Characterization and Biotechnological Potential of Extracellular Polysaccharides Synthesized by Alteromonas Strains Isolated from French Polynesia Marine Environments.

Patrícia Concórdio-Reis,Vítor D Alves,Maria A M Reis,Jean Guézennec,Filomena Freitas,Xavier Moppert

doi:10.3390/md19090522

Patrícia Concórdio-Reis, Vítor D Alves + Show 4 more

Open Access

https://doi.org/10.3390/md19090522

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Abstract

Marine environments comprise almost three quarters of Earth’s surface, representing the largest ecosystem of our planet. The vast ecological and metabolic diversity found in marine microorganisms suggest that these marine resources have a huge potential as sources of novel commercially appealing biomolecules, such as exopolysaccharides (EPS). Six Alteromonas strains from different marine environments in French Polynesia atolls were selected for EPS extraction. All the EPS were heteropolysaccharides composed of different monomers, including neutral monosaccharides (glucose, galactose, and mannose, rhamnose and fucose), and uronic acids (glucuronic acid and galacturonic acid), which accounted for up to 45.5 mol% of the EPS compositions. Non-carbohydrate substituents, such as acetyl (0.5–2.1 wt%), pyruvyl (0.2–4.9 wt%), succinyl (1–1.8 wt%), and sulfate (1.98–3.43 wt%); and few peptides (1.72–6.77 wt%) were also detected. Thermal analysis demonstrated that the EPS had a degradation temperature above 260 °C, and high char yields (32–53%). Studies on EPS functional properties revealed that they produce viscous aqueous solutions with a shear thinning behavior and could form strong gels in two distinct ways: by the addition of Fe2+, or in the presence of Mg2+, Cu2+, or Ca2+ under alkaline conditions. Thus, these EPS could be versatile materials for different applications.

Highlights

Sea water covers more than 70% of the earth’s surface and represents the largest ecosystem of the planet
Important molecules for cell survival are extracellular polysaccharides (EPS), high molecular weight carbohydrate polymers secreted by many microorganisms, bacteria [5,6]
High content in uronic acids and sulfate groups are found within marine bacteria derived EPS, which further contributes to their unique properties [13]

Summary

Introduction

Sea water covers more than 70% of the earth’s surface and represents the largest ecosystem of the planet. From the shallow coastal waters to the deep ocean, marine habitats have a variety of unique ecological characteristics that prompted marine microbial communities to develop adaptation mechanisms in order to survive [2,3] This is especially true in extreme environments such as those found in deep-sea, hydrothermal vents, volcanic and hydrothermal marine areas, marine salterns, and sea ice in polar regions [4]. Marine bacteria are currently a very promising source for the discovery of EPS with distinctive structures and unique properties, with applicability in several industrial sectors [1,13] These EPS often exhibit a high diversity in structure and composition, that might include rare sugars, such as fucose or rhamnose [13,14], which are known to confer the biopolymers’ biological activity [12]. High content in uronic acids and sulfate groups are found within marine bacteria derived EPS, which further contributes to their unique properties [13]

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