Fed-batch fermentation for rapid production of xanthan by Xanthomonas campestris

The object of the present work was to optimise inoculum size and nitrogen source for rapid production of xanthan by Xanthomonas campestris by fed-batch fermentation. The fermentation period for production of xanthan by X. campestris decreased from 72 h to 48 h by using 30% (v/v) inoculum instead of the usual 10% level. Among various nitrogenous substances tested in the medium having the C/N ratio of 28, the best concentration of 1.9% (w/v) of xanthan with a viscosity of 10,000 cP was obtained for KNO3 medium. Intermittent harvests operated for three cycles of 48 h each, using 30% inoculum. resulted in xanthan broth of high viscosity (9000 cP) with a concentration of 1.9% and a yield of 68% (w/w). Potassium nitrate was a better suited nitrogen source for the medium used for rapid production of xanthan.