Date of Award

8-23-2024

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biomedical and Chemical Engineering

Advisor(s)

Dacheng Ren

Keywords

Bacteria;Dormancy;HipA toxin;Optogenetics;Persister;Synthetic biology

Subject Categories

Chemical Engineering | Engineering

Abstract

The presence of persister cells makes it difficult to eradicate chronic bacterial infections as these dormant subpopulations arise with exposure to stressors and are capable of surviving antimicrobials that target active cells. Persisters can also revert back to normal growing cells when stressors are removed thus reestablishing the infection. It is therefore important to understand the underlying mechanisms of persister formation, as well as wake-up, and target these systems in order to treat chronic bacterial infections. The formation of persisters, however, remains elusive as there is not yet a clear relationship between the various stages of dormancy. Persister cells can arise while other cells within the population enter a state of deeper dormancy to become no longer viable or culturable on routine media. In this thesis, optogenetic tools were engineered for the spatial and temporal control of persistence with blue and red light control of hipA toxic gene expression in Escherichia coli. Additionally, dynamic dose-dependent dormancy is studied to establish the thresholds at which toxic gene expression results in nonculturable states and states with high persistence to the quinolone ofloxacin. The use of optogenetics allows for reliable experimental set-ups in vivo and is a promising tool for persister generation to test anti-persister therapies.

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Open Access

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