Isorenieratene /ˌaɪsoʊrəˈnɪərətiːn/ is a carotenoid light-harvesting pigment produced exclusively by the genus Chlorobium, which are the brown-colored strains of the family of green sulfur bacteria (Chlorobiaceae).

Therefore, the discovery of isorenieratene and its derivatives in sediments and rocks are helpful biomarkers to identify euxinic water columns in the photic zone.

The nine conjugated double bonds on the isoprenoid backbone are all in the trans configuration and make the molecule highly reactive with reduced inorganic sulfur species.

The Black Sea is one such water basin where the hydrogen sulfide interface, or the chemocline, has moved up in the photic zone, and high concentrations of green sulfur bacteria and isorenieratene are found.

[13] The two main transformation processes are the saturation of double bonds to form isorenieratane and the rupture of the carbon chain resulting in smaller molecular fragments.

The detection of isorenieratene and green sulfur bacteria in the mid-Proterozoic has been used as evidence for the long-term euxinic conditions remaining in oceans after the Great Oxygenation Event.

For example, the 1.64-Gyr-old Barney Creek Formation in northern Australia hosts many biomarkers, including isorenieratene, that signify that these rocks were deposited in a marine basin with anoxic, sulphidic, and highly-stratified deep waters with colonies of green and purple sulfur bacteria.

[14] Isorenieratene derivatives have been identified in sedimentary rocks throughout the Paleozoic and Mesozoic, signifying that anoxygenic photosynthesis was a more common process in the past.