Intact Polar and Core Glycerol Dibiphytanyl Glycerol Tetraether Lipids of Group I.1a and I.1b Thaumarchaeota in Soil

Abstract

<jats:title>ABSTRACT</jats:title><jats:p>Ecological studies of thaumarchaeota often apply glycerol dibiphytanyl glycerol tetraether (GDGT)-based intact membrane lipids. However, these components have only been characterized for thaumarchaeota from aquatic environments. Thaumarchaeota have been shown to play an important role in the nitrogen cycle in soil as ammonium oxidizers, and GDGTs are common lipids encountered in soil. We report the core and intact polar lipid (IPL) GDGTs produced by three newly available thaumarchaeota isolated from grassland soil in Austria (“<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Nitrososphaera viennensis</jats:named-content>,” group I.1b) and enriched from agricultural soils in South Korea (“<jats:italic>Candidatus</jats:italic>Nitrosoarchaeum koreensis” MY1, group I.1a; and “<jats:italic>Candidatus</jats:italic>Nitrososphaera” strain JG1, group I.1b). The soil thaumarchaeota all synthesize crenarchaeol as their major core GDGT, in agreement with the fact that crenarchaeol has also been detected in thaumarchaeota from aquatic environments. The crenarchaeol regioisomer apparently is produced in significant quantities only by soil thaumarchaeota of the I.1b subgroup. In addition, GDGTs with 0 to 4 cyclopentane moieties and GDGTs containing an additional hydroxyl group were detected. The IPL head groups of their membrane lipids comprised mainly monohexose, dihexose, trihexose, phosphohexose, and hexose-phosphohexose moieties. The hexose-phosphohexose head group bound to crenarchaeol occurred in all soil thaumarchaeota, and this IPL is at present the only lipid that is detected in all thaumarchaeota analyzed so far. This specificity and its lability indicate that it is the most suitable biomarker lipid to trace living thaumarchaeota. This study, in combination with previous studies, also suggests that hydroxylated GDGTs occur in the I.1a, but not in the I.1b, subgroup of the thaumarchaeota.</jats:p>

Differential degradation of intact polar and core glycerol dialkyl glycerol tetraether lipids upon post-depositional oxidation

“…Other IPLs might have been present in minor amounts in the IPL fraction, but the similarity of the (Table 2), with a weighted average value of 0.64. This is consistent with results from thaumarchaeal cultures, which showed that MH GDGTs and HPH GDGTs had a greater contribution from GDGT-1, while DH GDGTs consisted mainly of GDGT-2, -3 and -4 Pitcher et al, 2011b;Sinninghe Damsté et al, 2012). Considering the substantial differences in TEX 86 values from MH GDGTs and DH GDGTs (0.15), the proportional decrease in DH GDGTs vs. MH GDGTs in the oxidized part of the turbidite ( Fig.…”

“…Analysis of the unoxidized sediment showed the presence of two main intact polar lipid species, MH crenarchaeol and DH crenarchaeol, while no HPH crenarchaeol was detected. This distribution is different from the distribution in cultures, where HPH crenarchaeol is always present Pitcher et al, 2010;Pitcher et al, 2011b;Sinninghe Damsté et al, 2012) but is similar to that of IPLs in deeper marine sediments (Biddle et al, 2006;Lipp and Hinrichs, 2009). The absence of HPH crenarchaeol is probably due to the greater lability of this IPL GDGT, as shown for Arabian Sea sediments, where degradation at the surface occurred within a few cm (Lengger et al, 2012b).…”

“…However, it would also imply that these sedimentary Thaumarchaeota would only produce MH crenarchaeol and no substantial amounts of DH and HPH crenarchaeol. This seems unlikely as sedimentary and soil Thaumarchaeota in enrichment cultures (Pitcher et al, 2011b;Sinninghe Damsté et al, 2012) and in surface sediments (Lengger et al, 2012) do synthesize GDGTs with MH , DH and HPH head groups. Alternatively, part of the MH crenarchaeol, and, to a minor extent, DH crenarchaeol, could also stem from a terrestrial source, resulting in enhanced preservation as discussed above for the brGDGTs.…”

Nitrososphaera viennensis gen. nov., sp. nov., an aerobic and mesophilic, ammonia-oxidizing archaeon from soil and a member of the archaeal phylum Thaumarchaeota

“…Crenarchaeol and its regioisomer, both GDGTs with one cyclohexane and four cyclopentane rings (Sinninghe Damsté et al , 2002), were the major core lipids (80 %; Sinninghe Damsté et al , 2012). So far, crenarchaeol has been found exclusively in members of the Thaumarchaeota .…”

A Mesophilic, Autotrophic, Ammonia-Oxidizing Archaeon of Thaumarchaeal Group I.1a Cultivated from a Deep Oligotrophic Soil Horizon

“…Strain MY2 produces two major GDGTs: GDGT-0 (GDGT with no internal rings; 24.8% of total GDGTs) and crenarchaeol (28.4%). Both GDGTs are produced by AOA, including those enriched from soils (53,54). During the […”