Synthesis of Xanthan Gum from Xanthomonas campestris Immobilized in Polyurethane

Xanthan gum, a biopolymer produced by the bacteria Xanthomonas campestris, with varied applications in many industrial branches. Cell immobilization is an alternative to enhance xanthan gum production, reducing both time and costs, while increasing yield. The present study sought to immobilize the microorganism Xanthomonas campestris in situ in polyurethane. The immobilization process was carried out in a mixture of polyol and isocyanate. The immobilization, as well as the storage stability of the immobilized cells and the capacity for recycling, was evaluated by the production of xanthan gum and cell leakage from the matrix. According to the results, the immobilization process increased xanthan gum production by 274%. The continuous batch fermentations demonstrated the possibility of reusing the immobilized cells up to 6 times, considering 50% of the initial xanthan gum production. Storage in different temperatures −4°C, −4°C, and −80°C—for thirty days did not affect the metabolic capacity of the immobilized cells to produce xanthan gum, although storage in −80°C showed higher xanthan gum production and lower cell leakage from the matrix.