*Article* **Structure of the Polysaccharide Secreted by** *Vibrio alginolyticus* **CNCM I-5035 (Epidermist 4.0TM)**

**Sophie Drouillard 1, Rémi Chambon 1, Isabelle Jeacomine 1, Laurine Buon 1, Claire Boisset 1, Anthony Courtois 2, Bertrand Thollas 2, Pierre-Yves Morvan 3, Romuald Vallée 3 and William Helbert 1,\***


Received: 25 September 2020; Accepted: 6 October 2020; Published: 9 October 2020

**Abstract:** *Vibrio alginolyticus* (CNCM I-5035) secretes an exopolysaccharide used as ingredient in cosmetic industry under the trademark Epidermist 4.0TM. It is appreciated for its ability to improve the physical and chemical barrier functions of the skin by notably increasing the keratinocyte differentiation and epidermal renewal. Composition analyses and in depth characterization of the polysaccharides as well as oligosaccharides obtained by mild acid hydrolyses revealed that it was composed of a repetition unit of three residues: d-galactose (d-Gal), <sup>d</sup>-*N*-acetylglucosamine (GlcNAc) and <sup>l</sup>-*N*-acetylguluronic acid, of which 30% (M/M) was acetylated in position 3. The complete structure of the polysaccharide was resolved giving the repetition unit: [→3)-<sup>α</sup>-<sup>d</sup>-Gal-(1→4)-<sup>α</sup>-<sup>l</sup>-GulNAcA/<sup>α</sup>-<sup>l</sup>-3OAc-GulNAcA-(1→4)-β-<sup>d</sup>-GlcNAc-(1→].

**Keywords:** exopolysaccharide; structure; NMR; *Vibrio alginolyticus*; Epidermist
