Abstract:

The mild extraction of carotenoids from Rhodococcus sp. using lysozyme, which can break down the bacterial
cell wall efficiently and specifically, was achieved. An orthogonal array design was employed to determine the optimal
hydrolysis conditions as follows: bacterial cell powder/lysozyme ratio, 1:10 (mg/mL); hydrolysis time, 80 min; and solid/
liquid ratio, 1:80 (mg/mL). The extracted carotenoids were identified by liquid chromatography-mass spectrometry (LC-MS).
The samples were separated on a YMCC30 column (4.6 mm × 150 mm, 5 μm) and detected at 450 nm. LC-MS conditions
were set as follows: atmospheric-pressure chemical ionization (APCI) source, positive ion mode, ion source temperature of
230 ℃, charging voltage of 2 000 V and scanning range for mass-to-charge ratio of 200–1 200. The results showed that two
kinds of carotenoids were identified and their chemical formulas were C51H76O2 and C51H74O2, respectively.

Key words: carotenoid, enzymatic extraction method, high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS), Rhodococcu sp. B7740