Final answer:
A halophile is an organism that tolerates high salt concentrations, requiring at least 0.2 M to thrive. Halophiles, like Halobacterium salinarum, have specialized adaptations for surviving in hypersaline environments unlike halotolerant organisms that can tolerate but do not require high salt levels.
Step-by-step explanation:
An organism that tolerates high salt concentrations is called a halophile. Halophiles are extremophiles that thrive in environments where the salt concentration is significantly high, such as in the Dead Sea. They require a salt concentration of at least 0.2 M for growth. Some examples of halophiles include the archaeon Halobacterium salinarum and certain species of Dunaliella.
These organisms have adapted to their hypersaline environments by evolving cellular mechanisms that balance osmotic pressure, such as accumulating high concentrations of glycerol or pumping out salt ions. In contrast, halotolerant organisms can grow in high salt conditions but do not necessarily need them for survival. An example of halotolerant bacteria includes species like Halomonas spp.
It's important to note that halophiles are different from other extremophiles such as acidophiles, which thrive at low pH levels, or barophiles, which require high atmospheric pressure for growth.