Simultaneous production of β-carotene, vitamin E and vitamin C by the aerial microalga Trentepohlia aurea

The biomass production and antioxidant accumulation of the aerial microalga Trentepohlia aurea were examined. Using ammonium chloride as nitrogen source for growth in liquid medium, the growth rate was exponential and accompanied by a marked fall in the pH of the medium. The highest growth rate of 152 mg L-1 day(-1) (logarithmic phase) was attained when T. aurea was cultured with aeration of 5% CO2-enriched air in medium buffered with HEPES. The growth rate and antioxidant content were enhanced under 5% CO2 by switching the light intensity from 43 to 143 mu mol photon m(-2) s(-1) for the two-stage culture. As a result, T. aurea cells accumulated 2.1 mg beta-carotene, 0.3 mg L-ascorbic acid and 2.4 mg tocopherols, respectively, per g dry cell. The simultaneous production of useful materials, such as beta-carotene, vitamin E and vitamin C, was demonstrated.