Biosynthesis of xanthan gum from residual glycerin from biodiesel production for drilling fluids

Background Several reports have focused on the value and biological transformation of industrial wastes as an alternative substrate for the production of high value-added components. In this context, it can cite the crude residual glycerin obtained as the primary byproduct of biodiesel production, which has increased exponentially during the last years. As an abundant residue, its disposal into the environment entails several drawbacks and health risks [1]. The bioconversion of this by-product into added-value products by fermentation processes is an important alternative to overcoming this environmental issue. Glycerin is an attractive feedstock for the production of useful chemicals [2], since the cost of the fermentation medium represents, for example, a critical aspect of the commercial production of xanthan, which is the most important microbial polysaccharide with widespread commercial applications (e.g. foodstuffs, pharmaceutical, agricultural products, petroliferous industries) [3], due to its rheological properties and its capacity to produce viscous solutions at low concentrations, together with other characteristics like its pseudoplastic property. This study investigates the effect of glycerin as alternative substrate for xanthan production by Xanthomonas campestris, by evaluating its operational production conditions as well as their physicochemical properties, aiming at its application as drilling fluid.