Understanding the Role of Anaerobic Respiration in Burkholderia Thailandensis and B. pseudomallei Survival and Virulence
Andreae, Clio A.
Date: 2 May 2014
University of Exeter
PhD in Biological Sciences
Burkholderia pseudomallei is the causative agent of melioidosis, a disease endemic in Northern Australia and Southeast Asia. Melioidosis can present with acute, chronic and latent infections and can relapse several months or years after initial presentation. Currently not much is known about the ways in which B. pseudomallei can persist ...
Burkholderia pseudomallei is the causative agent of melioidosis, a disease endemic in Northern Australia and Southeast Asia. Melioidosis can present with acute, chronic and latent infections and can relapse several months or years after initial presentation. Currently not much is known about the ways in which B. pseudomallei can persist within the host, although it has been speculated that the ability to survive within an anaerobic environment will play some role. B. pseudomallei is able to survive anaerobically for extended periods of time but little is known about the molecular basis of anaerobic respiration in this pathogenic species. Bioinformatic analysis was used to determine the respiratory flexibility of both B. pseudomallei and B. thailandensis, identifying multiple genes required for aerobic and anaerobic respiration, and molybdopterin biosynthesis. Using B. thailandensis as a model organism a transposon mutant library was created in order to identify genes required for anaerobic respiration. From this library one transposon mutant was identified to have disrupted moeA, a gene required for the molybdopterin biosynthetic pathway. This B. thailandensis transposon mutant (CA01) was unable to respire anaerobically on nitrate, exhibiting a significant reduction in nitrate reductase activity, altered motility and biofilm formation, but did not affect virulence in Galleria mellonella. It was hypothesised that the reduction in nitrate reductase activity was contributing to the phenotypes exhibited by the B. thailandensis moeA transposon mutant. To determine whether this was true an in-frame narG deletion mutant was created in B. pseudomallei. Deletion of B. pseudomallei narG (ΔnarG) resulted in a significant reduction in nitrate reductase activity, anaerobic growth, motility and altered persister cell formation, and but did not affect virulence in G. mellonella or intracellular survival within J774A.1 murine macrophages. This study has highlighted the importance of anaerobic respiration in the survival of B. thailandensis and B. pseudomallei.
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