BIOCONVERSION FROM CRUDE GLYCERIN BY Xanthomonas campestris 2103: XANTHAN PRODUCTION AND CHARACTERIZATION

The production and rheological properties of xanthan gum from crude glycerin fermentation, a primary by-product of the biodiesel industry with environmental and health risks, were evaluated. Batch fermentations (28 degrees C/250 rpm/120 h) were carried out using crude glycerin, 0.01% urea and 0.1% KH2PO4, (% w/v), and compared to a sucrose control under the same operational conditions, using Xanthomonas campestris strain 2103 isolate from Brazil. Its maximal production by crude glycerin fermentation was 7.23 +/- 0.1 g.L-1 at 120 h, with an apparent viscosity of 642.57 mPa.s, (2 % w/v, 25 degrees C, 25 s(-1)), 70% and 30% higher than from sucrose fermentation, respectively. Its molecular weight varied from 28.2 to 36.2x10(6) Da. The Ostwald-de-Waele model parameters (K and n) indicated a pseudoplastic behavior at all concentrations (0.5 to 2.0%, w/v) and temperatures (25-85 degrees C), while its consistency index indicated promising rheological properties for drilling fluid applications. Therefore, crude glycerin has potential as a cost-effective and alternative substrate for non-food grade xanthan production.