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The kinetics of growth and xanthan production by Xanthomonas campestris ATCC 1395 in batch culture were studied in a laboratory fermenter without pH control. Fermentations were carried out over a range of stirrer speeds (100–600 rpm) and the pyruvate content, as well as the molecular weight of the product were estimated. Increased agitation levels resulted in higher production rates and biomass levels, while product formation in this fermentation appeared to be partly growth associated. The chemical structure of xanthan was influenced by agitation, as the pyruvate content increased with increasing stirrer speeds. However, no significant effect was observed on xanthan molecular weight as the stirrer speed increased from 100 to 600 rpm.