Industrial Culture Medium Optimization of Xanthan Gum Production (Xanthomonas campestri) by RSM Simplified

Xanthan gum shows pseudoplastic behavior in solutions, and has less ‘gummy’ mouth feel than Newtonian ones. Therefore, xanthan gum has major application in food industry as a thickening and suspending agent. Xanthan gum is a bacterial gum and the production process is largely affected by the culture medium compositions. The aim of this study was to optimize an economic industrial medium for maximum yield of xanthan gum.
Xanthan gum production by Xanthomonas campestris ATCC 1395 using different culture medium was carried out in a stirred bioreactor with controlled pH and dissolved oxygen. A fractional factorial design was applied to identify the effective factors on xanthan gum production. Central composite design and response surface methodology were used to evaluate the individual and interactive effects of four major significant variables (glucose, sucrose, yeast extracts and (NH4)2SO4) on biomass and xanthan gum production in submerged culture medium composition.
The results indicated that both carbon and nitrogen sources had strong positive effects on xanthan gum production, but the carbon source, especially glucose, was determined to be more significant factor than nitrogen source in growth cell and production of gum. theoptimum culture medium for producing xanthan gum was composed of 53.75 (g/L) glucose, 27.8 (g/L) sucrose, 7.8 yeast-extract (g/L) and 5.6 (NH4)2SO4 (g/L). After 36 hours under the optimized culture medium in 5-L bioreactor the xanthan gum yield reached about 12.26±0.44 g/L, which was found to be in good agreement with the predicated value (12.43 g/L).
The optimized culture medium studied here can be a good candidate to improve the yield and consequently be more cost-effective in the production of xanthan gum.