Deinococcus

Deinococcus (from Ancient Greek δεινός (deinós), meaning "dreadful", and κόκκος (kókkos), meaning "grain") is in the formerly monotypic family Deinococcaceae, and one genus of three in the order Deinococcales of the bacterial phylum Deinococcota highly resistant to environmental hazards. These bacteria have thick cell walls that give them Gram-positive stains, but they also include a second membrane and are therefore closer in structure to Gram-negative bacteria. Deinococcus survive when their DNA is exposed to high doses of gamma and UV radiation. Whereas other bacteria change their structure in the presence of radiation, such as by forming endospores, Deinococcus tolerate it without changing their cellular form and do not retreat into a hardened structure. They are also characterized by the presence of the carotenoid pigment deinoxanthin that give them their pink color. They are usually isolated according to these two criteria. In August 2020, scientists reported that bacteria from Earth, particularly Deinococcus bacteria, were found to survive for three years in outer space, based on studies conducted on the International Space Station. These findings support the notion of panspermia, the hypothesis that life exists throughout the Universe, distributed in various ways, including space dust, meteoroids, asteroids, comets, planetoids or contaminated spacecraft.

== Molecular signatures == Members of Deinococcus can be distinguished from all other bacteria through molecular signatures known as conserved signature indels (CSIs) and proteins (CSPs). An earlier study on Deinococcus identified nine CSIs and 58 CSPs which were exclusively shared by members of this genus. Some of the identified CSPs such as the DNA damage repair protein PprA and the single-stranded DNA-binding protein DdrB are thought to have functional roles in the DNA repair mechanism and radioresistance phenotype of Deinococcus.