Preliminary chemical characterization of unusual eubacterial exopolysaccharides of deep-sea origin

Deep-sea hydrothermal vents are characterized by specific physical and chemical parameters including high pressure, high temperature gradients and high concentrations of toxic elements. Bacteria recovered from hydrothermal vents were studied for their capability to produce polysaccharides in normal conditions. A first screening performed on mesophilic aerobic bacterial strains led to the discovery of unusual polymers in terms of chemical composition and rheological properties. Neutral polysaccharides were found, along with uronic-rich exopolymers. In addition, a new sugar was identified in two polymers. Additional studies identified this compound as a hexuronic acid substituted with an ether-linked lactic acid. The sulfate content as estimated by FTIR indicated concentrations ranging from 2 to 21%. These high sulfate concentrations are uncommon in microbial polysaccharides and may lead to new applications in the pharmaceutical area. Uronic-rich exopolymers could be expected to have some heavy metal binding capability and applications in the fields of biodetoxification and wastewater treatment.