Response Surface Optimization of Exopolysaccharide Production from Sugarcane Juice by Lactobacillus confusus TISTR 1498

Abstract

Lactobacillus confusus TISTR 1498, isolated from Thai traditional fermented pork (Nham), could secrete large amounts of exopolysaccharides (EPS). Response surface methodology was applied to optimize the culture condi- tions for EPS production using Central Composite Design (CCD). The effects of three variables including pH (4-7), temperature (20-40°C) and nitrogen source (0.25-1.75 PYB) on EPS yield and biomass were investigated. The 1PYB was the mixtures of 5 g/L peptone (P), 2.5 g/L yeast extract (Y) and 2.5 g/L beef extract (B). Response surface methodology showed that the data were adequately fitted to a second-order polynomial model via quadratic regression relationships. The optimal culture conditions for EPS production in sugarcane juice were pH of 5.55, 29.75°C and 1.22PYB, which was composed of 6.1 g/L peptone, 3.05 g/L yeast extract and 3.05 g/L beef extract. Under the optimum condition, the pre- dicted maximum EPS production was 107.5 g/L and the predicted biomass was 1.92 g/L. In submerged fermentation, sugarcane juice enhanced EPS yield twice as well as the modified MRS sucrose medium. In addition, the cost of medium can be lowered to 0.53 THB/g EPS, which was lower than that of the medium from the mixtures of the PYB (0.78 THB/gEPS).