Difference between revisions of "Team:NCKU Tainan/Proof Of Concept"

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                          <p>    Menble is a special edible bubble that is a unique depression medication due to its form of coming with a very popular drink all around the world, bubble milk tea. Our depression medication is designed to be incorporated into everyone’s daily lives, in which everyone could easily access our bubble, which means that existing sufferers of depression, who can’t seek medical help due to stigma, can obtain this sweet, delicious drink with a bubble that contains our engineered bacteria to help cure depression by producing taurine.</p>
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                          <p>    The biggest challenge to Menble, our bubble, is the digestion of food in the stomach. Because most food coming from our mouth is digested in the stomach by the presence of a very strong acid called gastric acid, Menble must be ensured to withstand the conditions in our stomach, due to our product’s aim to release the bacteria in the intestine, where our bacteria is supposed to produce taurine and then transported to the brain via the gut-brain axis. Luckily, sodium alginate is able to withstand these extreme conditions in the stomach. Sodium alginate itself, has been proven to have very little effect on itself when under extreme stomach conditions[5]. Therefore, we believe that it is a perfect solution for our case, for it to encapsulate our bacteria and not release it until reaching the intestine, where combined action of acid and trypsin can break the structure of alginate down[5] and releasing the bacteria.</p>
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                          <p>    However, another challenge we encountered is that although alginate performs very well under acidic conditions, it does not, however, perform too well under basic conditions[6]. Therefore, we tested our bubbles containing E. coli Nissle 1917 to be submerged into phosphate buffers of four different pHs, reflecting the range of pHs of the milk tea drink. We also tested different bubble sizes to reflect the difficulty of swallowing among patients of mental illnesses[4], which themselves cannot chew our bubble to prevent early release of bacteria. Because of this, we are interested to make our bubble as small as possible, so that these people will not feel the bubble as they are being swallowed. As a result, we also conducted experiments using different sizes of bubbles to identify which bubble size has the most stable recovery rate that we can use for our final product. Below are the results of the rate of recovery of our bubble for the 14.14 mm3 (Large) bubble (Fig. 1.), 4.19 mm3 (Medium) bubble (Fig. 2.), and 1.77 mm3 (Small) bubble (Fig. 3.).</p>
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                          <p>    After confirming that most of the engineered bacteria can adhere to the walls of the intestine, we must prove that the bacteria can produce taurine. We designed our engineered bacteria to produce these enzymes only when the body is under high-stress levels, which are signaled by high levels of reactive oxygen species (ROS) and IFN-γ. The following experiments were performed to confirm that both oxidative stress and IFN-γ sensing systems can effectively detect their respective stress biomarkers and initiate taurine production. </p>  
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                                <p>    iGEM NCKU Tainan 2019 engineered <i>E. coli</i> Nissle and introduced an alternative pathway for tyrosine in the gut by adding <a href="https://2019.igem.org/Team:NCKU_Tainan/Design#TAL" target="_blank">Tyrosine Ammonia Lyase</a>. It converts tyrosine into a beneficial product, <i>p</i>-Coumaric acid. We improved the <i>p</i>-Coumaric acid production by <a href="http://parts.igem.org/Part:BBa_K2997009" target="_blank">changing the ribosome binding sites</a> from Native to B0034, the conversion of tyrosine into <i>p</i>-Coumaric acid increase by 1.73-fold.</p>
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                                <p>    We then further improved the conversion of tyrosine into <i>p</i>-Coumaric acid by adding a <a href="http://parts.igem.org/Part:BBa_K2997000" target="_blank">tyrosine transporter</a> (BBa_K2997000). As seen in Fig. 3, when BBa_K2997000 is added, the production of <i>p</i>-Coumaric acid is significantly higher than when BBa_K2998000 is not added. When tyrosine transporter is introduced into <i>E. coli</i> Nissle containing BBa_K2997009 and BBa_K2997010, conversion of tyrosine into <i>p</i>-Coumaric acid is increased by 1.44-fold and 1.31-fold respectively.</p>
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                                    <a href="https://static.igem.org/mediawiki/2019/d/d3/T--NCKU_Tainan--Results_tyrosine_to_pCA%2C_RBS_improve.png" target="_blank" style="width:90%"><img src="https://static.igem.org/mediawiki/2019/d/d3/T--NCKU_Tainan--Results_tyrosine_to_pCA%2C_RBS_improve.png" alt="" title="" style="width:100%"></a>
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                                    <figcaption>Fig. 3. <i>p</i>-Coumaric acid/OD<sub>600</sub> levels of <i>E. coli</i> Nissle with TAL and <i>tyrP</i> in LB + 1 mM tyrosine</figcaption>
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Revision as of 07:33, 17 October 2021



Bubble Production

Menble is a special edible bubble that is a unique depression medication due to its form of coming with a very popular drink all around the world, bubble milk tea. Our depression medication is designed to be incorporated into everyone’s daily lives, in which everyone could easily access our bubble, which means that existing sufferers of depression, who can’t seek medical help due to stigma, can obtain this sweet, delicious drink with a bubble that contains our engineered bacteria to help cure depression by producing taurine.

