Method for producing astaxanthin by fermentation

A method for producing carotenoids comprising:

• 1) culturing a bacterial strain in a culture medium containing biotin at a concentration of 0.02 mg/L to 50 mg/L by addition of biotin to the culture medium, wherein the bacterial strain is a member of the genus Paracoccus and concurrently produces astaxanthin and canthaxanthin;
• 2) increasing the concentration of dissolved oxygen in the culture medium in a stepwise or continuous manner during the intermediate phase of culture, wherein the concentration of dissolved oxygen in the culture medium at the beginning of the intermediate phase of culture before increasing the concentration is 2 ppm to 3.5 ppm, and the concentration of dissolved oxygen in the culture medium after increasing the concentration during the intermediate phase of culture is 3.5 ppm to 7 ppm, thereby producing a carotenoid-containing culture broth in which the ratio of the concentration of canthaxanthin to the concentration of astaxanthin in the culture broth at the end of the culture period is 8% by mass or less;
• and
• 3) collecting the carotenoids from the carotenoid-containing culture broth.