Preliminary Investigation of the Carotenoid Compositionof Erythrobacter sp. Strain KJ5 by High-PerformanceLiquid Chromatography and Mass Spectrometry

Separation and identification of carotenoids (Cars) from aerobic marine bacterium Erythrobacter sp. strain KJ5 are reported. The cells of Erythrobacter sp. were grown in a Shioi medium at 28.5°C for three days. Among the four solvents tested, the mixture of methanol and acetone (3:7, v/v) was determined as the optimum solvent for Car extraction from the cells by measuring its absorption spectrum. The Cars were separated via reversed-phase high-performance liquid chromatography using a C8 column and identified by a UV-Vis photodiode array detector and an electrospray ionization mass spectrometry. Bacteriochlorophyll a was not detected from the extracts of cells grown under both light and dark conditions. At least 16 peaks of Cars were separated, wherein eleven peaks showed the same absorption spectrum with λmax at 452-453 nm and at 478-480 nm. The other five peaks had an additional absorption peak at 340 nm, which belongs to cis-isomeric form. Two peaks of Cars were identified to be zeaxanthin and β-carotene.