Optimization of exopolysaccharide production from the novel Enterococcus species, using statistical design of experiment.

Abstract

The Exopolysaccharide (EPS) producing novel strains of Enterococcus previously isolated from the vaginal source of pregnant women were selected based on ropy structure formation. The two selected strains, E.villorum SB-2 and E.rivorum S22-3, were found to be producing 2.87 g/l and 3.14 g/l EPS, respectively, in the minimal media (M17 media) after 24-hour fermentation under anaerobic condition. Both the strains have probiotic properties and have the potential to be used for industrial applications. The production media and fermentation conditions were optimized to enhance the EPS production using the one-factor method, Placket-Burman factorial designing and Central composite design (CCD) of Response surface methodology (RSM). The most relevant factors affecting the EPS yield were sucrose, yeast extract and pH for E.villorum SB2 and sucrose, yeast extract and magnesium sulfate for the E.rivorum S22-3 as determined by Placket-Burman design, whose concentrations were further optimized using CCD. The optimized fermentation conditions gave the total EPS of 9.76 g/l (4 times the initial production) from E.villorum SB-2 and 7.74 g/l (2.5 times the initial production) from E.rivorum S22-3, respectively, after 36-hour incubation at 37 °C. These optimization studies might be helpful during scale-up process for the industrial scale production of these exopolysaccharide.