A strategy for promoting carbon flux into fatty acid and astaxanthin biosynthesis by inhibiting the alternative oxidase respiratory pathway in Haematococcus pluvialis.

In the present study, the mechanisms for facilitating fatty acid and astaxanthin biosynthesis-related processes by inhibiting the alternative oxidase (AOX) respiratory pathway in Haematococcus pluvialis was investigated. The restriction of the AOX pathway induced the accumulation of reactive oxygen species, NAD(P)H and its substrates (acetyl-CoA, pyruvate and glyceraldehy-3-phosphate), which are required for fatty acid and astaxanthin production, thereby promoting the carbon flux into fatty acid and astaxanthin biosynthesis. During a 9-day incubation period, the fatty acid and astaxanthin contents increased by 20.6% and 20.7%, respectively, when the AOX pathway was inhibited approximately 37.7%. The AOX pathway may be inhibited by nutrient (nitrogen and phosphorus) removal, inhibitor addition and air/CO aeration adjustments in the large-scale cultivation of H. pluvialis. Therefore, the current study provides a useful enhancement strategy for fatty acid and astaxanthin coproduction and elucidates the roles of the AOX pathway in regulating fatty acid and astaxanthin biosynthesis.