Our aims
The primary goal we wish to achieve through hardware is to create an interface between genetically engineered bacteria and the physical & social issues we care about – body odor. In hopes of bringing synthetic biology into people’s daily lives and improving them, our hardware will serve as “home appliances” rather than industrial reactors. Furthermore, we hope our designs will inspire future teams who are interested in skin treatment and multi-media culturing.
Summary
We designed a small-size bioreactor that provides a constant supply of a fengycin solution, which can be applied to the human body through a spray bottle or a water-absorbing patch.
Considering how much people's opinions and acceptance of bacterial products vary, we designed our products to be variable between bacteria and no bacteria conditions and with scent and no scent versions to suit the customers’ preferences.
Description
Domestic Deodorant Fermenter is a two-media bioreactor that allows the genetically engineered Bacillus subtilis to be culture first in ordinary culture media and then with expression media (isotonic solution containing electrolyte and inducers) which will induce the production of fengycin in B. subtilis. One important function of this product is to produce a fengycin-containing solution without living bacteria and culture media which could accelerate the growth of unwanted bacterial species in the axillar. To this end, the bacteria are confined in envelopes made of filter paper resembling the form of “tea bags”. Because of our special bridge-like design, the culture media in the “tea bags” will be squeezed out when the sliding rail on the top of the lid moves and pulls the “tea bags” through the narrow area in the middle. The trace amounts of culture media remaining in the envelopes would be diluted by the bulk of expression media. (may need some evidence to prove this) Also, the two media are supplied by external containers to allow exchanging and refilling, and magnetic stirrers will ensure the rate of substance and exchange during culture.
The workflow of using this hardware would be first culturing the bacteria on one side of the tank containing culture media and transferring it to the other side which contains the expression media. After a period of time, the expression media will be drained out from a tube near the bottom and becomes our final product. Then by resetting the position of the “tea bags” and refilling expression media, the product will be ready for a new period of functioning.
Implementations
To practicalize our hardware, we developed two ways to apply the deodorant produced by the bioreactor to human bodies. First, the solution produced by the bioreactor can be directly applied to the skin through a spray bottle and function as a deodorant as it contains the antibacterial molecule, fenygcin. In addition, a patch that absorbs the fengycin solution can suppress the growth of odor-causing bacteria in the axilla.
Future development
To fully exploit B. subtilis’ antibacterial capacity, we plan to develop a hydrogel-based patch based on a study by Tzu-Chieh Tang et al. in which they developed a hydrogel-based system to effectively confine bacteria while allowing the transferring of medication or other molecules.
Reference
Chen, Q. W., Qiao, J. Y., Liu, X. H., Zhang, C., & Zhang, X. Z. (2021). Customized materials-assisted microorganisms in tumor therapeutics. Chemical Society Reviews.