Emulsifying and Metal Ion Binding Activity of a Glycoprotein Exopolymer Produced byPseudoalteromonassp. Strain TG12

Abstract

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 trivalent metal species from marine sediment under nonionic and seawater ionicstrength 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 amended with 1% glucose. Chemical and chromatographic analysis showed it to be a high-molecular-mass (>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 0.6 M NaCl), however, caused a significant reduction in PE12's ability to desorb the sediment-adsorbed metals. These results demonstrate the importance of electrolytes, a physical parameter intrinsic of seawater, in influencing the interaction of microbial exopolymers with metal ions. In summary, PE12 may represent a new class of Pseudoalteromonas exopolymer with a 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 are also discussed.

Biosurfactant production by Arctic and Antarctic bacteria growing on hydrocarbons

“…Strains within the former genus can produce extracellular polymeric substance (EPS), also in polar environments (Bozal et al 1994;Mancuso et al 2004Mancuso et al , 2005. However, a unique study exists on the production of a polymeric emulsifying agent by a pseudoalteromonad under mesophilic conditions (Gutierrez et al 2008). Interestingly, we recently reported (Rizzo et al 2013).…”

Yield and physicochemical properties of EPS from Halomonas sp. strain TG39 identifies a role for protein and anionic residues (sulfate and phosphate) in emulsification of n‐hexadecane

“…To investigate this, we are presently evaluating the metal ion binding specificity and affinity of EPS from strain TG39 under experimental conditions simulating seawater ionic strength, as previously performed by our group using other marine bacterial EPS (Gutierrez et al, 2008).…”

Emulsifying behaviour and rheological properties of the extracellular polysaccharide produced by Pseudomonas oleovorans grown on glycerol byproduct

“…Other biopolymers with potential applications as bioemulsifiers include extracellular polysaccharides produced by Pseudomonas tralucida (Appaiah & Karanth, 1991), Pseudoalteromonas sp. (Gutierrez, Schimmield, Haidon, Black, & Green, 2008), Zoogloea sp. (Lim, Kim, Kim, Yoo, & Kong, 2007) and Enterobacter cloaceae (Iyer, Mody, & Jha, 2006).…”