Dibiphytanyl ether lipids in nonthermophilic crenarchaeotes

Abstract

The kingdom Crenarchaeota is now known to include archaea which inhabit a wide variety of low-temperature environments. We report here lipid analyses of nonthermophilic crenarchaeotes, which revealed the presence of cyclic and acyclic dibiphytanylglycerol tetraether lipids. Nonthermophilic crenarchaeotes appear to be a major biological source of tetraether lipids in marine planktonic environments.

FIG. 1

Evolutionary relationships of uncultivated marine planktonic Archaea (groups I and II) relative to known and cultivated Crenarchaeota and Euryarchaeota. Evolutionary relationships were inferred from 687 unambiguous aligned residues by transversion distance analysis as previously described (5). Numbers appearing at each bifurcation indicate the number of bootstrapped replicates which supported that bifurcation, out of 1,000 bootstrap replicates. pSL12 represents a cloned rRNA fragment recovered from a hot spring microbial community, which appears to be specifically related to the rRNA sequences of marine nonthermophilic crenarchaeotes (1).

FIG. 2

Gas chromatogram of an Antarctic sample which corresponds to the mass spectral analysis shown in Fig. 3, in the region of biphytane elution. Subscripts denote the number of carbon atoms in the biphytane. R, pentacyclic ring; i, isomer.

FIG. 3

Mass spectra of the four identified caldarchaeol derivatives that were common to all samples analyzed. Lipids were extracted, derivatized, and analyzed as described in the text. The mass spectra are derived from the Antarctic picoplankton lipid sample used for the GC trace in Fig. 2. R, pentacyclic ring; i, isomer.

FIG. 4

Caldarchaeol-derived biphytanes from diverse marine samples. Compounds correspond to the structures shown in Fig. 3, as identified by comparison to known standards. Relative abundances of cyclic and acyclic biphytanes in diverse marine samples are shown. The value for most abundant of the four components was arbitrarily set at a relative value of 1. BS, Black Sea sediment; Antarctic, Antarctic picoplankton lipids; C. symbiosum, C. symbiosum lipids; SMB3 and SMB4, Santa Monica Basin suspended particulate lipid samples.