Effect of carbon sources on xanthan production by Xanthomonas spp. isolated from pepper leaves

Xanthan is the most important microbial exopolysaccharide used in different branches of food and non-food industry. Due to high consumption of glucose and sucrose, usually utilized carbon sources in many bioprocesses, the most prominent research in xanthan production is related to the isolation of new xanthan producing strains capable to metabolize other carbon sources and to produce xanthan with characteristics appropriate for usage in food industry. The aim of this study was to examine the effect of variation of carbon sources in cultivation media on xanthan production by reference strain Xanthomonas campestris ATCC 13951 and five Xanthomonas strains isolated from infected pepper leaves. Bioprocess efficacy was estimated based on the quantity and quality of biosynthesized xanthan. The obtained results show that both, the selection of the carbon source and selection of producing strain have a statistically significant effect on bioprocess efficacy whereby the influence of carbon sources on the analyzed parameters is more pronounced. It was confirmed that Xanthomonas strains responsible for the production of a large amount of xanthan are not suitable for biosynthesis of good-quality biopolymer. Taking into account all results it can be concluded that the greatest potential in biotechnological xanthan production has strain PFNS PL4 and glucose or starch containing media which is the basis for further research.