Role of non-cellulosic polysaccharides in the structure of synthetic brown algae cell walls based on bacterial cellulose

Algae, with their diverse cell wall compositions, present great potential for food and technological applications in the global context of sustainable resource utilisation. Algae are rich in fibre, protein, fat, and bioactives, yet, they remain largely unexplored in terms of techno-functional and nutritional attributes. Their cell wall structure is primarily consisting of polysaccharides, however, understanding polysaccharide interactions and their contribution to the 3D structure of the cell walls remains elusive. Furthermore, understanding the role of non-cellulosic polysaccharides would help us overcome challenges related to cell wall disruption and modification during processing and consumption, impacting extraction of bioactives, nutrient bioaccessibility as well as fermentation by gut microbiota.

Our project aims to build on previous results obtained at ALBA using WAXS and SAXS, on cellulose-based synthetic cell walls, showing that alginate and fucoidan, both non-cellulosic polysaccharides present in brown macroalgae, were interspaced with the cellulose microfibrils, increasing the distance between them, but still forming relatively ordered and packed structures. These structures were modified when the synthetic cell walls were processed by freeze-drying, and they were not able to recover their native structures upon rehydration. Encouraged by this impactful results, we would like to continue exploring the role of polysaccharides on cellulose based cell walls using bacterial cellulose hydrogels as brown algae cell wall biomimetics. A deeper understanding of the role of algae polysaccharides on cell wall structure, as well as increase knowledge of the impact of processing on macroalgae, would help us optimised manufacturing and valorisation of this marine biomass.