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

► First report of optimization and antioxidant activity of an EPS by P. fluorescens. ► The EPS was composed of arabinose, glucose and uronic acid. ► Maltose, Zn2+ and Mn2+ were found important factors for its optimum production. ► Good H2O2 scavenging while moderate free radical scavenging and reductive ability. ► The EPS can be a new source of natural antioxidants.