Description

The indigenous gut microbiota in humans possesses the ability to synthesize neurotransmitters that are hypothesized to modulate behavioral, cognitive, and emotional processes of the body via the gut-brain axis. Since the emergence of this axis theory, researchers have been interested in genetically modifying probiotics for use as edible delivery vehicles of neurotransmitters to treat a variety of illnesses. There is limited experimental evidence regarding the effectiveness of these probiotics in the gut as this is a relatively novel concept.

Thus, our project is aimed aimed at engineering an effective probiotic capable of producing higher levels of gamma-aminobutyric acid (GABA) to treat patients with anxiety and certain bowel disorders. The effectiveness of this probiotic in the human gut will be tested and refined using the gut of Apis mellifera , honey bee, as a model. Like humans, bees have a dynamic gut microbiome that influences host physiology. GABA is the neurotransmitter of interest due to its proposed anxiolytic and digestion-regulating effects. Furthermore, the behavioral effects of GABA in bees have been well-documented. We can therefore expect to observe certain behaviors from bees after they ingest the GABA-producing probiotic, ultimately allowing us to gauge its efficacy.

In order to create an accurate and translational model, we will utilize Lactobacillus plantarum as our probiotic, as it is native to the guts of both humans and bees. L. plantarum is also commonly found in a wide variety of foods, including yogurt, kimchi, and cheese, allowing us to easily utilize our genetically-modified version to create medicinal food. Although L. plantarum can naturally synthesize GABA, we intend to expand the GABA-producing potential of the bacteria by characterizing and subsequently optimizing the expression of glutamate decarboxylase, an enzyme responsible for converting glutamate into GABA. Dosage of GABA will be limited through the incorporation of the agr quorum sensing system from Staphylococcus aureus. The success of this project will invariably allow for other synthetic biologists to use the bee gut as a testable paradigm for designing effective probiotics.