Chromochloris zofingiensis is a promising source of high-value bioproducts, particularly carotenoids and fatty acids. In this study, three selected chemical agents, including methylene blue (MB), salicylic acid (SA), and zinc sulfate heptahydrate (ZN), representing their roles as an oxidant, a signal transducer, and a metal ion, respectively, were applied at 96 h post-inoculation to stimulate metabolite accumulation via a two-stage cultivation approach. None of the treatments significantly affected algal growth. Among the treatments, HPLC analysis showed that 2.5 mM ZN significantly exhibited a dual stimulatory effect on astaxanthin (1.679 ± 0.122 mg g−1) and lutein (4.257 ± 0.183 mg g−1) accumulation, which were 2.28- and 2.91-fold higher than the control, respectively. The 1 µM MB significantly enhanced the canthaxanthin content to 2.382 ± 0.210 mg g−1 (a 3.57-fold increase). Different SA concentrations selectively induced the target pigments of astaxanthin and lutein. APCI-QTOF analysis enabled the detection of echinenone in the microalgal extracts. Its identity and quantification were subsequently validated by HPLC, with the highest content detected under the 0.2 mM SA treatment. GC-FID analysis revealed changes in the composition of six major fatty acids, with C18:1 n-9 representing 50.01% of the total fatty acids under the 2.5 mM ZN treatment. These findings suggest that the two-stage approach could offer a practical and feasible strategy for microalgal biorefineries.
Niyompanich et al. (Mon,) studied this question.