Novel archaeal macrocyclic diether core membrane lipids in a methane-derived carbonate crust from a mud volcano in the Sorokin Trough, NE Black Sea

Alina Stadnitskaia,Michael K Ivanov,Tjeerd C E Van Weering,Jaap S Sinninghe Damsté,Marianne Baas

doi:10.1155/2003/329175

Alina Stadnitskaia, Michael K Ivanov + Show 3 more

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https://doi.org/10.1155/2003/329175

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Abstract

A methane-derived carbonate crust was collected from the recently discovered NIOZ mud volcano in the Sorokin Trough, NE Black Sea during the 11th Training-through-Research cruise of the R/V Professor Logachev. Among several specific bacterial and archaeal membrane lipids present in this crust, two novel macrocyclic diphytanyl glycerol diethers, containing one or two cyclopentane rings, were detected. Their structures were tentatively identified based on the interpretation of mass spectra, comparison with previously reported mass spectral data, and a hydrogenation experiment. This macrocyclic type of archaeal core membrane diether lipid has so far been identified only in the deep-sea hydrothermal vent methanogen Methanococcus jannaschii. Here, we provide the first evidence that these macrocyclic diethers can also contain internal cyclopentane rings. The molecular structure of the novel diethers resembles that of dibiphytanyl tetraethers in which biphytane chains, containing one and two pentacyclic rings, also occur. Such tetraethers were abundant in the crust. Compound-specific isotope measurements revealed delta13C values of -104 to -111/1000 for these new archaeal lipids, indicating that they are derived from methanotrophic archaea acting within anaerobic methane-oxidizing consortia, which subsequently induce authigenic carbonate formation.

Highlights

Geological exploration of the ocean floor has revealed widely occurring fields of submarine fluid discharge, so-called “cold seeps” or “methane seeps,” which create specific structures on the sea floor such as mud volcanoes and pockmarks (Hovland and Judd 1988, Limonov et al 1994, 1997, Ivanov et al 1996a, 1996b)
These lipids are substantially depleted in δ13C, albeit slightly less so than the archaeal lipids, indicating involvement of sulfate-reducing bacteria in the microbial community engaged in anaerobic oxidation of methane (AOM)
Analysis of the polar fraction of the carbonate crust TTR-11 BS-328G-2 by Gas chromatography (GC)–MS revealed a suite of ether lipids diagnostic of the non-thermophilic group of the euryarchaeota and sulfate-reducing bacteria (Figure 2)

Summary

Introduction

Geological exploration of the ocean floor has revealed widely occurring fields of submarine fluid discharge, so-called “cold seeps” or “methane seeps,” which create specific structures on the sea floor such as mud volcanoes and pockmarks (Hovland and Judd 1988, Limonov et al 1994, 1997, Ivanov et al 1996a, 1996b) In these settings, constant and focused fluid supply induces marked biological activity depending on chemosynthetic nutrition (Hovland and Judd 1988, Sibuet et al 1988, Corselli and Basso 1996, Olu et al 1996, 1997, Sibuet and Olu 1998). The best evidence of a consortium of archaea and sulfate-reducing bacteria was obtained by comparison of 16S ribosomal RNA gene sequences and fluorescence in situ hybridization analysis, which showed that methane-oxidizing archaea are phylogenetically associated with the methanogenic orders Methanomicrobiales and Methanosarcinales

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