EFFECT OF SOME PHYSIOLOGICAL FACTORS ON XANTHAN PRODUCTION BY LOCALLY ISOLATED AND IDENTIFIED Xanthomonas campestris USING DATE EXTRACT AS A CARBON SOURCE

Xanthan gum is a microbial polysaccharide that is used in food, medicinal, and industrial applications due to its rheological properties. Using agricultural waste, such as date extract, as a carbon source is a cost-effective way of increase xanthan production. The purpose of this study was to isolate and identify Xanthomonas campestris from different cruciferous plants, as it causes black rot disease. Out of the 100 original bacterial isolates, 19 were selected for PCR analysis after undergoing biochemical and Gram staining. Using gene-specific amplification, only two isolates were identified as Xanthomonas campestris. Cultivation on potato sucrose peptone agar (PSPA), these verified strains displayed mucoid, convex, and yellow colonies that were suggestive of xanthan gum production. The two strains of bacteria were used to produce xanthan gum and to analyze how changes of sugar concentration, incubation period, and nitrogen source affect the bacterium’s ability to produce xanthan. At the end of each experiment, the residual sugar, final pH, xanthan amount, and Biomass were measured. The highest amount of xanthan gum was yielded in 5% date extract medium after 5 days of incubation using 0.12 % di-ammonium hydrogen phosphate as a nitrogen source, and yeast extract 0.3 %. The yields were 0.54 g/100 ml for strain 1 and 1.02 g/100 ml for strain 2 at a shaking incubator agitation rate of 150 rpm of the shaking incubator. This study highlights the importance of controlling physiological parameters to maximize xanthan production from local microbial resources and of synthesizing xanthan on an industrial scale from date extract.