Production and characterization of the polysaccharide ‘’xanthan gum’’ by a local isolate of the bacterium Xanthomonas campestris

Abstract

A local isolate of the bacterium Xanthomonas campestris was obtained from infected cabbage leaves. Microbiological and biochemical tests were made to confirm its identification. The isolate was coded as X. campestris MU1. Growth and xanthan production reached their highest levels (1.65 and 5.41 g/l) after 7 and 8 days of incubation, respectively, in a chemically defined medium. Sucrose was shown to be the best carbon source for xanthan production. Thin layer chromatography of the produced xanthan showed that, it composed glucose, mannose and glucouronic acid, in addition to pyruvic and acetic acids. The results indicate that, X. campestris MU1 is very much related to X. campestris NRRL-B 1459.

Key words: Xanthomonas campestris, xanthan gum, microbial polysaccharides.