Temperature and pH control on lipid composition of silica sinters from diverse hot springs in the Taupo Volcanic Zone, New Zealand

Kaur, Gurpreet; Mountain, Bruce W.; Stott, Matthew B.; Hopmans, Ellen C.; Pancost, Richard D.

doi:10.1007/s00792-014-0719-9

Cited by 30 publications

(44 citation statements)

References 73 publications

(151 reference statements)

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“…In the current study, therefore, we explore the lipid distributions in both the soluble and IOM of TVZ hot spring silica sinters. This work complements previous investigations on the distribution of prokaryotic membrane lipids in the TVZ, which focused strictly on the solvent‐extractable OM fractions and their geochemical implications (Kaur, Mountain, Hopmans, & Pancost, , ; Kaur et al., ; Kaur, Mountain, Stott, Hopmans, & Pancost, ; Pancost et al., ). In particular, we focus on the prokaryotic biomarkers that occur in the IOM fractions and explore which biomarkers and associated organisms might be more prone to preservation.…”

Section: Introductionsupporting

confidence: 70%

“…The average chain length (ACL) of the DAGEs differs amongst the two sinters (Figure b; see also Kaur et al., ). The dominant DAGEs in CP1 contain alkyl moieties in combinations of C 16 /C 17 , C 17 /C 17 and C 18 /C 18 , resulting in an ACL of around 17.1.…”

Section: Resultsmentioning

confidence: 86%

“…Intriguingly, n ‐alkanes are observed in solvent‐extractable fractions, but also in insoluble fractions, consistent with previous investigations (e.g., Amblès, Grasset, Dupas, & Jacquesy, ). A thorough analysis of the solvent‐extracted lipid biomarkers, including FAs, hopanoids, DAGEs, archaeol and i‐GDGTs, that occur in these geothermal settings has been reported elsewhere (Kaur, ; Kaur et al., , , , ). Those papers generally focused on the neutral fractions, that is the free lipid biomarkers rather than the IP lipids, such that a direct comparison to this work, where all solvent‐extractable lipids will have been released via AMe of total lipid extracts (TLEs), is not appropriate.…”

Section: Resultsmentioning

confidence: 95%

“…The OM content of all three samples is very low—TOC contents are typically less than 1% (Table )—and almost exclusively derived from prokaryotic sources; for further site and sample details see Kaur et al. (, , , ).…”

Section: Methodsmentioning

confidence: 92%

“…Lipid biomarkers encountered in TVZ silica sinters have been comprehensively detailed previously (Kaur et al., , , ), and their sources tentatively attributed to a wide range of hyperthermophilic bacteria (e.g., the order Aquificales and some species such as Ammonifex degensii , Thermodesulfobacterioum commune , Clostridium thermosulfurogenes ) and hyperthermophilic archaea (e.g., the orders of Sulfolobales, Thermoproteales and Thermoplastales) (Kaur et al., , , ; and references therein). Here, we focus on the comparison of prokaryotic membrane lipids obtained from solvent extraction, BD and Sox, versus the analogues in IOM fractions, BHy and AMe.…”

Section: Discussionmentioning

confidence: 99%

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Selective chemical degradation of silica sinters of the Taupo Volcanic Zone (New Zealand). Implications for early Earth and Astrobiology

et al. 2019

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Most organic matter (OM) on Earth occurs as kerogen‐like materials, that is naturally formed macromolecules insoluble with standard organic solvents. The formation of this insoluble organic matter (IOM) is a topic of much interest, especially when it limits the detection of compounds of geomicrobiological interest. For example, studies that search for biomarker evidence of life on early Earth or other planets usually use solvent‐based extractions. This leaves behind a pool of OM as unexplored post‐extraction residues, potentially containing diagnostic biomarkers. Since the IOM has an enhanced potential for preservation compared to soluble OM, analysing IOM‐released biomarkers can also provide even deeper insights into the ecology of ancient settings, with implications for early Earth and Astrobiology investigations. Here, we analyse the prokaryotic lipid biosignature within soluble and IOM of the Taupo Volcanic Zone (TVZ) silica sinters, which are key analogues in the search for life. We apply sequential solvent extractions and a selective chemical degradation upon the post‐solvent extraction residue. Moreover, we compare the IOM from TVZ sinters to analogous studies on peat and marine sediments to assess patterns in OM insolubilisation across the geosphere. Consistent with previous work, we find significant but variable proportions—1%–45% of the total prokaryotic lipids recovered—associated with IOM fractions. This occurs even in recently formed silica sinters, likely indicating inherent cell insolubility. Moreover, archaeal lipids seem more prone to insolubilisation as compared to the bacterial analogues, which might enhance their preservation and also bias overall biomarkers interpretation. These observations are similar to those observed in other settings, confirming that even in a setting where the OM derives predominantly from prokaryotic sources, patterns of IOM formation/occurrence are conserved. Differences with other settings, however, such as the occurrence of archaeol in IOM fractions, could be indicative of different mechanisms for IOM formation that merit further exploration.

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