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 9.55gl−1 and an EPS concentration of 11.82gl−1 when cultivated with pure glycerol. GRP was a suitable carbon source, as shown by the slightly higher EPS concentration (12.18gl−1). The EPS productivity obtained with GRP (3.85gl−1d−1) was almost twice that obtained with pure glycerol (2.00gl−1d−1). Also, the yield on glycerol was higher for the cultivation with GRP (0.36gg−1) than for pure glycerol (0.28gg−1). The EPS was a high molecular weight heteropolysaccharide, composed by neutral sugars (37–80wt% galactose, 2–30wt% glucose, 0.5–25wt% mannose and 0.5–20wt% rhamnose) and containing acyl group substituents (pyruvil, acetyl and succinyl were identified). The EPS forms highly viscous aqueous dispersions with many potential commercial applications.