SRA

The two component regulatory system is a global signal transduction system highly conserved and responsible by the microorganisms to adapt to changing environments in response to environmental signals. This system controls the adaptation to several stress conditions in pathogenic or symbiotic interactions with different hosts or with the environment. Burkholderia seminalis TC3.4.2R3, belonged to Burkholderia cepacia complex (Bcc), has been drawing great attention to be used as biological control agent due to its ability to inhibit several phytopathogenic fungi and bacteria species. In this study, a mutant in a two component system was obtained and evaluated in comparison to the wild type using different approaches (molecular, phenotypic and physiologic analysis). The transcriptome analysis (RNASeq) revealed 374 differential expressed genes (DEGs) being 188 up-regulated and 186 down-regulated. The mutation in the two component system from B. seminalis TC3.4.2R3 determined the regulation of the genes mainly involved in the motility and chemotaxis (down-regulated in the mutant); and related to iron uptake and pyochelin siderophore production (up-regulated in the mutant). To validate these results, different experimental assays were carried out. The mutation determined a significant difference in the growth profile between the strains since the mutant grew faster and started its stationary phase first; however, the wild type grew more and died before. The swarming and swimming motility assays were impaired in the mutant and the biofilm production increased. The two component system seems to be positively regulating genes involved directly or indirectly in the acetoacetic acid metabolism and negatively regulating genes involved in the Gelatin, Dextrin and D-Fucose utilization in B. seminalis TC3.4.2R3 wild type. Biocontrol efficacy against fungus and bacteria species was similar. These findings highlight that the two component regulatory system in focus positively regulates the motility and chemotaxis genes and negatively controls the genes related to biofilm production, iron uptake and pyochelin siderophore production in the B. seminalis TC3.4.2R3 wild type, being all these functions directly involved in the colonization, competition, interaction and survive of this strain in different hosts or environments.