Astaxanthin is a high-value antioxidant pigment with superior activity compared with other antioxidants such as β -carotene and vitamins. This study developed a two-stage cultivation strategy to enhance both biomass yield and astaxanthin accumulation in Haematococcus pluvialis . In the first stage, mixotrophic growth was optimized using BG-11 medium supplemented with 7.5 g L −1 glucose, 1.5 g L −1 sodium nitrate, and 80 mg L −1 dipotassium phosphate, achieving a maximum biomass concentration of 11.6 g L −1 . In the second stage, astaxanthin biosynthesis was induced under different light-emitting diode (LED) wavelengths, light intensities, and metal ion treatments. The highest astaxanthin content was obtained under green LED light (520 nm) at an intensity of 150 µmol photons m −2 s −1 . Among the metal ions tested, sodium selenite at 25 mg L −1 resulted in the highest astaxanthin accumulation (1.85 mg g −1 ), followed by copper(II) sulfate (5 µM), which also significantly increased astaxanthin content (1.7 mg g −1 ). These findings demonstrate that the synergistic application of optimized lighting and metal ion conditions significantly enhances astaxanthin production in H. pluvialis .
Park et al. (Mon,) studied this question.