Copper but not iron limitation increases astaxanthin production by Phaffiarhodozyma in a chemically defined medium

The influence of copper (0-32 muM) and iron (0-108 muM) on growth and astax anthin production by Phaffia rhodozyma was studied. Copper below 3.2 muM in creased the astaxanthin content of the cells (from 220 to 287 mug g(-1)) bu t at the expense of a slightly decreased growth (from 11.3 to 10.2 mg ml(-1 )). In contrast, iron below 1 muM decreased both the growth and astaxanthin content of the cells. Using copper limitation instead of toxic respiratory inhibitors to improve astaxanthin production has obvious advantages from t he product quality, environmental and process operation points of view.