Avaliação de vetores de expressão para Xantomonas ssp. aplicados à produção de goma xantana

Abstract

Xanthomonas sp. are proteobacteria widely known for its pathogenic association with varied species of plants, such as Xanthomonas campestris, which causes black rot that affects crucifers. Its pathogenicity is partially supported by the production of a biofilm that has high viscosity, xanthan gum. This biopolymer has properties that allow it to complement natural and synthetic water-soluble gums, presenting emulsifying and thickening activity, showing great appreciation for several industry sectors. Unfortunately, Brazil doesn’t have a national production of the compound, being totally dependent on imports. To make the gum production process more attractive and efficient, it is highly relevant to enter the field of development of optimized strains, which is being little explored. Contributing to change this scenario, Kundlascht (2017) developed a deterministic mathematical model that encompasses the reactions for the synthesis of xanthan gum monomers, and from it was able to identify a bottleneck in this pathway with the reactions catalyzed by the enzymes UDPGlucose pyrophosphorylase (UDPG-PP) and UDP-Glucose dehydrogenase (UDPGdeH). With these results obtained in silico, the present work sought to validate this hypothesis in vivo, cloning the genes for the enzymes UDPG-PP and UDPG-deH in very versatile vectors used for the construction of metabolic pathways, belonging to the ePathBrick vectors collection, based on the Biobrick. Initially these plasmids showed promise for use in the chassis of Xanthomonas campestris sub. campestris (XCC), but throughout the experiments they were not functional in the bacterium. From this results, new objectives were set, resulting in the proposal to construct plasmids for use in XCC while maintaining the versatility of the ePathBrick vectors backbone.