Optimization and characterization of a polysaccharide produced by Pseudomonas fluorescens WR-1 and its antioxidant activity

The extracellular polysaccharide produced by a newly isolated strain Pseudomonas fluorescens WR-1 was purified and characterized and its production was optimized using response surface methodology. The results showed that the strain WR-1 produced one kind of EPS that was composed of arabinose, glucose and uronic acid. The molecular weight of the EPS was determined to be 6.78 × 106 Da. The preferable culture conditions for EPS production were pH 7.0, temperature 28 °C for 72 h with peptone and maltose as best N and C sources, respectively. The model predicted that the maximum EPS production (39.6 g L−1) was appeared with maltose 48.65 g L−1, Mn2+ 1118 μM and Zn2+ 901 μM. The EPS also showed good H2O2 scavenging activity while moderate free radical scavenging activity and reductive ability were determined. The EPS from WR-1 may be a new source of natural antioxidants with potential value for health, food and industry.