2) What gene products

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Haloarchaea are so adapted to high-salt environments that they cannot survive in low-salt conditions. There are 6 different haloarchaeal genomes that have been sequenced, which would allow us to compare genetic systems.

Haloarchaea balance a high-salt environment by having at least an equally high intracellular salt concentration usually of KCl. Due to changes in weather and other environmental conditions, haloarchaea must be osmoadaptive over a larger range of salt concentrations. (Soppa 2006) Halophilic proteins are adapted to high-salt by having more acidic residues than basic residues, or a high concentration of negative charges on the outside of the folded protein in order to attract hydrated cations. (See an abstract about the biochemistry of this) The cell membrane is also charged with acidic lipids to maintain structure.

Although Haloarchaea require high salt concentrations for growth, this high salt concentration in their environment limits the availability of oxygen for respiration. (Wikipedia) They are generally aerobic species, so this would be an interesting dynamic to explore. There is a significant amount of observations on microbial survival in high salt concentrations, but the mechanisms aren't fully understood.

See this article Microbial life at high salt concentrations: phylogenetic and metabolic diversity
Also found a good article on bioenergetics in halophiles: Gonzalez 2009

Questions to keep exploring:

  • Does H. mukohataei use compatible solutes (K+) to maintain structure in high salt or another method
  • How are different metabolic pathways (light, respiration) regulated in a possibly low-oxygen environment
  • Are H. mukohataei genes different from other extreme halophiles? are acidic residues conserved?