Variations in the Adaptive Response of <i>Burkholderia pseudomallei</i> to Cold Stress

Abstract

The aim of the study was to analyze differential gene expression in Burkholderia pseudomallei strains with different survival rates under cold stress conditions.Materials and methods. Three strains of B. pseudomallei (sequence types ST 46, ST 70, and ST 85) were used as model strains. The RNA was isolated using the membrane columns method and stabilized through dehydration. The cDNA was sequenced on the Illumina MiSeq platform. Gene functions were classified using the KEGG PATHWAY database.Results and discussion. Based on the analysis of transcriptomes of B. pseudomallei strains after prolonged exposure to cold stress, the molecular mechanisms of B. pseudomallei adaptation to low temperatures have been described for the first time ever. It was shown that adaptation of B. pseudomallei to cold stress is associated with regulatory processes leading to a significant decrease in the total transcriptional activity. Two strategies of adaptation to low temperatures have been found: 1) modulation of regulatory processes leading to suppression of gene expression of the main metabolic pathways to the minimum level that ensures cell viability and activation of the minimum required set of stress response genes, and 2) less noticeable suppression of general metabolism in combination with activation of expression of an extended range of genes for cold and heat shock, general, osmotic, and universal stresses. Both mechanisms provide the causative agent of melioidosis with survival under conditions of prolonged cold stress at low positive temperatures. The first strategy showed greater efficiency at negative temperatures. The transition of B. pseudomallei to a viable but uncultivated state occurs in the long term (at least 2 years). While with the second strategy, this happens within 2 months. Assessment of the potential and molecular mechanisms of adaptation of this bacterium to cold stress is necessary to understand the degree of risk in case of a possible introduction of B. pseudomallei into regions with a temperate climate and to develop effective measures to ensure the biosafety of the environment.