Title: Prediction of novel carbapenem resistance mechanisms using a P. aeruginosa hypermutator strain in an artificial laboratory evolution experiment (ALE)

Summary:

Pseudomonas aeruginosa was designated a “critical priority pathogen” by the WHO (in 2017) reflecting its ubiquity in the built environment, arsenal of virulence factors, and resistance to multiple antibiotics. A particular threat is the emergence of resistance against carbapenems, which remain a mainstay of antibiotic use globally.

We have an engineered reporter strain of P. aeruginosa (“inducible hypermutator”), its mutation rate can be controlled by the compound rhamnose, which can be tuned from mutation levels 1000-fold higher than wild-type to levels 10-fold lower than wild-type to generate mutant libraries.

The student will work under the guidance of Dr Caray Walker at ARU with some work carried out in Prof Welch’s Group. They will investigate the responses of the reporter P. aeruginosa strain to increasing concentrations of Meropenem (a clinically relevant carbapenem). This will be accomplished by growing the P. aeruginosa in liquid cultures containing increasingly high concentrations of the drug. This is a classic artificial laboratory evolution (ALE) experiment, except both the selection pressure and the genetic diversity of the culture is under experimental control.

The outcome will be to establish P. aeruginosa isolates with increased resistance which will be further analysed by the student using phenotypic assays (e.g. growth and biofilm formation) to determine any fitness costs of the mutations. The location of some potentially interesting resistance mutations will be determined by whole genome sequencing.

Essential knowledge or skills:

Experience in microbiological techniques such as bacterial culture, media preparation would be advantageous.

Supervisors:

Dr Caray A Walker (Anglia Ruskin University, School of Life Sciences): caray.walker@aru.ac.uk

Prof Martin Welch (University of Cambridge, Department of Biochemistry): mw240@cam.ac.uk

Dr Harisree P Nair (Anglia Ruskin University, School of Life Sciences): harisree.paramel-nair@aru.ac.uk