Isolation of haloarchaea that grow at low salinities
Article first published online: 17 MAR 2004
Volume 6, Issue 6, pages 591–595, June 2004
How to Cite
Purdy, K. J., Cresswell-Maynard, T. D., Nedwell, D. B., McGenity, T. J., Grant, W. D., Timmis, K. N. and Embley, T. M. (2004), Isolation of haloarchaea that grow at low salinities. Environmental Microbiology, 6: 591–595. doi: 10.1111/j.1462-2920.2004.00592.x
- Issue published online: 30 MAR 2004
- Article first published online: 17 MAR 2004
- Received 17 September, 2003; revised 1 December, 2003; accepted 10 December, 2003.
Archaea, the third domain of life, were long thought to be limited to environmental extremes. However, the discovery of archaeal 16S rRNA gene sequences in water, sediment and soil samples has called into question the notion of Archaea as obligate extremophiles. Until now, none of these novel Archaea has been brought into culture, a critical step for discovering their ecological roles. We have cultivated three novel halophilic Archaea (haloarchaea) genotypes from sediments in which the pore-water salinity was close to that of sea water. All previously reported haloarchaeal isolates are obligate extreme halophiles requiring at least 9% (w/v) NaCl for growth and are typically the dominant heterotrophic organisms in salt and soda lakes, salt deposits and salterns. Two of these three newly isolated genotypes have lower requirements for salt than previously cultured haloarchaea and are capable of slow growth at sea-water salinity (2.5% w/v NaCl). Our data reveal the existence of Archaea that can grow in non-extreme conditions and of a diverse community of haloarchaea existing in coastal salt marsh sediments. Our findings suggest that the ecological range of these physiologically versatile prokaryotes is much wider than previously supposed.