Tooth decay is a global health issue, which happens very often in the lifetime of a human being. Think about the children not brushing their teeth properly before going to bed. It’s very terrible and hard time to being parents. Our initial proposed end users were children around the globe, especially who don’t have habits to brush their own teeth. After taking a survey on different ages, we decided to expand our target from children to adults. Now, our proposed end users are people all around the world. And we’re in charge of taking care everyone’s teeth.
ENVISION
We expect our product to be convenient and simple to use. Making our product into lozenges with oral probiotics is the perfect choice for us. We hope our users to put one tablet of our lozenges in their mouth before going to bed every day. And image the probiotics live in the oral environment and antagonize against etiological pathogen such as S. mutans. If possible, brushing their teeth before consuming our product could increase the effectiveness.
IMPLEMENT
We developed a homemade candy, named Cleandy, meaning a candy that can clean your teeth. It is composed of sugar alcohols and our engineered probiotic (i.e., E. coli probiotic strain, Nissle) with capable of producing bactericidal agents. We focused on natural substance to defend the caries-associated bacteria like S. mutans. We researched the antagonistic relationship between S. mutans and S. sanguinis and found H2O2 effect on the growth inhibition of S. mutans. Then, we designed the Cleandy with probiotics producing H2O2. With Cleandy, children and adults can both maintain good oral health.
SAFETY
Chassis
E. coli Nissle (EcN) is a nonpathogenic bacterium isolated by Alfred Nissle in 1917. Since then, many researches used and engineered the strain as a probiotic or therapeutic agent. Dr. Divya Pandya also mentioned in a review paper entitled “Benefits of Probiotics in Oral cavity “ and pointed out E. coli Nissle species is potential used as probiotics in oral cavity with a non-lactic acid producing feature.
Parts
The device we created contains pyruvate oxidase (SpxB), aquaporin (AQP) and catalase (KatG) to produce H2O2, facilitate the transport and detoxify the oxidative stress. All of the three parts are normally and widely present in bacterial and mammalian cells and also in the oral environment. Therefore, we believed they are very safe and have no concerns about any risk to human or the environment.
Application
Image the application in the real world, the candy we made contains E. coli Nissle cells, which will be released when dissolved in the mouse. Prior to reaching to the intestine and be absorbed by tissues, they have to pass through the stomach and incubate at the acidic environment at pH of 1.5 - 3.5 for 4 – 6 hours. Then, we tested the growth of Nissle strains in the medium at pH of 2 compared to pH of 7. The results in Fig. 1 indicated that the bacterial growth was dramatically inhibited and no bacteria survived on agar plates after 5-min treatment in media at pH of 2, suggesting a safe usage of the candy with probiotics in the real world.
Fig. 1. The growth inhibition and survival rate of E. coli Nissle in LB medium and on agar plate at pH of 2. (A) The values of overnight culture were measured at OD600. The percentage of growth inhibition was calculated by dividing OD600 at pH = 7. (B) 104 bacterial cells were treated in LB broth at pH of 2 for the indicated time, followed by spreading onto the agar plate. The survival rates were ~10%, 0%, 0% for 1 min, 5 min, 30 min, respectively.
CHALLENGE
The engineered probiotic (GM E. coli probiotic strain, Nissle) in our prototype, Cleandy, isn’t natural to our oral environment. We hope to make our probiotic a genetically modified oral species (Streptococcus mutans) in the future to maintain the ecological balance of the oral environment.
