Spent yeast as an efficient medium supplement for fucoxanthin and eicosapentaenoic acid (EPA) production by Phaeodactylum tricornutum

Fucoxanthin and eicosapentaenoic acid (EPA) are high-value compounds that can be found in the marine diatom Phaeodactylum tricornutum . Yet, the growth rate of this microalga is relatively low under photoautotrophic conditions. The purpose of this study was to evaluate the feasibility of using spent yeast, the second-major by-product of the brewing industry, as a useful substrate for P. tricornutum cultivation. Different pretreatments, concentrations of spent yeast, and initial cell densities of P. tricornutum were investigated. After 12 days of cultivation in f/2 medium, P. tricornutum supplemented with 1.33 g L −1 preautoclaved spent yeast yielded 3.28 times more fucoxanthin (5.97 mg L −1 ) and 3.55 times more EPA (16.82 mg L −1 ) than P. tricornutum grown without the yeast (fucoxanthin 1.82 mg L −1 , EPA 4.64 mg L −1 ). Nutrient analysis showed that the nitrogen and phosphorus released by the spent yeast were consumed over time. Overall, spent yeast effectively promoted the fucoxanthin and EPA yields of P. tricornutum .