A successful biorefinery approach of macroalgal biomass as a promising sustainable source to produce bioactive nutraceutical and biodiesel

This study aimed to utilize four types of macroalgal biomass with a zero-waste biorefining concept for co-production of bioactive polysaccharide and biodiesel. The polysaccharide of macroalgal biomass obtained from Ulva spp., Sargassum spp., Cladophora spp., and Spirogyra spp. was extracted and partially purified by water-alcohol precipitation. The partially purified polysaccharide showed high antioxidant activity by scavenging DPPH and ABTS with IC50 values of 3.50-37.31 mg/mL and 0.86-8.91 mg/mL, respectively, and high antiproliferative activity on human colon cancer cell line Caco-2 with IC50 values of 0.66-12.20 mg/mL, while the antityrosinase activity was observed only Sargassum spp. and Cladophora spp. at 60.59% and 14.16%, respectively, at 10 mg/mL of tested polysaccharide extract. Interestingly, rare sugar including tagatose, psicose, and allose in polysaccharide were found to be 0.88-28.69 mg in 1 g of polysaccharide extract. After polysaccharide extraction, the macroalgal biomass residue was used to extract lipid prior to biodiesel production by acid-catalyzed transesterification. The extracted lipids of 3.09-10.05% were mainly composed of C16-C18 (>84%), and their biodiesel qualities were also satisfactory according to international requirements of biodiesel. It is expected that biorefinery approach will contribute greatly to zero-waste industrialization of macroalgal biomass-based bioactive nutraceuticals and biofuels.

Automated summary

This study utilized a zero-waste biorefining concept to co-produce bioactive polysaccharide and biodiesel from four types of macroalgal biomass. The partially purified polysaccharide extracted from the macroalgal biomass showed high antioxidant and antiproliferative activity, as well as rare sugar content. The extracted lipids were used for biodiesel production and met international requirements.