Isolation, characterization and optimization of EPSs produced by a cold-adapted Marinobacter isolate from Antarctic seawater

Marinobacter sp. W1-16 from Antarctic surface seawater was analysed for the production of extracellular polymeric substances (EPSs). Enhancement of the EPS biosynthesis was carried out by evaluating the influences of the carbon source (type and concentration), temperature, pH and salinity. EPS yields varied strongly depending on sugar substrate and temperature, while pH and salinity did not strongly affect levels of EPS production. Marinobacter sp. W1-16 produced the highest quantity of EPSs when growing at 15°C and pH 8, in the presence of 2% glucose and 3% NaCl. The EPS chemical characterization revealed a molecular weight of about 260 kDa. Colorimetric assays determined a higher quantity of carbohydrate than of proteins and uronic acids, as well as the presence of sulphate, in the extracted EPSs. The monosaccharidic composition resulted in Glc:Man:Gal:GalN:GalA:GlcA in relative molar proportions of 1:0.9:0.2:0.1:0.1:0.01. Some biotechnological potentialities (i.e. emulsifying and cryoprotective actions, and heavy metal binding properties) of the EPSs were proved, suggesting possible industrial and bioremediation applications.