Purpose: The objective of this study was to investigate the role of aerobic desaturase, DesB in stress responses of P. aeruginosa.
Methods: P. aeruginosa PAO1 (wild type; WT) and its derived mutants (harboring a mutation in desB, desT, desA, or fabA) were used to determine if the genes, associated with UFA synthesis, are responsible for the adaptation to hostile conditions. The cultures were exposed to oxidative, osmotic or acidic stress, and the bacterial growth was observed. To elucidate the underlying mechanism of DesB on stress response, transcriptional levels of WT and desB mutant were compared using qRT-PCR.
Results: The growth of P. aeruginosa WT and its derived mutants displayed no difference regardless of exposure to oxidative or acidic condition. Also, the bacterial strains showed similar growth in the presence of 0.2 M NaCl, whereas their growth was inhibited slightly or severely under the exposure of 0.5 or 1.0 M NaCl, respectively. More importantly, desB mutant exhibited more impaired growth than WT and other mutants under these high concentrations of NaCl, suggesting the role of DesB on osmotic stress. Transcriptional analysis revealed that genes associated with osmoprotectant synthesis were highly expressed in response to NaCl in WT, but rarely expressed in desB mutant.
Significance: The results demonstrate that P. aeruginosa DesB has an important role in resistance and adaptability to osmotic stress through affecting the expression of osmoprotectant synthesis genes.