Microorganisms are found everywhere, even under the most extreme environmental conditions. These include extremely high temperature environments in which growth of certain Archaea – the most primitive forms of life – is possible at temperatures up to 110oC or higher, and hypersaline environments saturated with salt.

The deep-sea hydrothermal vents present a fascinating environment for the study of life at high temperature. Stable temperature gradients exist ranging from over 350oC to ambient seawater temperature, and diverse groups of thermophiles and hyperthermophiles find their niche in such gradients. With the help of manned and unmanned submersibles such hydrothermal vents can be sampled, and a great variety of novel thermophilic microorganisms has already been isolated from them. Thermophilic representatives of both the archaeal and the bacterial domain have been found there, and some of the hyperthermophiles are already being exploited as the source of thermophilic enzymes.

Novel discoveries on the microbiology of the hydrothermal vents will be highlighted in two talks at the FEMS Congress of European Microbiologists at Ljubljana, Slovenia, June 29th. – July 3rd.; one on the archaeal types (Christian Jeanthon and colleagues) and one on anaerobic moderate thermophiles (to be presented by Elizaveta Bonch-Osmolovskaia).

Notes for editor

Halophilic microorganisms able to grow at salt concentrations at or approaching saturation are known for many decades. Halophiles are found in all three domains of life: Archaea, Bacteria and Eukarya. A few halophiles have been investigated in depth and have become laboratory models for the study of the adaptation of microorganisms to life at high salt concentrations. These include the archaeon Halobacterium salinarum, the bacterium Halomonas elongata, and the eukaryotic unicellular alga Dunaliella. The talks in this symposium will show that the world of halophilic microorganisms is much more varied. The variety of Archaea inhabiting high-salt environments is much larger than known before (a topic to be highlighted by Terry McGenity and coworkers), while halophilic fungi now appear to be much more important contributors to the microbial biomass and activity in hypersaline ecosystems than was estimated in the past (as documented by Nina Gunde-Cimerman). In addition, a variety of halophilic methane- and other one-carbon compound oxidizing bacteria have been discovered by the group of Yuri Trotsenko. Moreover, it was recently found that not all extremely halophilic aerobic red heterotrophs that live in salt-saturated environments are necessarily archaeal: Salinibacter is a member of the Bacteria, but shares many properties with the extremely halophilic Archaea of the family Halobacteriaceae (to be presented by Aharon Oren).

Thermophilic and halophilic microorganisms form highly diverse groups, and the symposium will provide an up-to-date account of our current understanding of biodiversity at the extremes of temperature and salt concentration.


For more information: http://www.fems-microbiology.org/congress2003.htm