a purple protein containing retinal and found in the plasma membrane of certain bacteria (genus Halobacterium): it directly supplies electrochemical energy from sunlight
See bacteriorhodopsin in American Heritage Dictionary 4
(băk-tîrˌē-ō-rō-dŏpˈsĭn)
noun
A purple pigment similar to rhodopsin occurring in the cell membranes of bacteria of the genus Halobacterium that converts sunlight directly into chemical energy.