In this study, we describe the isolation and characterization of a new exopolymer that exhibits high emulsifying activities against a range of oil substrates, and demonstrates a differential capacity to desorb various mono-, di- and tri-valent metal species from marine sediment under non-ionic and seawater ionic strength conditions. This polymer, PE12, was produced by a new isolate, Pseudoalteromonas sp. strain TG12 (accession number EF685033), during growth in a modified Zobell's 2216 medium (ZM/1) amended with 1% glucose. Chemical and chromatographic analysis showed it to be a high molecular weight (>2,000 kDa) glycoprotein composed of carbohydrate (32.3%) and protein (8.2%). PE12 was notable in that it contained xylose as the major sugar component at unusually high levels (27.7%) not previously reported for a Pseudoalteromonas exopolymer. The polymer was shown to desorb various metal species from marine sediment - a function putatively conferred by its high content of uronic acids (28.7%). Seawater ionic strength (simulated using 0.6M NaCl), however, caused a significant reduction to PE12's ability to desorb the sediment-adsorbed metals. These results demonstrate the importance of electrolytes, a physical parameter intrinsic of seawater, to influencing the interaction of microbial exopolymers with metal ions. In summary, PE12 may represent a new class of Pseudoalteromonas exopolymer with the potential for use in biotechnological applications as an emulsifying or metal-chelating agent. In addition to the biotechnological potential of these findings, the ecological aspects of this and related bacterial exopolymers in marine environments is also discussed.
Gutierrez, T., Shimmield, T., Haidon, C., Black, K., & Green, D. (2008). Emulsifying and metal ion binding activity of a glycoprotein exopolymer produced by Pseudoalteromonas sp. strain TG12. Applied and Environmental Microbiology, 74(15), 4867-4876. https://doi.org/10.1128/aem.00316-08