The biggest challenge to Menble, our bubble, is the digestion of food in the stomach. Because most food coming from our mouth is digested in the stomach by the presence of a very strong acid called gastric acid, Menble must be ensured to withstand the conditions in our stomach, due to our product’s aim to release the bacteria in the intestine, where our bacteria is supposed to produce taurine and then transported to the brain via the gut-brain axis. Luckily, sodium alginate is able to withstand these extreme conditions in the stomach. Sodium alginate itself, has been proven to have very little effect on itself when under extreme stomach conditions[5]. Therefore, we believe that it is a perfect solution for our case, for it to encapsulate our bacteria and not release it until reaching the intestine, where combined action of acid and trypsin can break the structure of alginate down[5] and releasing the bacteria.

However, another challenge we encountered is that although alginate performs very well under acidic conditions, it does not, however, perform too well under basic conditions[6]. Therefore, we tested our bubbles containing E. coli Nissle 1917 to be submerged into phosphate buffers of four different pHs, reflecting the range of pHs of the milk tea drink. We also tested different bubble sizes to reflect the difficulty of swallowing among patients of mental illnesses[4], which themselves cannot chew our bubble to prevent early release of bacteria. Because of this, we are interested to make our bubble as small as possible, so that these people will not feel the bubble as they are being swallowed. As a result, we also conducted experiments using different sizes of bubbles to identify which bubble size has the most stable recovery rate that we can use for our final product. Below are the results of the rate of recovery of our bubble for the 14.14 mm3 (Large) bubble (Fig. 1.), 4.19 mm3 (Medium) bubble (Fig. 2.), and 1.77 mm3 (Small) bubble (Fig. 3.).






Taurine Production Experiments

After confirming that most of the engineered bacteria can adhere to the walls of the intestine, we must prove that the bacteria can produce taurine. We designed our engineered bacteria to produce these enzymes only when the body is under high-stress levels, which are signaled by high levels of reactive oxygen species (ROS) and IFN-γ. The following experiments were performed to confirm that both oxidative stress and IFN-γ sensing systems can effectively detect their respective stress biomarkers and initiate taurine production.

Fig. 4. p-Coumaric acid/OD600 levels of E. coli Nissle with tyrP+ TAL w/34 in LB with different concentration of tyrosine



By culturing E. coli Nissle with dual plasmids containing TAL (BBa_K2997010) and tyrP (BBa_K2997009) in LB medium with different concentrations of tyrosine, we are able to prove that the TAL enzyme can specifically use tyrosine as its substrate. As seen in Fig. 4, although no significance in p-Couramic acid production in culture supplemented with 0.5 mM and 1.0 mM tyrosine, there was however an increasing trend. Furthermore, there was a significant increase when comparing culture supplemented with 1.0 mM and 2.0 mM tyrosine. We speculate that there was indeed a dose-dependent effect, but due to the limit of n-octanol extraction method was apparent.


Model

To ensure the biosafety of our engineered E. coli Nissle, we did a phenotype test by streaking out the can gene mutant bacteria on different plates and placing them in different conditions.

Fig. 5. Confirmation of can knockout in E. coli Nissle. E. coli Nissle and other strains were streaked onto agar plates and placed in (A) 0.04% CO2; (B) 5% CO2 conditions for phenotyping.

As seen in Fig. 5, Δcan::CmR and Δcan::FRT requires a higher CO2 level to survive. In doing so, we have proved that we have successfully knocked out the can gene.





Microfluidic Device

To ensure the biosafety of our engineered E. coli Nissle, we did a phenotype test by streaking out the can gene mutant bacteria on different plates and placing them in different conditions.

Fig. 5. Confirmation of can knockout in E. coli Nissle. E. coli Nissle and other strains were streaked onto agar plates and placed in (A) 0.04% CO2; (B) 5% CO2 conditions for phenotyping.

As seen in Fig. 5, Δcan::CmR and Δcan::FRT requires a higher CO2 level to survive. In doing so, we have proved that we have successfully knocked out the can gene.