Question

How do halophiles live in high salt concentrations? Specifically, in terms of water movement (how do they prevent that movement of water).

Answer 1

Halophiles live in extreme saline environment to which few organisms could adapt and occupy. Halophiles spend energy to remove salt from their cytoplasm to avoid salting out or aggregation of protein.

They use two different approaches to survive in extreme saline conditions to prevent dehydration through osmotic movement of water out of their cytoplasm by increasing the internal osmolarity of the cell. In one method, organic compounds known as osmoprotectants are gathered in the cytoplasm. These are synthesized or accumulated from the environment. Commonly used osmoprotectants are neutral or zwitterionic, and include amino acids, sugars and derivatives of some of these compounds. Second method involves selective influx of potassium (K+) ions into the cytoplasm.

In halophiles the entire intracellular machinery (enzymes, structural proteins, etc.) are adapted to high salt levels.There are some prokaryotes that require salt for growth. They can’t survive if the environment is not extremely saline. The high concentration of salt in this environment limits the availability of oxygen for respiration. Their cellular machinery is adapted to high salt concentrations by using charged amino allowing them to retain the water molecules around.