Avaliação da produção de goma xantana por linhagens recombinantes de Xanthomonas campestris pv. campestris

Abstract

Xanthan gum (XG) is a heteropolysaccharide synthesized by bacteria of the genus Xanthomonas through aerobic fermentation. The main characteristics of xanthan gum are its high viscosity, high pseudo-plasticity, great stability of its viscosity in a broad range of temperature and pH and it is compatible with salts. Such properties confer it several applications in food, cosmetics and petroleum industries, since the gum can be used as thickening, emulsifying and stabilizing agents. Nowadays, most of the water-soluble polysaccharides used in the industry come from vegetable sources, but, even though Brazil depends on its import, microbial polysaccharides proved to be of large commercial value. The development of processes for the gum synthesis has been oriented in the sense of optimizing factors such as operational conditions, growth media and technologies for recovering the intended composite – and an important part of this process is the development of new recombinant strains that optimizes the gum production. In this context, Oliveira (2021) did the overexpression of the top enzymes targeted as bottlenecks on the synthesis pathway of XG, UDP-glucose dehydrogenase (UDPG-deH) and UDP-glucose pyrophosphorylase (UDPG-PP) in the strains of Xanthomonas campestris pv. campestris and noticed a significant improvement on the production of xanthan when the enzymes are individually overexpressed and under certain conditions. The present work aims to re-evaluate the aforementioned results by using recombinant strains of Xanthomonas campestris pv. campestris on which the ugd (which codifies the UDPG-deH enzyme) and galU (UDPG-PP) genes were cloned and transformed based on a broad-spectrum vector of hosts. Two plasmids, each containing one of the genes, were used in order to measure whether or not their overexpression contributes to an increase in gum productivity and it was observed that the use of recombinant strains, along with further growth parameters, can promote the xanthan gum volumetric productivity through Xanthomonas cells.