Valorization of the pelagic Sargassum horneri for co-production of erythritol and alginate oligosaccharides

Pelagic Sargassum is invasive macroalgae with huge biomass. To produce bulk chemicals with profit from the biomass, innovative strategies need to be developed. In this study, maximum saccharification yield of Sargassum horneri biomass was obtained with the combined use of 3% alginate lyase and 3% cellulase, releasing 20.83 g/L glucose and 1.73 g/L mannitol at a 1:6 feed ratio. Subsequently, the crude S. horneri hydrolysate (pH 3.0) was proved most suitable for erythritol production of Yarrowia lipolytica strain. After 60 h fermentation in a 10-L fermenter, the erythritol concentration reached 18.42 g/L with a yield of 0.82 g/g; while the concentration of alginate oligosaccharides (AOS) was 37.56 g/L. Finally, AOS with a purity of 93.4% were obtained by ethanol precipitation, and erythritol was harvested via crystallization. This proposed strategy demonstrates the feasibility of transforming invasive Sargassum into two high-value chemicals for the first time.

Automated summary

In this study, the combined use of 3% alginate lyase and 3% cellulose in a 1:6 feed ratio resulted in the maximum saccharification yield of Sargassum horneri biomass, producing 20.83 g/L glucose and 1.73 g/L mannitol. The crude S. horneri hydrolysate (pH 3.0) was found to be suitable for erythritol production by Yarrowia lipolytica strain, achieving a concentration of 18.42 g/L and a yield of 0.82 g/g after fermentation in a 10-L fermenter for 60 hours. The proposed strategy demonstrates the feasibility of converting invasive Sargassum into high-value chemicals for the first time.