TABLE 2.
Production of carotenoids and sterols in X. dendrorhous strains
| Metabolite | Strain | ||||
| CBS 6938 (wild-type) | CBS.Δstp1 | CBS.cyp61− | CBS.cyp61−.Δstp1 | CBS.Δstp1/STP1 | |
| Total carotenoids (μg/g; 100%) | 287 ± 15a | 260 ± 9a | 442 ± 34b | 264 ± 16a | 292 ± 10a |
| Astaxanthin (%) | 70.4 | 70.4 | 74.5 | 66.3 | 70.1 |
| β-carotene (%) | 1.4 | 1.2 | 1.0 | 1.9 | 0.5 |
| Intermediary carotenoids from β-carotene to astaxanthin (%) | 15.9 | 18.1 | 8.9 | 24.4 | 14.7 |
| Other carotenoids (%) | 12.2 | 10.3 | 15.5 | 7.4 | 14.7 |
| Total sterols (mg/g; 100%) | 3.7 ± 0.1a | 3.5 ± 0.1a | 5.0 ± 0.2b | 3.6 ± 0.1a | 3.8 ± 0.4a |
| Ergosterol, peak at 16.5 min (%) | 96.1 | 97.4 | ND | ND | 97.5 |
| Peak 1 at 7.2 min (%) | 3.9 | 2.6 | 3.6 | 4.4 | 2.5 |
| Peak 2 at 13.5 min (%) | ND | ND | 27.3 | 14.8 | ND |
| Peak 3 at 19.5 min (%) | ND | ND | 69.1 | 80.8 | ND |
Total carotenoids and sterols were extracted after 120 h of culture and normalized to the yeast dry weight in grams. The table shows the mean ± standard deviation of three independent cultures of each strain. Intermediate carotenoids from β-carotene to astaxanthin include phoenicoxanthin, OH-echinenone, and echinenone; other carotenoids include torulene, OH-k-torulene, and other unidentified carotenoids. Peaks 1, 2, and 3 correspond to metabolites having a sterol spectrum, which were observed in chromatograms after approximately 7.2, 13.5, and 19.5 min of retention time, respectively. Data were evaluated with one-way ANOVA and the Tukey post hoc test to compare metabolite production between strains. Superscript letters indicate statistical comparisons: having the same letter denotes no statistically significant differences, and having different letters indicates significant differences between strains with P < 0.05. ND, not detected.