Laminaria japonica hydrolysate promotes fucoxanthin accumulation in Phaeodactylum tricornutum

[Display omitted] •LPH promote fucoxanthin accumulation and growth in P. tricornutum simultaneously.•Plant hormones were found to promote fucoxanthin accumulation for the first time.•Genes related to fucoxanthin formation were generally up-regulated. Fucoxanthin (Fx) has gained a growing attention due to the remarkable biological activities. The limited biomass of was the restrictive factor for Fx production in Phaeodactylum tricornutum. In this study, Laminaria japonica hydrolysate (LPH) with a low addition proportion of 1.5 ml/L, was proved to promote fucoxanthin accumulation and cell growth simultaneously. Fx topped at 27.9 mg/L after 10-d cultivation in the LPH group, with a biomass of 1.59 g/L and a Fx content of 17.55 mg/g. Three key plant hormones in LPH were screened responsible for promoting fucoxanthin accumulation. Transcriptomic analysis and qRT-PCR results showed that genes related to Fx formation were generally up- regulated. The study demonstrated that LPH addition was a feasible and efficient strategy to enhance production of fucoxanthin, facilitating the scale-up production of Fx in autotrophic culture.