Brine pool
[3] The brine often contains high concentrations of hydrogen sulfide and methane, which provide energy to chemosynthetic organisms that live near the pool.
Depending on concentration, some minerals such as baryte (barium sulfate) precipitate out of the brine and form crystalline crusts around the edge of the pool.
[8] Patchy, reddish layers can be observed floating above the dense brine interface due to high densities of halophilic archaea that are supported by these environments.
[9] These shores are complex environments with significant shifts in salinity, oxygen concentration, pH, and temperature over a relatively small vertical scale.
When an organism enters a brine pool, it attempts to "breathe" the environment and experiences cerebral hypoxia due to the lack of oxygen and toxic shock from the hypersalinity.
[8] Despite the harsh conditions, life in the form of macrofauna such as bivalves can be found in a thin area along the rim of a brine pool.
A novel genus and species of bivalves, known as Apachecorbula muriatica, has been found along the edge of the "Valdivia Deep" brine pool in the Red Sea.
Microbes help support the larger biological community around environments like brine pools and are key to understanding the survival of other extremophiles.
The research into the growth and function of artificial extremophile biofilms has been slow due to the difficulty in recreating the extreme deep-sea environments they are found in.
[22] Common procedures for characterizing marine microbial communities by metagenomic analysis includes sampling, filtration and extraction, DNA sequencing, and comparison to databases.
[citation needed] The taxonomic makeup of the main microbial communities found at Atlantis II and Discovery without including minor or unknown species to avoid ambiguity is summarized in the following list that is based on the data from primary articles.
[26] Brine pools also exert ionic, kosmotropic, and chaotropic effects on the cells, which also causes additional challenges for the organisms to survive these extreme environments.
In order to decrease the risk of chaotropic effects on the cells, halophilic archaea have a "salt-in" approach and "compatible-solute" strategy, which increases intracellular ionic concentration (mostly K+) to decrease the osmotic pressure; thus, these organisms have adapted their entire metabolic machinery to maintain salt concentration inside of their cells.
[30] In some brine pools, high water temperatures and hydrostatic pressures result in piezophilic microorganisms that synthesize thermoprotective molecules (e.g. hydroxyketone) to prevent the denaturation of proteins and decrease the risk of desiccation.
[31][32][33][34] Another important adaptation is the use of alternative electron acceptors to yield energy, such as iron, manganese,[35] sulfate, elemental sulfur,[36] carbon dioxide, nitrite, and nitrate.
[55] In addition, some novel groups have been isolated from saline lakes which can anaerobically respire sulfur using acetate, pyruvate, formate, or hydrogen as a sole electron donors.
[56] There is a high concentration of bacteria present in brine pools that serve essential roles for the ecosystem, such as being part of symbiotic relationships or acting as a food source for several organisms in this habitat.
Examples include tubeworms and clams having a symbiotic relationship with many of these bacteria to convert chemical energy from hydrogen sulfide, and in exchange providing them food to allow reproduction and development;[57] or mussels providing a safe habitat for bacteria that feed on methane while thriving due to the chemosynthetic, carbon-fixing symbionts that are inhabiting their gill tissues.
[59] Bacteria can also act as epibiotic symbiont, which were found to play an important role in the adaptations of microorganisms to these environments, such as organisms from the flagellated group Euglenozoa that have been thriving in brine pools due to this relationship.
[69] These microorganisms are important sources of bioactive molecules against various diseases due to the extreme environment they inhabit, giving potential to an increasing number of drugs in clinical trials.
[71][72][73] Deep sea brine pools have also been a large interest in bioprospecting in the hope that unlikely environments might serve as sources of biomedical breakthroughs due to unexplored biodiversity.
