Enhanced astaxanthin production from Haematococcus pluvialis using butylated hydroxyanisole

- Butyl hydroxyanisd could increase biomass concentration and astaxanthin content.
- The highest astaxanthin production was obtained at late-exponential growth phase.
- The transcriptional levels of seven genes were enhanced in treated samples.
- The expression of fatty acid related genes increased with astaxanthin accumulation.

Haematococcus pluvialis is a promising natural source of high-value antioxidant astaxanthin under stress conditions. Biotic or abiotic elicitors are effective strategies for improving astaxanthin production in H. pluvialis. Butylated hydroxyanisole (BHA) was identified as an effective inducer for H. pluvialis LUGU. Under a treatment of 2 mg L−1 BHA (BHA2), astaxanthin content reached a maximum of 29.03 mg g−1 dry weight (DW) (2.03-fold of that in the control) after 12 day of the mid-exponential growth phase. Subsequently, H. pluvialis LUGU was subjected to BHA2 at different growth phases because an appropriate time node for adding elicitors is vital for the entire production to succeed. As a result, the highest astaxanthin content (29.3 mg g−1 DW) was obtained in cells on day 14 (BHA2 14) of the late-exponential growth phase. Furthermore, the samples treated with BHA2 14 and the control group were compared in terms of the transcriptional expression of seven carotenogenesis genes, fatty acid composition, and total accumulated astaxanthin. All selected genes exhibited up-regulated expression profiles, with chy, crtO, and bkt exhibiting higher maximum transcriptional levels than the rest. Oleic acid content increased 33.15-fold, with acp, fad, and kas expression being enhanced on the day when astaxanthin was produced rapidly.

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