Abstract: Xanthan gum is categorized to be an exospore heteropolysaccharide in cultures of Xanthomonas campestris during fermentation in carbohydrates (corn starch) as main substrate. In order to improve xanthan gum productivity, the effects of adding oxygen-vectors (alkane mixture) on xanthan fermentation were studied. Also, the strains were observed at different fermentation time under transmission electron microscope (TEM). When cultivated for 66 h by addition of 8% alkane mixture, xanthan gum yield and transformation rate of carbon source were obviously increased. By means of the shaking flask testing the results were 3.84% and 76.8% for the gum productivity and transformation rate respectively (control, 2.58% and 51.6%, respectively), whereas in the fermentor testing those were 4.18% and 83.6% respectively (control, 2.90% and 58.0%, respectively).

Key words: xanthan gum, alkane mixture, X.campestris