UV protection[edit]
There is little protection from the Sun in salt ponds, so H. salinarum are often exposed to high amounts of UV radiation. To compensate, they have evolved a sophisticated DNA repair mechanism. The genome encodes DNA repair enzymes homologous to those in both bacteria and eukaryotes.[1] This allows H. salinarum to repair damage to DNA faster and more efficiently than other organisms and allows them to be much more UV tolerant.
H. salinarum is responsible for the bright pink or red appearance of the Dead Sea and other bodies of salt water. This red color is due primarily to the presence of bacterioruberin, a 50 carbon carotenoid pigment present within the membrane of H. salinarum. The primary role of bacterioruberin in the cell is to protect against DNA damage incurred by UV light.[13] This protection is not, however, due to the ability of bacterioruberin to absorb UV light. Bacterioruberin protects the DNA by acting as an antioxidant, rather than directly blocking UV light.[14] It is able to protect the cell from reactive oxygen species produced from exposure to UV by acting as a target. The bacterioruberin radical produced is less reactive than the initial radical, and will likely react with another radical, resulting in termination of the radical chain reaction.[15]