Myo-inositol facilitates astaxanthin and lipid coproduction in Haematococcus pluvialis by regulating oxidative stress and ethylene signalling

In the present study, exogenous myo-inositol (MI) was applied to induce natural astaxanthin and biolipid accumulation in Haematococcus pluvialis. Under 200 μM MI, algal cells exhibited 62.11 % and 34.67 % increases in astaxanthin and lipid content, respectively, compared to the control. The carotenogenesis and lipogenesis genes were upregulated by induction of MI. Interestingly, MI addition elevated the ethylene (ETH) content and activated antioxidant enzyme-associated gene levels, which could be involved in alleviating oxidative stress. Further data showed that the ETH signal played a positive function in stimulating astaxanthin biosynthesis under MI induction. Supplementation with ethephon plus MI boosted the astaxanthin content to 33.08 ± 0.03 mg g