Optimization of Cultural Conditions for Production of Extracellular Polysaccharide by Halomonas xianhensis SUR308 Using Weighted Response Surface Methodology

Abstract

Optimization of different physico-chemical and cultural parameters such as temperature, pH, incubation time and inoculum dose along with variation of NaCl, glucose and casein hydrolysate concentrations were carried out in the present investigation for the enhancement of extracellular polysaccharide (EPS) production by Halomonas xianhensis SUR308. Weighted response surface methodology (WRSM) was applied to study the interactive effects of these seven significant variables on EPS production by the isolate. A second order polynomial regression model for weighted response of the growth (O. D. at 540 nm) and production of EPS (g/L) was used to analyze the experimental data following the analysis of variance (ANOVA). Such analysis showed that the model was very significant (p < 0.05). Interaction among glucose, NaCl and pH was found to be most effective for growth and EPS production by H. xianhensis SUR308. The estimated optimum conditions of these variables obtained by using desirability function were 3.49% glucose, 2.5% NaCl and pH 6.8. Under such conditions the isolate produced 7.8 g/L of EPS which justify the predicted value (7.45 g/L) of EPS production in WRSM.