Engineering probiotic lactic acid bacteria for biomedical applications
Bober, Josef.
2019
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Correlations between
the composition of the human microbiota and health status have sparked a rapidly growing
interest in the intertwined complexities associated with these commensal microbial
species. Large datasets of genetic, metabolic, proteomic etc. information can be
generated through metagenomic and metatranscriptomics approaches rather easily; however,
to elucidate the commensal ... read moremechanisms and benefits of these fastidious organisms, novel
engineering techniques must accompany those observational measurements. Firmicutes, of
which lactic acid bacteria (LAB) are members, make up the largest proportion of the
human microbiota, yet few species are genetically tractable. Given their inherent safety
and decades of food science research for fermentation processes, lactic-acid bacteria
are ideal candidates for engineering novel biochemical production strains and the
creation of living therapeutics for biomedical applications. In this work, we initially
demonstrate the benefits of using Lactobacillus plantarum encapsulating the enzyme
L-arabinose isomerase to overcome the thermodynamic, kinetic, and stability issues
associated with galactose isomerization for tagatose production. We initially
demonstrated the limitations to free-enzyme catalysis; challenging the traditional
improvement approach of protein engineering, and systematically overcame each hurdle
using a mesophilic enzyme encapsulated by a food-safe bacterium in a batch process
resulting in the highest reported bioconversion. Next, we sought to engineer L.
plantarum to rapidly sequester dietary lactose and galactose as a living therapeutic to
remediate the toxicity of patients diagnosed with the rare genetic disorder
galactosemia. Through this development, we studied the ability of L. plantarum to
surface display heterologous proteins and enhanced the species ability to transport and
metabolize carbohydrates. Overall, this thesis describes leveraging the beneficial
probiotic properties of lactic acid bacteria for biomedical applications and emphasizes
the need further improve upon currently available genetic tools to advance future
applications.
Thesis (Ph.D.)--Tufts University, 2019.
Submitted to the Dept. of Chemical and Biological Engineering.
Advisor: Nikhil Nair.
Committee: Kyongbum Lee, Benjamin Wolfe, and Kristala Prather.
Keywords: Bioengineering, and Chemical engineering.read less - ID:
- 2z10x348j
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