Our overarching aim is to draw on expertise from numerous disciplines in order to make a quantum advance in our understanding of life at high salinity, from ecosystems to cellular systems, which in turn will enhance many other areas of science. A flavour of the issues to be discussed is given below.

The role of water

While focussing on halophilic microorganisms, we also aim to investigate commonalities between high salinity as a stressful or extreme condition and other conditions in which water availability is reduced, e.g. desiccation, freezing, high organic solute concentration. At the same time we will dissect the modes of action of different salts on water and biological macromolecules, and in turn examine the responses of microorganisms, drawing on the expertise of physicists specialising in water structure, protein biochemists, physiologists, biochemists, molecular geneticists, and those deriving a whole-cell understanding through functional genomics.

Evolution, taxonomy and systems biology of halophiles

A high quality, robust and predictive taxonomy is a pre-requisite for scientific communication, and we will use this meeting to clarify important taxonomic issues through presentations, discussions, and the joint meeting of the ICSP Subcommittee on the Taxonomy of Halobacteriaceae and the ICSP Subcommittee on the Taxonomy of Halomonadaceae. Genomics provides us with an exciting opportunity to learn about the evolution of halophiles; the evidence for multiple cross-domain gene transfers in extreme halophiles is compelling and likely to be an area of intense discussion at the meeting, particularly in the light of the recent genome analysis of the abundant square haloarchaeon. In addition, a cellular system-level understanding of some halophiles is starting to emerge, providing unique insights into global regulatory networks.

Biogeochemistry, ecology and astrobiology

There is currently great excitement about the presence of salt deposits on Mars and deep-subsurface hypersaline brines on Europa, as well as unusual hypersaline environments on Earth (e.g. deep-sea, hypersaline, anoxic brines in the Mediterranean Sea, polar sea ice, and evaporites that are often more than 1 km thick). It is crucial to ascertain the limits of life on Earth and how hypersalinity influences biogeochemical processes. Thereafter, we will be better placed to look for life and its signatures elsewhere in the solar system. We will address these issues and additionally provide insight into the diversity of halophilic microorganisms from all domains of life.

Adaptation to multiple extremes

Halophilic microorganisms are generally exposed to multiple extremes, and so in this meeting we intend to hold a session on adaptation to high-temperature, alkaline, high-pressure and anoxic hypersaline environments, paying particular attention to the synergistic or antagonistic effects on growth and survival of multiple extremes.

Molecular genetics, biochemistry and biotechnological applications of halophiles

Recent developments describing the intricate workings of halophiles at the subcellular and macromolecular level are not only of fundamental importance, but helping to accelerate the number of potential and realised applications of halophiles, such as novel rhodopsins and the use of enzymes from extreme halophiles in organic solvents. Additionally, the diversity of cultivated and uncultivated extremophiles is being explored to enhance industrial processes (e.g. discovery of unique biocatalysts) and alleviate environmental problems (e.g. biodegradation of vast volumes of oil-polluted production waters).