Programming microbes to treat superbug infection
Wong, Adison Choon Kit
Date of Issue2016
School of Chemical and Biomedical Engineering
Superbug infection is one of the greatest public health threat with grave implications across all levels of society. Towards a new solution to combat infection by multi-drug resistant bacteria, this thesis presents an engineering framework and genetic tools applied to repurpose commensal bacteria into "micro-robots" for the treatment of superbug infection. Specifically, a prototype of designer probiotic was developed using the human commensal bacteria Escherichia coli. The engineered commensal was reprogrammed with user-specified functions to sense superbug, produced pathogen-specific killing molecules and released the killing molecules via a lytic mechanism. The engineered commensal was effective in suppressing -99% of planktonic Pseudomonas and preventing - 90% of biofilm formation. To enhance the sensing capabilities of engineered commensal, genetic interfaces comprising orthogonal AND & OR logic devices were developed to mediate the integration and interpretation of binary input signals. Finally, AND, OR and NOT logic gates were networked to generate a myriad of cellular logic operations including half adder and half subtracter. The creation of half adder logic represents a significant advancement of engineering human commensal to be biological equivalent of microprocessor Chips in programmable computer with the ability to process input signals into diversified actions. Importantly. this thesis provides exemplary case studies to the attenuation of cellular and genetic context dependent effects through principles elucidated herein, thereby advancing our capability to engineer commensal bacteria.