Microalgae and cyanobacteria are photosynthetic organisms that can produce/accumulate biomolecules with industrial interest. Among these molecules, EPSs are macromolecular polysaccharidic compounds that present biological activities and physico-chemical properties, allowing to consider their valorization in diverse commercial markets, such as cosmetic, therapeutic, nutraceutic, or hydrocolloids areas. The number of microalgae and cyanobacteria strains described to produce such EPSs has increased in recent years as, among the 256 producing strains gathered in this review, 86 were published in the last 10 years (~33%). Moreover, with the rise of research on microalgae EPSs, a variety of monosaccharides compositions have been discovered, highlighting the versatility of these organisms. If some production strategies can be applied to increase EPS production yields, it appears that case by case studies are needed to promote EPS synthesis by a strain, as many responses exist. This paper proposes an up-to-date state of the art of the diversity of microalgae and cyanobacteria EPS-producing strains, associated to the variability of compositions. The strategies for the production and extraction of the polymers are also discussed. Finally, an overview of the biological activities and physico-chemical properties allow one to consider their use on several commercial markets.

Publications and patents relative to newly observed functions of β-(1,3)-D-glucans have notably increased in the last few years with the exploitation of their biological activities. The term β-(1,3)-D-glucans includes a very large number of polysaccharides from bacterial, fungal and vegetable sources. Their structures have a common backbone of β-(1,3) linked glucopyranosyl residues but the polysaccharidic chain can be β-(1,6) branched with glucose or integrate some β- (1,4) linked glucopyranosyl residues in the main chain. Except for the curdlan, a bacterial linear β-(1,3)-D-glucans, and for the scleroglucan produced by Sclerotium rolfsii, the main drawback limiting the development of these polysaccharides is the lack of efficient processes for their extraction and purification and their cost. However new applications in agronomy, foods, cosmetic and therapeutic could in a next future accentuate the effort of research for their development. So this review focuses on these β-(1,3)-D-glucans with the objective to detail the strategies employed for their extraction and the relation structure-functions identified when they induce biological activities.