Exopolysaccharide from marine microalgae belonging to the Glossomastix genus: fragile gel behavior and suspension stability

ABSTRACT

With the aim to find new polysaccharides of rheological interest with innovated properties, rhamnofucans produced as exopolysaccharides (EPS) in a photobioreactor (PBR) and an airlift bioreactor (ABR) by the marine microalgae Glossomastix sp. RCC3707 and RCC3688 were fully studied. Chemical characterizations have been conducted (UHPLC – MS HR). Analyses by size-exclusion chromatography (SEC) coupled online with a multiangle light scattering detector (MALS) and a differential refractive index detector showed the presence of large structures with molar masses higher than 10⁶ g.mol⁻¹. The rheological studies of these EPS solutions, conducted at different concentrations and salinities, have evidenced interesting and rare behavior characteristic of weak and fragile hydrogels i.e. gel behavior with very low elastic moduli (between 10⁻² and 10 Pa) and yield stresses (between 10⁻² and 2 Pa) according to the EPS source, concentration, and salinity. These results were confirmed by diffusing wave spectroscopy. Finally, as one of potential application, solutions of EPS from Glossomastix sp. have evidenced very good properties as anti-settling stabilizers, using microcrystalline cellulose particles as model, studied by multiple light scattering (MLS) with utilization in cosmetic or food industry. Compared to alginate solution with same viscosity for which sedimentation is observed over few hours, microalgae EPS leads to a stable suspension over few days.

Graphical Abstract

KEYWORDS:

• Polysaccharide
• microalgae
• Glossomastix
• fragile gel
• stabilizer

Disclosure statement

The corresponding author confirms on behalf of all authors that there have been no involvements that might raise the question of bias in the work reported or in the conclusions, implications, or opinions stated, including the involvement of Philippe Michaud, coauthor of the work and also Deputy Editor of Bioengineered.

Author contributions statement

VD: Conceptualization, Investigation, Writing- Original Draft preparation. CR: Investigation, Validation. CG: Investigation, Validation. NB: Supervision, Investigation, Validation. PG: Investigation, Validation. CL: Supervision, Investigation, Validation. GP: Investigation, Validation. TV: Investigation, Validation. IP: Investigation, Validation, Project administration. TM: Supervision, Project administration. PM: Supervision, Writing- Reviewing and Editing, Project administration, Funding acquisition. LP: Supervision, Validation, Writing- Reviewing and Editing, DLC: Supervision, Writing- Reviewing and Editing, Project administration

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article and its supplementary materials, and may be shared upon request.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/21655979.2023.2296257

Additional information

Funding

This work was supported by the French National Research Agency [ANR POLYSALGUE project] under Grant number [ANR-15-CE21-0013]; Normandy Region; and the European Union.