Xanthan is used as stabilizer, thickener, and water mobility reducer in industries as different as food and petroleum. The medium expenses are about one third of its production costs. Utilization of alternative carbon sources, like food industry waste, could reduce xanthan production costs. A potato processing plant generates waste in amounts as high as 25% of its processing capacity.

Xanthan fermentation was conducted on potato waste in solid and semi-solid mode. The individual and interactive effects of: i) enzymatic pre-treatment, ii) mechanical pre-treatment, iii) pH control, and iv) control of moisture content on xanthan production and substrate utilization were analyzed using response surface methodology.

Xanthomons campestris NRRL 1003 strain produces on average sixty percent more xanthan than NRRL 1013 strain which consumed on average 6% more substrate than NRRL 1003 strain. Xanthomons campestris NRRL 1459B strain fermented on average 22% less xanthan than NRRL 1003 strain; these two strains consumed roughly equal amount of potato waste during 96 hours fermentation. All three strains produced more xanthan on solid potato waste medium than on 2% glucose medium. Xanthan fermentation on solid potato waste could compete with xanthan fermentation on standard glucose medium since medium related expenses are at least 20% smaller on the potato waste medium.