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The opportunistic pathogen, Burkholderia cenocepacia, mainly infects people with cystic fibrosis and is a problem in these patients due to its high intrinsic resistance to antimicrobials and unpredictable disease severity. In this study, we have investigated the B. cenocepacia phosphate stress response and assessed its effect on membrane lipid remodelling. Firstly, a putative Pho regulon for B. cenocepacia has been characterised using comparative proteomics. Using lipidomics, it was discovered B. cenocepacia was able to produce glycolipids in phosphate deplete conditions. Lipid remodelling has been shown in previous studies to occur under phosphate stress through the phospholipase, PlcP. We identified a putative homolog for PlcP in Burkholderia species and generated a plcP deletion mutant in B. cenocepacia (K56-2ΔplcP). Under phosphate deplete conditions, K56-2ΔplcP was unable to produce glycolipids, and complementation of this mutation resulted in the restoration of glycolipid production. To examine whether PlcP was involved in virulence, the Galleria mellonella infection model was used which showed K56-2ΔplcP was significantly less virulent than wild-type B. cenocepacia. Assessing the bacterial survival of K56-2ΔplcP within the insect model demonstrated K56-2ΔplcP was unable to replicate within hemocytes, unlike wild-type B. cenocepacia. Overall, this project has begun to unravel the lipid remodelling response to phosphate limitation in B. cenocepacia and its phenotypic effect on virulence. Further research into the phosphate stress response of Burkholderia species may reveal new therapeutic targets and strategies for this genus of bacteria. |
