Influence of strain and fermentation time on the production, composition, and properties of xanthan gum

The objective of this study was to monitor the influence of Xanthomonas spp. and fermentation time on the production, properties, and composition of xanthan gum, verifying how these variables affect the biopolymer synthesis and properties. Three strains were monitored for 168 h of fermentation. Every 24 h, a sample was collected to determine cell growth, gum production, and substrate consumption. Fourier transform infrared, X-ray diffraction, rheology, molecular characterization, thermogravimetric analysis, sugars, and acids analyzes were performed to characterize the gums produced and to identify possible differences in these properties and composition. The results showed the influence of strain and the fermentation time in production (Pr-645 = 0.047 g L-1 h(-1), Pr-290 = 0.039 g L-1 h(-1), Pr-1155 = 0.149 g L-1 h(-1)) and gum quality, since the viscosity was highest in the first 48 h for strains 290 (148.71 MPa s(-1)) and 645 (135.28 MPa s(-1)), while for Strain 1155, the maximum value identified for this property was 90.48 MPa s(-1). These results are of practical importance, since they allow obtaining better quality xanthan, enabling reduction of production costs. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48557.