We propose a novel solution to address the social embarrassment caused by stink fart and body odor of patients who undergo enterostomy: engineering probiotics to improve the acrid intestinal smell. We construct three different metabolic pathways in E.coli to convert ammonia to arginine, hydrogen sulfide to cysteine, and produce myrcene respectively. The experimental results are approximately consistent with the expectation. Compared with the wild-type, our engineered E.coli consumes 40.47% more ammonia, converts and produces 98.72% more cysteine, and produces 0.034185 mg/ml myrcene. We improve a more efficient feedback-resistant SAT better than that of the previous research (Kai, 2006). After further refinement on the genetic pathways and rigorous biosafety tests, our research can be developed into an actual product such as a capsule that can be orally delivered into the intestine, where the probiotics function. Then, people can quietly break wind in public space without bothering about the acrid smell, and patients who undergo enterostomy can no longer worry about their body odor in social situations.
We used sodium potassium tartrate tetrahydrate reagent to participate in the reaction， reflecting ammonia content by detecting the concentration of NH4+ in solution. The concentration of cysteine was measured with the acid ninhydrin reagent. And the production of myrcene was quantitatively detected by a gas chromatograph. Our methods of detecting the products are scientific, simple and accurate. They’re based on the literature and therefore credible. The dosage of the tested drugs is very clear. As the experimental equipment and experimental operation are carefully recorded, it is highly feasible and conducive to the iGEM team's reference in the subsequent research on relevant aspects.
Part: Based on Part:BBa_K731000, we obtained cysE-Wildtype Part:BBa_K3595004 only containing the cysE coding sequence from E.coli dh5a genome. In order to increase cysteine production, we constructed different cyse mutant genes Part:BBa_K3595005,Part:BBa_K3595006,Part:BBa_K3595007, Part:BBa_K3595008,Part:BBa_K3595009, Part:BBa_K3595010, Part:BBa_K3595011. By placing these elements downstream of the PTac promoter, we successfully constructed pBR322-KanR-pTac-cysE and pBR322-KanR-pTac-cysE-mutant.In addition, we established a method for quantitative detection of cysteine, and have completed the functional test of wild-type cysE and different cysE-mutants;
We created the following biological part to assist future research on synthetic biology:
BBa_K3595001 BBa_K3595002 BBa_K3595003 BBa_K3595004 BBa_K3595005 BBa_K3595006 BBa_K3595007 BBa_K3595008 BBa_K3595009 BBa_K3595010 BBa_K3595011 BBa_K3595012 BBa_K3595013 BBa_K3595014 BBa_K3595015 BBa_K3595016 BBa_K3595017
Kai Y, et al. Engineering of Escherichia coli L-serine O-acetyltransferase on the basis of crystal structure: desensitization to feedback inhibition by L-cysteine. Protein Eng Des Sel 2006;19(4):163-7.