Dunaliella Cells in Fluid Inclusions in Halite: Significance for Long-term Survival of Prokaryotes

Abstract

A 90-m-long (100,000 year old) salt core from Death Valley, California, contains cells of the algal genus Dunaliella co-trapped with prokaryote cells in fluid inclusions in halite. It is hypothesized that Dunaliella cells provided glycerol, the carbon source needed by halophilic Archaea for survival over periods of tens of thousands of years. Support for this hypothesis includes: observations that intracellular materials leaked from Dunaliella cells into fluid inclusions; the distribution of Dunaliella cells in the Death Valley core, which matches the distribution of culturable prokaryotic cells; and halophilic Archaea cultured from the Death Valley core grew in media containing glycerol as the only carbon source.

Keywords:

• β-carotene
• Dunaliella
• Death Valley
• fluid inclusions
• glycerol
• halite
• Saline Valley
• survival

This project was supported by the National Science Foundation Biogeoscience Grant EAR-0433802.

Notes

^a + = Dunaliella cells or prokaryotes observed in fluid inclusions in halite from this depth; − = Dunaliella cells or prokaryotes not observed in fluid inclusions in halite from this depth. Data for prokaryotes from Schubert et al. (2009 and in review).

^b + = one strain cultured from this depth; ++ = two strains cultured from this depth; ++++ = four strains cultured from this depth; − = zero strains cultured from this depth. Data from Schubert et al. (in review) except where noted.

^c Vreeland et al. (2007).

^d Mormile et al. (2003).

^a GB medium is modified after PGB medium (Schubert et al. in review).