Bioproducts from marine macroalgae Caulerpa taxifolia: production of biodiesel, biochar and biopolysaccharide using biorefinery approach.

Seaweeds have been consumed as food traditionally, which has garnered renewed interest from researchers and industry as a prolific source of bioactive metabolites with biological significance. This study aimed to extract bioproducts from the invasive Caulerpa taxifolia including lipids and biochar for biodiesel production and polysaccharides for wound-healing applications. For this, three different methods like mechanical, water bath and ultrasound assisted extractions were performed with seven seaweeds including Halimeda gracilis, Turbinaria conoides, Sargassum polycystum, Caulerpa taxifolia, Padina boergesenii, Spatoglossum asperum and Gracilaria crassa. Among them, higher lipid content (5.7 ± 0.04%) was scored with Caulerpa taxifolia by water bath-assisted extraction. The leftover seaweed biomass was further subjected to recovery of polysaccharides through ultrasound, microwave and ultrasound-microwave-assisted extractions, in which the ultrasound-assisted extraction yielded a maximum of 4.1 ± 0.05%. Structural confirmation of the extracted crude polysaccharide was evaluated by FT-IR, XRD and TGA. Then, the synthesized and seaweed-derived activated biochar catalyst (SDABC) was employed for the transesterification that enhanced the FAME recovery up to 96% of SFA and MUFA than homogenous catalysts. The structural moieties of seaweed derived biochar catalyst (SDBC) and SDABC were characterized by FT-IR, BET, SEM, and EDX analysis. Furthermore, the extracted crude polysaccharides (50, 100 and 150 µg/mg) were examined for wound-healing in C. elegans and the worms healed within 24 h at 150 µg/mg, which showed the polysaccharide efficacy against therapeutic potential. In conclusion, this study demonstrates the utilization of the entire seaweed biomass of underexploited C. taxifolia to produce various bioproducts through zero-waste concept.