In partial fulfillment of the requirements for the degree of
Master of Science in Biology
in the
School of Biological Sciences
MARGARET WARNER
Will defend her thesis
“SINGLE-CELL ENCAPSULATION OF NON-SPORE FORMING PROBIOTIC BACTERIA FOR INCREASED SURVIVABILITY UNDER ENVIRONMENTAL EXTREMES”
11 November 2024
11 AM
https://gatech.zoom.us/j/97407560960?pwd=1g01kbQShILVARKw4HuEn5IpzPpLW3.1
Thesis Advisor:
Dr. Jie Xu
Georgia Tech Research Institute
Georgia Institute of Technology
Committee Members:
Dr. Mark Hay
School of Biological Sciences
Georgia Institute of Technology
Dr. Francesca Storici
School of Biological Sciences
Georgia Institute of Technology
Abstract:
Spore-forming bacterial cells possess extensive capabilities to survive extreme environmental conditions for an extended period of time. This research explored the use of lipid-protein nanoparticles, extracted from the spore coats of a few distinct spore-forming bacterial species, as a barrier coating to protect non-spore forming cells from external stressors. I aimed to understand how to prepare, characterize, and manipulate the highly resistant protective mechanisms provided to these bacteria for application across multiple families of beneficial bacteria. The ultimate goal is to increase survivability of probiotics in the presence of a range of distinct environmental stressors, both throughout manufacturing and digestion. Orally delivered probiotics must maintain a high, viable cell count and be able to be stored for long periods without nutritional influx to be effective in both humans and other animals.
My research contributes to the foundational work for the improvement of oral probiotic viability by exploitation of innate spore properties, namely by producing cross-species spore coated probiotics that have no sporulation mechanism themselves, and by showing the spore coat imparts its resiliencies on non-spore forming bacteria. In this work, I established the ability for mechanically extruded spore coat nanoparticles (SCN) to be used for single-cell bacterial encapsulation of distantly related probiotic species. This protective layer significantly decreases cell mortality under a wide range of physical stressors, including near boiling temperatures and acidic pH. I also analyze the ability for this coating and the cells’ biofilm to act as a filter for viral particles less than 150 nm in size. These characteristics are likely due to the spore coats’ function as a passive, filter-like material, but is reinforced by active spore coat proteins.