Effect of the nitrogen source on pyruvate content and rheological properties of xanthan

Batch and fed batch cultivations of Xanthomonas campestris with varying amo unts of the N source (NH4Cl) yield xanthan polymers which differ in pyruvat e content. Analyzing the rheological properties of the xanthans produced ex hibits that it is not only the molecular mass but also the pyruvate content that affects the viscosity of xanthan solutions. However, there is obvious ly no simple functional dependency but rather a step increase in viscosity when going from below 2 to above 3 wt % of pyruvate.