Aurélie Préchoux1, Benoit Queguineur1, Fatma Hachani1, Isabelle Mussio2, Anne-Marie Rusig2, Franck Hennequart1
1ALGAIA, Research and Development Centre, 91 rue Edouard Branly, 50000 Saint Lô, France
2BOREA, UMR 8067, CNRS, MNHN, IRD, SU, UCN, UA, University Caen Normandy, 14033 CAEN, France
The aim of this project was to offer viable solutions to the socio-environmental problems of beach-cast seaweeds in Normandy. In Grandcamp-Maisy, the beach-cast was heterospecific with red, brown, and green macroalgae, mainly coming from a reef stretching for 5,60 km². During almost 3 years, beach-casts were studied: biomass, floristic biodiversity but above all, analytical composition with the goal to determine the baseline composition of this heterogeneous biomass. The objectives were two-fold: 1- find added-value for the heterogenous biomass, and 2- investigate the harvesting impact of the invasive Sargassum muticum on the reef before it is torn into beach-cast. Regarding the first axis, several added-value applications were explored generating very interesting results due to the diversity of biomolecules in these mixes of seaweeds. However, the most promising applications in term of economic viability are, on the one hand, the incorporation of these seaweeds in bioplastics – a proof of concept was the production of 500 “Ecocups” – and, on the other hand, the production of a liquid bio-stimulant. An extraction process has been developed to obtain compounds of interest, notably oligosaccharides and peptides, both at lab and pilot scale. The formulated extracts have proved bio-stimulant activity on agronomic tests : first on germination assays, then on lettuce cultivation improving drought resistance (+62% biomass). Moderate analytical variations of beach-cast allowed to maintain a baseline composition and the bio-stimulant activity in the extracts. A biorefinery model can be suggested by recycling the co-product of biostimulant extraction process into bioplastics.