesis. Here we report the distribution of H-GDGTs in a global peat database (n = 471) with a broad range in mean annual air temperature (MAAT) and pH. This is the first finding of H-GDGTs in soils (specifically, peat), highlighting that H-GDGTs are widespread in mesophilic settings. In addition, we report the presence of two new H-brGDGTs with one (H-1034) and two (H-1048) additional methyl groups, respectively. Our results suggest that the relative abundance of both bacterial and archaeal H-GDGTs compared to regular GDGTs is related to temperature with the highest relative abundance of H-GDGTs in tropical peats. Although other factors besides temperature likely also play a role, these results do support the hypothesis that H-GDGTs are an adaptation to temperature to maintain membrane stability. The observation that both bacterial and archaeal membrane lipids respond to temperature indicates the same adaption across the lipid divide between these two domains of life, suggesting parallel or convergent evolution (potentially facilitated by lateral gene transfer).

    Research areas

  • Global, GMGT, H-GDGT, Membrane lipid, Peat, Temperature

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    Rights statement: This is the final published version of the article (version of record). It first appeared online via Elsevier at https://www.sciencedirect.com/science/article/pii/S0016703718301078 . Please refer to any applicable terms of use of the publisher.

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    Licence: CC BY

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