Production of a new exopolysaccharide (EPS) by Pseudomonas oleovorans NRRL B-14682 grown on glycerol

Pure glycerol and glycerol-rich product (GRP) obtained from the biodiesel industries were used as carbon source for the production of a new extracellular polysaccharide (EPS) by Pseudomonas oleovorans NRRL B-14682. The influence of temperature (20-40 °C) and pH (6.0-8.0) was studied. A temperature of 30 °C and pH control at 6.8 gave the maximum cell growth and EPS production. The culture attained a maximum cell dry weight (CDW) of 9.55 g l^-1 and an EPS concentration of 11.82 g l^-1 when cultivated with pure glycerol. GRP was a suitable carbon source, as shown by the slightly higher EPS concentration (12.18 g l^-1). The EPS productivity obtained with GRP (3.85 g l^-1 d^-1) was almost twice that obtained with pure glycerol (2.00 g l^-1 d^-1). Also, the yield on glycerol was higher for the cultivation with GRP (0.36 g g^-1) than for pure glycerol (0.28 g g^-1). The EPS was a high molecular weight heteropolysaccharide, composed by neutral sugars (37-80 wt% galactose, 2-30 wt% glucose, 0.5-25 wt% mannose and 0.5-20 wt% rhamnose) and containing acyl group substituents (pyruvil, acetyl and succinyl were identified). The EPS forms highly viscous aqueous dispersions with many potential commercial applications.