Figure 6.

Cultivation of D. salina using red light filters. D. salina was cultivated under white light to early orange phase (cell density of ~0.5 × 10⁶ cells mL⁻¹; carotenoid: chlorophyll ratio ~3), and then cultures were diluted with fresh medium to a cell density of ~0.2 × 10⁶ cells mL⁻¹ (no nutrient stress) (T0) and then further cultivated for 48 h under white, red or blue LED light at 1000 µmol m⁻² s⁻¹ or under white LED light at 1000 µmol m⁻² s⁻¹ covered with one of three different red filters (Lee filter 26 Bright red; Lee filter 27 Medium red; or Lee filter 787 Marius red). (a) Cellular content of 9-cis, all-trans and total β-carotene. (b) 9-cis/all-trans β-carotene ratio. Results were analysed by one way ANOVA and Tukey multiple pairwise-comparisons. Asterisks represent different levels of significance (*** 0 < p ≤ 0.001, ** 0.001 < p ≤ 0.01, * 0.01 < p ≤ 0.05).