PURPOSE: Specific compounds such as organic acids, organic bases, vitamins and others are added to the fermentation medium containing a carbon source to produce xanthan gum with good viscosity properties, high heat stability and salt resistance.

CONSTITUTION: The fermentation culture medium containing a carbon source used in the cultivation of Xanthomonas campestris NRRL. B-1459 in an aqueous solution containing at least one of carbon sources, nitrogen sources, phosphate salts, and magnesium salts along with at least one selected from organic acids, inorganic bases or vitamins. The culture medium is adjusted in pH to 6.8W7.2, sterilized and cooled. The cultivation is carried out at 25W30°C with aeration for 70W95hr and, after completion of fermentation, a small amount of methanol and water in an amout of 2W5 times the volume of methanol are added to effect dilution. Then, the mixture is subjected to centrifugation to remove cell bodies. Xanthan gum is obtained as a precipitate by adding alcohol and a salt to the resultant mixture.