*3.7. NMR*

Carbon-13 and proton NMR spectra were recorded with a Bruker Avance 400 spectrometer operating at a frequency of 100.618 MHz for 13C and 400.13 MHz for 1H. Samples were solubilized in D2O at a temperature of 293 K for the oligosaccharides and 353 K for the polysaccharide. Residual signal of the solvent was used as internal standard: HOD at 4.85 ppm at 293 K and 4.35 ppm at 343 K. 13C spectra were recorded using 90◦ pulses, 20,000 Hz spectral width, 65,536 data points, 1.638 s

acquisition time, 1 s relaxation delay and between 8192 and 16,834 scans. Proton spectra were recorded with a 4006 Hz spectral width, 32,768 data points, 4.089 s acquisition time, 0.1 s relaxation delay and 16 scans. The 1H and 13C-NMR assignments were based on 1H-1H homonuclear and 1H-13 C heteronuclear correlation experiments (correlation spectroscopy, COSY; heteronuclear multiple-bond correlation, HMBC; heteronuclear single quantum correlation, HSQC). They were performed with a 4006 Hz spectral width, 2048 data points, 0.255 s acquisition time, 1 s relaxation delay; 32 to 512 scans were accumulated.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/1660-3397/18/10/509/s1, Figure S1: Composition analysis of the Vibrio alginolyticus exopolysaccharide, Figure S2: Determination of absolute configuration, Figure S3: COSY spectra of the Vibrio alginolyticus exopolysaccharide before (A) and after (B) alkaline treatment, Figure S4: HSQC spectra of the Vibrio alginolyticus exopolysaccharide before (A) and after (B) alkaline treatment, Figure S5: COSY spectra recorded at 293K of the two disccharides purified by chromatography, Figure S6: HSQC spectra recorded at 293K of the two disccharides purified by chromatography, Figure S7: Positive-ion reflectron MALDI-TOF mass spectrometry analysis of the enriched fraction of the trisaccharide obtained after hydrolysis of the Vibrio alginolyticus exopolysaccharide, Table S1: Comparison of the 13C NMR chemical shifts (δ, ppm) of the Vibrio alginolyticus exopolysaccharide and the calculated values [Lipkind, et al. (1988) Carbohydr. Res. 175, 59-75].

**Author Contributions:** B.T., A.C., P.-Y.M. and R.V. produced and purified the EPS. Preliminary sugar content and composition were also done by these authors. C.B. and L.B. determined the sugar content and the linkages by chemical methods. They also measured the molecular weight of the EPS. R.C., S.D. and I.J. performed chromatography, NMR experiments and analysis. W.H. lead the project and wrote the article. All authors have read and agreed to the published version of the manuscript.

**Funding:** The research leading to these results received funding from Brittany Regional Council and OSEO as part of the FUI-AAP14 "Poly-mer" project. W.H. was supported by the Cross Disciplinary Program Glyco@Alps, within the framework "Investissements d'avenir" program (ANR-15-IDEX-02).

**Conflicts of Interest:** The authors declare no conflict of interest.
