Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published September 2008 | metadata_only
Journal Article

Lipid biomarker and phylogenetic analyses to reveal archaeal biodiversity and distribution in hypersaline microbial mat and underlying sediment


This study has utilized the tools of lipid biomarker chemistry and molecular phylogenetic analyses to assess the archaeal contribution to diversity and abundance within a microbial mat and underlying sediment from a hypersaline lagoon in Baja California. Based on abundance of ether-linked isoprenoids, archaea made up from 1 to 4% of the cell numbers throughout the upper 100 mm of mat and sediment core. Below this depth archaeal lipid was two times more abundant than bacterial. Archaeol was the primary archaeal lipid in all layers. Relatively small amounts of caldarchaeol (dibiphytanyl glyceroltetraether) were present at most depths with phytanyl to biphytanyl molar ratios lowest (~10 : 1) in the 4–17 mm and 100–130 mm horizons, and highest (132 : 1) in the surface 0–2 mm. Lipids with cyclic biphytanyl cores were only detected below 100 mm. A novel polar lipid containing a C30 isoprenoid (squalane) moiety was isolated from the upper anoxic portion of the core and partially characterized. Hydrocarbon biomarker lipids included pentamethylicosane (2–10 mm) and crocetane (primarily below 10 mm). Archaeal molecular diversity varied somewhat with depth. With the exception of samples at 0–2 mm and 35–65 mm, Thermoplasmatales of marine benthic group D dominated clone libraries. A significant number of phylotypes representing the Crenarchaeota from marine benthic group B were generally present below 17 mm and dominated the 35–65 mm sample. Halobacteriaceae family made up 80% of the clone library of the surface 2 mm, and consisted primarily of sequences affiliated with the haloalkaliphilic Natronomonas pharaonis.

Additional Information

© 2008 Blackwell Publishing Ltd. Received 28 December 2007; accepted 9 May 2008; published Online 28 June 2008; in print September 2008. We thank the Exportadora de Sal, S.A., for permission to work in their facility and for technical assistance. We thank the Mexican government for permission to carry out research at Guererro Negro, Baja California Sur. We thank three anonymous reviewers for their efforts and valuable comments. We thank Yanek Hebting for suggesting improvements to the ether cleavage methodology. We thank Robert Vrijenhoek (MBARI) and Ed DeLong for generous use of the sequencing facilities. Victoria Orphan was supported by an NRC postdoctoral fellowship and by a grant from the Moore Foundation. Linda Jahnke and David Des Marais were supported by the NASA Exobiology Program and the NASA Astrobiology Institute. Roger Summons was supported by the NSF and the NASA Exobiology Program.

Additional details

August 22, 2023
August 22, 2023