Identification of carotenoids from the extremely halophilic archaeon Haloarcula japonica

The carotenoids produced by extremely halophilic archaeon Haloarcula japonica were extracted and identified by their chemical, chromatographic, and spectroscopic characteristics (UV-Vis and mass spectrometry). The composition (mol%) was 68.1% bacterioruberin, 22.5% monoanhydrobacterioruberin, 9.3% bisanhydrobacterioruberin, <0.1% isopentenyldehydrorhodopin, and trace amounts of lycopene and phytoene. The in vitro scavenging capacity of a carotenoid, bacterioruberin, extracted from Haloarcula japonica cells against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals was evaluated. The antioxidant capacity of bacterioruberin was much higher than that of beta-carotene.