Optimization of xanthan gum production using cheese whey and response surface methodology

Cheese whey lactose was used as a carbon source for xanthan gum production with Xanthomonas campestris and Xanthomonas pelargonii. Proteins were precipitated and removed from whey prior to fermentation. Box-Behnken response surface methodology was used for optimization of the carbon, magnesium, and phosphate source concentrations in the culture medium to maximize xanthan gum production. After 48 h of fermentation using X. campestris, the highest xanthan concentration (16.4 g/L) was achieved at 65.2 g/L of cheese whey (39.1 g/L of lactose), 14.8 g/L of phosphate (K H2PO4), and 1.1 g/L of magnesium (MgSO4 center dot 7H(2)O). The corresponding optimum cheese whey, phosphate, and magnesium concentrations in cultures of X. pelargonii were 80.0, 6.7, and 0.8 g/L, respectively, which resulted in a xanthan production of 12.8 g/L. The xanthan gum yield (g of xanthan/g of lactose) was 0.42 for X. campestris and 0.27 for X. pelargonii.