2-37: The effect of raw glycerol discharged after biodiesel manufacturing in the xanthan gum production synthesized by Xanthomonas isolated in Brazil

The cultural conditions for xanthan gum production by three strains of the Xanthomonas sp isolate in Brazil were investigated and optimized by response surface methodology, to maximize xanthan production in batch experiments using a synthetic broth (MPI+II) and glycerol. The individual and interactive effects of three independent variables (substrate concentration (glycerol and sucrose )  (0 – 100%), agitation rate (180-250 rpm), time of cultivation (72–120 h)) on xanthan gum and biomass production were studied, using a face-centered composite design of experiments. Overall optimization allowed us to point out an optimal range of the three independent variables. Experimental design methodology were performed and the maximum productivity obtained was 0.331 g/L.h. The viscosity analysis was performed for aqueous solutions 3%, at 25, 45 and 60ºC. The polysaccharides synthesized in media with glycerol and sucrose was largely indistinguishable from xanthan gum produced only glycerol. The rheology (apparent viscosity) presented similar values compared to those of the literature for other biopolymers.