Detection of Xanthomonas campestris mutants with increased xanthan production

Abstract

Several mutants of Xanthomonas campestris showing increased viscosity and/or gum production were detected after UV treatment. Xanthan solutions of the different mutants showed different intrinsic viscosity values, and no relationship was found between pyruvate or acetate contents and viscosifying ability of the xanthan. The best performance mutant (M-11) was obtained using halo size around colonies in starch-agar plates as the detection criterion, and proved the usefulness of this indirect screen for improved xanthan producers. A pleiotropic effect of this mutation on growth rate and total cell growth was observed.