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 (1, 2, 3), Marianne Baas (2), Michael K. Ivanov (1), Tjeerd C. E. Van Weering (2) and Jaap S. Sinninghe Damsté (2)
1. UNESCO-MSU Center for Marine Geosciences, Moscow State University, Faculty of Geology, Vorobijevi Gory 1, 119899 Moscow, Russia / 2. Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, The Netherlands / 3. Author to whom correspondence should be addressed ([email protected]) / Received July 11, 2002; accepted September 18, 2002; published online October 17, 2002
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 δ13C values of –104 to –111‰ 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.
Keywords: anaerobic oxidation of methane, archaeal membrane lipids, fluid venting, microbial processes.