Halobacterium sp. NRC-1 is an extremophile in the domain of Archaea. Extremophiles are organisms that thrive in environments that are detrimental to the majority of life on earth. In the case of the Halobacterium they grow best in conditions of high salinity levels, between 3.8M and 4.3M. To the human eye Halobacterium can be white, yellow, red, or purple, depending on the gene that is being expressed and the environment it exists in. These salt-loving, prokaryotic organisms grow best in aerobic conditions and when exposed to sunlight.

In order to grow anaerobically Halobacterium uses the protein Bacteriorhodopsin(BR) and the presence of light in an alternate method of producing energy. Through this method of creating energy, the membrane of the Halobacterium turns purple. BR is the main component in this purple membrane. When sunlight is present, BR creates a proton gradient by moving protons out of the Halobacterium cell. The gradient is then used by ATP synthase, another membrane protein, to generate chemical energy in the form of ATP.