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Team:UIUC Illinois/Project/PuppyProbiotic
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Revision as of 02:36, 18 October 2014
Puppy Probiotics.
"The art of research [is] the art of making difficult problems soluble by devising means of getting at them. "
An Introduction
Theobromine is a 3,7- dimethylxanthine which has a bitter taste and is naturally present in many substances as well as a metabolite of many chemical cascades. Theo being the greek root for “god” and broma meaning “food” combined form Theobroma, the genus of the cacao tree which is used in chocolate formation. Despite its abundant and delicious presence in chocolates and tea leaves, Theobromine poses a great risk to animals who are not made to digest it. Dogs who are exposed to chocolate and subsequently theobromine exhibit high blood pressure, can begin to seize and as many veterinary clinics have reported, result in death. To combat this issue, the UIUC iGEM team is focused on creating a probiotic that when administered, can combat the ill effects of theobromine on livestock and domesticated animals. We explore the potential benefits of the ever increasing manufacture of probiotics as well as colonization of digestive tracks to supress negative chemical effects. In our venture to degrade theobromine, we utilized cascades that broke down not only theobromine, but its precursor caffeine. Caffeine and theobromine are both nervous stimulants and vasodilators which can be beneficial or malignant depending on context. Examining the scope of coffee production, we discovered that despite being a rich source of nitrogen and carbon, coffee waste is not as widely used as biomass for fertilizers due to its caffeine content. We aimed to provide a way to remediate coffee waste to make it a viable feed source.
Imagine...
Imagine drinking a cup of coffee. You stolidly sip your espresso and soon enough you feel a warm sensation cajole your body into getting that assignment done. However, you notice you're fidgeting uncontrollably, the room starts spinning and you begin to vomit. Ambulances, the noises are familiar, you've just seized. You're a dog.
What just happened?
Canines and many small animals are incapable of metabolizing theobromine and related stimulants as fast as humans can. Chocolate contains theobromine, an alkaloid that has stimulant properties. An excess of the stimulant builds up and begins to overstimulate the animal, thus leading to many malicious side effects. Ranging from slight nausea to death, consumption of these compounds are harmful for the animal. Chocolate can affect the animal regardless of the amount administered. Even the smallest amounts can produce side affects like diarrhea. In fact, theobromine has been employed to ward off pests of the same genus as canines: "Results indicate that mixtures of theobromine and caffeine have the potential to be developed into a selective, effective, and socially acceptable toxicant for the control of pest coyotes."[1] Caffeine in humans is degraded via a cascade mediated by Cytochrome P450. This is the primary molecule that allows for xanthine demethylation. In canines and smaller species, the cytochromes are available, however altered in a way that prevents caffeine degradation! Despite sequence homology to Human's P450, a canine's metabolism does not function similarly!
What can we do?
Problem solving
In effort to solve this problem, our team looked at the biological cascade of caffeine and theobromine. Since our goal was to degrade caffeine into something less harmful, we looked to digestion. We uncovered that theobromine can in fact be degraded into subtituents that are less harmful, namely a cascade that converts it to uric acid, a molecule that the dogs could excrete as waste
Nature's answer
We discovered that the organism Pseudomonas putida CBB5 endogenously metabolized caffeine and subsequent methylxanthines. In fact, the organism degraded the compounds using the proteins NdmA (N-Demethylase A) and NdmB, both of which are Rieske nonheme iron monooxygenases, NdmC, another demethylase and NdmD, a reductase. By using this pathway, the organism is able to use caffeine as a carbon and nitrogen source.[2] Too good to be true? No. In fact, a previous iGEM team, UT Austin 2012 Caffeinated Coli, harnessed the power of this novel pathway in their own project! We were ecstatic to learn that the pathway was available in biobrick form and ready for us to manipulate.
UT Austin developed this part by rearranging the operon of CBB5 and developed this part:
By using this construct, we were eager to repurpose it to degrade theobromine. Degrading theobromine meant targeting the host where theobromine failed to be degraded. An enteric approach is what we chose, thus leading us to design a probiotic. We chose Latobacillus, specifically Lactobacillus Plantarum WCFS1 as our fermenter of choice. Our plan was to PCR out the genes corresponding to theobromine degradation (NdmB, NdmC, NdmD) and assemble that into a shuttle vector for Lactobacillus.
Plantarum to propagate the Puppy Probiotic
How could we deliver our theobromine degrading enzymes to the gut of the host? We decided upon the ever increasingly popular probiotic. Probiotics are foods or supplements that harness microbes to produce products for a positive purpose. To create a probiotic, delivery of an organism was necessary. Lactobacillus Plantarum WCFS1 is a strain of Lactobacillus that is capable of surviving gut conditions as well as thriving in the endogenous microbiota of the organism it's in. By having Plantarum in the gut, we hoped that it would produce enzymes that could survive and propagate in the gut itself. Plantarum became the organism we decided to transform our products into.
illinoisigem@gmail.com 
