Abstract
The present study emphasizes improving the overall yield, productivity and quality of xanthan by Xanthomonas campestris using different carbon sources via optimizing the fermentation media and kinetic modelling work. After optimization, six carbon sources and one nitrogen source were selected for xanthan production in 5 L bioreactor. Kinetic modelling was applied to assess the experimental fermentation data and to check its influence on scale-up production. In this work, xanthan production reached 40.65 g/L with a growth-associated rate constant (α) of 2.831, and highest specific growth rate (μm) of 0.37/h while using maltose as the sole carbon source. Furthermore, rheological properties were determined, and Herschel-Bulkley model was employed to assess the experimental data. Interestingly, xanthan obtained from sucrose and glucose showed the highest yield stress (τ0) of 12.50 ± 0.31 and 7.17 ± 0.21. Moreover, the highest xanthan molecular weight of 3.53 × 107 and 3.25 × 107 g/mol were also found with sucrose and glucose. At last, the proposed mechanism of sugar metabolism and xanthan biosynthesis pathway were described. Conclusively, maltose appeared as the best carbon source for maximum xanthan production: while sucrose and glucose gave qualitatively best results. In short, this systematically modelled approach maximizes the potential output and provides a solid base for continuous cultivation of xanthan at large-scale production.
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•Kinetic modelling was proposed for xanthan production with six different carbon sources.•Highest xanthan production of 40.65 g/L (with μm = 0.37/h) was achieved under maltose.•Herschel-Bulkley model was used to assess the experimental rheological data.•Acetate and pyruvate content influenced the viscosity and molecular weight of xanthan.•Highest xanthan molecular weight of 3.53 × 107 g/mol was found under sucrose.