Optimization of the EPS production of a bacterial floc consortium using different parameters

The capacity for exopolysaccharide (EPS) biosynthesis of a bacterial consortium culture was investigated. To obtain maximal EPS recovery, pH, carbon and nitrogen sources, and inorganic ions were optimized. At pH 8, the flocculation index (FI) percentage was 62.6%, viscosity was 1.38 +/- 0.015 g m(-1).s(-1), and 10.3 g/L EPS was produced. However, the maximum total EPS production (12 g/L), FI percentage (70%), and viscosity (1.4 +/- 0.01 g m(-1).s(-1)) were achieved when ammonium sulfate was used as nitrogen source. Meanwhile, the highest EPS production was realized when dextrose was selected as carbon source with and without crude oil. Dextrose exhibited significant advantage over the four other carbon sources. After 5 days of incubation with crude oil, the dextrose enhanced EPS production to (14 g/L) with a high FI percentage (70.7%). Among the inorganic ions, the maximum EPS production (16.1 g/L) was obtained after adding 0.5% potassium chloride to the culture medium, with a high viscosity of 1.44 +/- 0.005 g m(-1).s(-1).