Fig. 7
The effect of carbon availability on astaxanthin synthesis in C. zofingiensis under ND conditions. The algal cultures were bubbled with 0.04%, 1.5% or 5% CO2. a The time course color change of cultures. b TLC analysis of carotenoids from the algal samples after 48 h of cultivation. 1 β-carotene, 2 astaxanthin di-ester, 3 astaxanthin mono-ester, 4 origin. c The content of carotenoids. d Transcriptional level of carotenogenic genes as determined by qPCR. The gene expression level was normalized to the internal control β-actin gene. e The content of TFA and TAG. f The ratio of astaxanthin/TFA and astaxanthin/TAG. The data are expressed as mean ± SD (n = 3). Different letters above the bars in each panel of c–f indicate significant difference (p < 0.05), based on One-way ANOVA with post hoc Tukey’s HSD test