Construction and application of a Xanthomonas campestris CGMCC15155 strain that produces white xanthan gum

Abstract

In the industrial production of xanthan gum using Xanthomonas campestris CGMCC15155, large amounts of ethanol are required to extract xanthan gum from the fermentation broth and remove xanthomonadin impurities. To reduce the amount of ethanol and the overall production cost of xanthan gum, a xanthomonadin-deficient strain of CGMCC15155 was constructed by inserting the Vitreoscilla globin (vgb) gene, under the control of the LacZ promoter, into the region of the pigA gene, which is involved in xanthomonadin synthesis. The insertion of vgb inactivated pigA, resulting in the production of white xanthan gum. The lack of xanthomonadins resulted in a decreased yield of xanthan gum. However, the expression product of vgb gene, VHb, could increase the metabolism of X. campestris, which allowed the production of xanthan gum to reach wild-type levels in the engineered strain. The yield, molecular weight, and rheological properties of the xanthan gum synthesized by the engineered and wild-type bacteria were essentially the same. When the same volume of ethanol was used, the whiteness values of the xanthan gum extracted from engineered and wild-type bacteria were 65.20 and 38.17, respectively. To extract xanthan gum with the same whiteness, three and seven times the fermentation volume of ethanol was required for the engineered and wild-type strains, respectively. Thus, the engineered train reduced the requirement for ethanol in xanthan gum production by 133.3%. The results demonstrated that the engineered bacteria used less ethanol, thus reducing the downstream processing cost in xanthan gum production.

Bacterial spot caused by Xanthomonas vesicatoria devastated tomato production of Khyber Pakhtunkhwa-Pakistan

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Water‐soluble polymers in agriculture: xanthan gum as eco‐friendly alternative to synthetics

“…Regarding production optimization, it has also been found that xanthan gum molecular properties such the substitution pattern with acetyl and pyruvate groups and thus rheological behaviour can be fine‐tuned on a genetic level (Gansbiller et al ., 2019). Strain genetic engineering also proved feasible to increase whiteness of the xanthan gum product while using lower amounts of ethanol in the downstream processing (Dai et al ., 2019). However, on an industrial scale, this approach may be prohibitive due to regulatory compliance and product labelling.…”

Xanthan gum in drug release

“…The FDA approved xanthan gum as a safe polymer in the food industry in 1969; thus, the xanthan products can be found in four grades: crude, industrial, food, and medical auxiliary (28). Despite its high molecular weight (regularly between 2 x 10 6 to 20 x 10 6 Da), the xanthan gum is soluble in cold and hot water, and ethanol, but in this case, intense stirring is needed for dismiss agglomeration.…”