Biorefinery of the green seaweed to produce animal feed, chemicals and biofuels.

The growing world population demands an increase in animal protein production. Seaweed may be a valuable source of protein for animal feed. However, a biorefinery approach aimed at cascading valorisation of both protein and non-protein seaweed constituents is required to realise an economically feasible value chain. In this study, such a biorefinery approach is presented for the green seaweed containing 225 g protein ( × 4.6) kg dry matter (DM). The sugars in the biomass were solubilised by hot water treatment followed by enzymatic hydrolysis and centrifugation resulting in a sugar-rich hydrolysate (38.8 g L sugars) containing glucose, rhamnose and xylose, and a protein-enriched (343 g kg in DM) extracted fraction. This extracted fraction was characterised for use in animal feed, as compared to biomass. Based on the content of essential amino acids and the in vitro N (85 %) and organic matter (90 %) digestibility, the extracted fraction seems a promising protein source in diets for monogastric animals with improved characteristics as compared to the intact . The gas production test indicated a moderate rumen fermentation of and the extracted fraction, about similar to that of alfalfa. Reduction of the high content of minerals and trace elements may be required to allow a high inclusion level of products in animal diets. The hydrolysate was used successfully for the production of acetone, butanol, ethanol and 1,2-propanediol by clostridial fermentation, and the rhamnose fermentation pattern was studied.