Proof of Concept | SZPT-CHINA

Overview

Our goal is to develop a live bacterial skincare product with multiple efficacy. We are committed to providing users with the freshest glutathione and a brand-new skincare experience.

The forms of our products we envisioned are live bacterial emulsion/gel. We created a prototype of live bacterial emulsion/gel for proof of concept. The effect of formulation on the quality of BC film was explored to obtain the desired product. Moreover, we have successfully assembled GSH production module and lysis and safety module in E. coli TOP10.

Prototype

Bacterial gel

A prototype of live bacterial gel was created using wild type G. hansenii with Carbomer as the thickener. The influence of Carbomer concentration on the rate of bacterial gel film formation and on the mechanical strength and thickness of the resultant film was explored.

Higher Carbomer concentration (>0.2%) has a negative effect on BC film formation, leading to slower or even failure of BC film formation (Figure 1, 4, 5). We hypothesized that the higher viscosity affected the crosslinking between cellulose molecules synthesized by each bacterial cell. However, lower Carbomer concentration (≤0.2%) has a positive effect on the transparency, thickness and mechanical strength (Figure 1, 2, 3).

Compared with bacterial suspension without Carbomer, bacterial gel with 0.1% Carbomer concentration can form more transparent, thicker and stronger BC film, and the rate of film formation is little affected (Figure 2). Therefore, it is selected as our optimal bacterial gel.

Bacterial emulsion

A prototype of live bacterial emulsion was created using wild type G. hansenii with ethylhexyl palmitate as the oil phase, tween 80 as the emulsifier. The influence of emulsification on BC film formation was explored. We found that emulsification increased the opacity and thickness of the resultant BC film (Figure 6). And the effect of Carbomer concentration on the BC film formed by bacterial emulsion (Figure 7, 8, 9) is consistent with the effect of Carbomer concentration on the BC film formed by the bacterial suspension.

The bacterial emulsion with 0.1% Carbomer concentration is selected as the optimal prototype of bacterial emulsion as it is easy to apply onto the skin and has a relative high mechanical strength.

Assembly

We have successfully assembled GSH production module and lysis and safety module in E. coli TOP10.

Safety

To decrease the risks of environmental release of the engineered bacteria, we designed a kill switch which would respond to blue light. This would allow confinement of an engineered bacterium to an environment without blue light. (click Design & Results for more details)

References

[1] https://2021.igem.org/Team:SZPT-CHINA/Proof_Of_Concept
[2] https://2021.igem.org/Team:SZPT-CHINA/Experiments
[3] https://2021.igem.org/Team:SZPT-CHINA/Safety