Biotechnological production of bacterial exopolysaccharides and applications in cosmetics

Polysaccharides can be defined as macromolecules formed by the concatenation of similar units, in this case carbohydrates commonly referred to as "sugars" or "oses". Initially dominated by gums of plant and algal origin, their market is also opening up to bacterial polysaccharides. In the marine environment, this production seems to be dominated by strains belonging to the genera Alteromonas, Pseudoalteromonas, Pseudomonas, Shewanella and Vibrio. In bacteria, these polysaccharides are present :

• in the cell wall;

• outside the cell but bound to it (capsular polysaccharide);

• or released into the culture medium in the form of exopolysaccharides (EPS).

In the majority of cases (with the exception of known cases such as levans and dextrans), these EPS are synthesized inside the bacterial cell and excreted into the environment in the form of macromolecules. Although we can assume that this mode of synthesis is also found in marine bacteria, we have to admit that there are few studies on the subject.

For many reasons, including those linked to the way they are obtained and extracted, EPS are biopolymers of great interest from a biotechnological point of view, and this for many industrial sectors (health, agri-food, cosmetics, environment, enhanced oil recovery, bioremediation, etc.).

Generally speaking, a strategy for adding value to these bacterial EPS involves a succession of different stages: sampling, creation of a collection ("strain library") and its management, screening, laboratory production and determination of the characteristics and properties of the biopolymers, their development (optimization studies, choice of strategies, etc.) and production on a pre-industrial and industrial scale, prior to possible commercialization. This article describes these different stages and the problems that can be associated with them, with the cosmetics industry as an example of applications for these marine biopolymers.