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BACKGROUND
BACKGROUND
The prevalent epidemic of diabetes and high blood sugar in the United States because of the consumption of an excess of sugar is a serious health issue (Brody, 1999). One solution to this is instead, consuming artificial sweeteners. This study, which will examine the effects of artificial sweeteners, stevia specifically, will shed light on possible negative health effects surrounding the human microbiome that may prove that this ‘alternative’ may not be so healthy after all.
Artificial sweeteners are high-intensity sweeteners that give their consumers the experience of eating real sugar, but with little to no energy and or glycemic response; they provide the taste of sweetness without all of the calories.
Stevia, a lesser studied artificial sweetener, comes from a bushy shrub that falls under the sunflower family. It is also known as Stevia rebaudiana Bertoni. It is around 200 to 300 times sweeter than table sugar and contains eight glycosides. These are the sweet components that are isolated from stevia leaves in order to make the artificial sweeteners. These glycosides are stevioside, reabaudiosides A, C, D, E, and F, steviolbioside, and dulcoside A. However, the most abundant of these glycosides are stevioside and reaubauside A. Since stevia is a newer and more natural form of sweetener that is not approved by the United States Food and Drug Administration, there are fewer studies concerning the health aspects of stevia (Nichols, 2018).
PAST
PAST
My project is focused on artificial sweeteners and their effects on the human microbiome. Although there is much research proving the negative effects of artificial sweeteners altering bacteria in the microbiome, little is known about the effects of stevia. I plan on studying the effect of stevia glycosides, the sweet components that are isolated from stevia leaves, on Lactobacillus reuteri. Lactobacillus reuteri is a significant probiotic in the gastrointestinal tract. To do this, I used a phenol red fermentation test during my junior year science symposium project.
PRESENT
PRESENT
During my senior year, I worked on initial tests for for using C. elegans as a model organism for the microbiome. In the search to find an answer to my research question, the effects of stevia, I formed a methodology and plan of action for my tests with the help of my mentor, Dr. Berg. In this method, I looked at the gut microbiome bacteria isolated from the C. elegans, in order to have more controls, rather than directly through the worms. It was also more accessible for me in the MA lab. I first extracted bacteria from compost-enriched soil, then grew this bacteria culture independently in a soil slurry. Next, I added stevia in different concentrations, along with also having controls. The goal was to be able to compare the stevia against the controls to determine whether stevia was toxic through counting colonies and looking at their differences. However, I did got stuck and did not get clear results due to a lot of overgrowth in my plates. To fix this problem, I performed serial dilutions on a specific colony from one of my plates. The results from the serial dilutions are pictured on the the left. From this work, I was able to successfully isolate and culture this colony!
Future
Future
In the future, my experiments have laid the groundwork for a very exciting future project. Using C. elegans as a model organism, the next steps would be, to feed stevia directly to C. elegans and look at how it affects their microbiome. I hope that a future MARC student is able to pick up where I left off and continue this original research!
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