Team:Tokyo Tech/Project

1. Abstract

We designed educational tool for economics has three types of E. coli: Bank, Company, and Customer. (Fig. 2-1-1). Like the exchange of money and products in the real economy, we make these E. coli exchange products and money in this system. Company makes products, and sell them to customers. Customer pays money for the products made by Company. Here, signal molecule of the quorum sensing. 3OC12HSL and C4HSL represent products and money.

2. Interdependence between Company and Customer

We designed two genetically engineered E. coli, Company and Customer. Their circuits are shown in Fig. 2-1-2

Click here to see all image of animation

Since Company and Customer need each other to continue now-in-state economy, we designed the two E. coli mutually dependent. Company is dependent on money supplied by customer. Signaling molecule C4HSL represents money supplied. Customer is dependent on products supplied by Company. signaling molecule 3OC12HSL represents the Products from company. Detailed design of circuit is shown in the following sections.

2.1 Company

In the presence of C4HSL, which represents money, Company can produce chloramphenicol resistance gene (CmR) and LasI. CmR protects Company from chloramphenicol antibiotic action. LasI produces signaling molecules 3OC12HSL, representing Ｐroducts from Company.

We ascertained C4HSL dependent 3OC12HSL excretion in the experiment shown in Fig. 2-1-4. We measured the population of the cell in the presence of C4HSL. 具体説明欠けているThis result confirmed that the company cell produces 3OC12HSL in the presence of C4HSL.

If there are no C4 in the medium, Company cannot produce CmR even in the presence of chloramphenicol. This would lead to the death of Company, which represents Company’s bankruptcy.

We confirmed C4HSL dependent CmR production in the experiment(Fig. 2-1-6). We measured population of the cell in the presence of C4HSL. This result confirmed that Company cell produces CmR in the presence of C4HSL.

The basic design of circuit is the same to Company. In the presence of 3OC12HSL, which represent products, customer produces CmR and RhlI. CmR prevents customer from dying, and RhlI produces C4HSL, representing money. 3OC12HSL dependent C4HSL excretion was also confirmed in the experiment shown in Fig. 2-1-7.

If there are no products in economy, customer cannot produce CmR. This leads to the death of customer. This was also confirmed in the experiment shown in Fig. 2-1-8

Story1: Even though we succeeded co-culture assay experiment, the amount of E. coli we added to the culture was too much if we consider to expand our system to more number of pairs of “Company and Customer”, or more number of E. coli strains which can represent other roles in economy.（意味不明）

Story2: Despite of our careful assay, company and customer failed to grow in the assay.

3. Solution to the problem about
    Interdependence between Company and Customer

To make the system of customer and company grow even in the small culture, we proposed two solutions to the problem.

One of the solutions to the problem is improvement of Prhl in the Company.

3.1.1 Motivation

(Kato will add some contents here later)

There are just two ways to improve the growth of the Company and Customer system without changing the circuit.

We chose latter solution because modifying Prhl promoter is easier than improve LasI enzyme activity, because Max activity of Prhl promoter is lesser than other 良く使われる promoters.

3.1.2 Design of new Prhl promoters

As shown in Fig. , we added 3 new promoters, into the parts registry, derived from Prhl. First we made Prhl_RR. Prhl_RR was designed by 「論文の人」.  Taking Plux, we changed lux boxes of Plux to Prhl’s. The assay result is shown in Fig. 2-1-11.Although the maximum expression rate of Prhl promoter improved, leakage of the expression also increased.

High level of leakage is not suitable for the company and customer system because mutual dependency will be broken. Therefore, we the designed new promoters named Prhl_LR and Prhl_RL in Fig.2-1-12. We can see Prhl_RL shows high maximum expression rate and low leakage

3.1.3 Co-culture

(don’t know whether the experiment is planned or not. I can insert the simulation result, but experimental result would be more persuasive)

3.2.1 Motivation

In the real economy, a central bank will supply money to the economy if there is not enough money. So we designed Bank E. coli that supply money to the economy. Bank E. coli help interdependence between Company and Customer.

3.2.2 Design of Bank E. coli

Circuit design of Bank E. coli is shown in Fig. 2-1-13. Bank E. coli regulate the money supply in the economy.

When the money supply in the economy becomes lower than certain level, Bank supply money by expressing RhlI. On the other hand, when money supply becomes higher, Bank E. coli will collect money from the market by expressing AiiA. We will walk through the whole mechanism below.

Click here to see all image of Animation

Step1: Collection state

If there are excess amount of money in the economy, Bank is in the collection state. In collection state, Bank expresses AiiA. AiiA decompose C4HSL and 3OC12HSL. Thus reducing money supply in the economy.

Step2: Change to distribution state

Once the amount of money supply decrease, Prhl/lac followed by AiiA and TetR will lower the expression. Instead, Ptet activates to express RhlI and LacI.

Step3: Distribution state

When the bank is in the distribution state, Bank expresses RhlI to produce C4HSL, money to the economy.

Step4: Change to collection state

If Bank is always in the distribution state, Bank will supply too much money to the economy. Thus when the amount of C4HSL is excessed which will activate the Prhl/lac to express AiiA. When Bank finished this change, bank will switch to the collection state.

3.2.3 Modeling results

C4によって、単安定、双安定、単安定と切り替わる相図(加藤君よろしくお願いします。) Since we couldn’t construct Bank, we have simulated the Bank system with Company and Customer. When we add bank to the Company and Customer, the simulation predicts the culture grows well. In this simulation, Bank switches state from distribution state to collection state as shown in Fig. 2-1-20.

4. Economic Wave

According to the advice we received during the presentation practices企業人への, we began to consider economic waves. In the real economy, there are long- term financial wave named Kitchin inventory , Kondratiev wave etc. These long- term financial wave deeply affect the whole economy. We were suggested that ignoring these waves can be a crucial defect in the system. Therefore, we integrated this wave into our system.

When only Customer and Company are present…. (still not completed because of the lack of simulation results) ここに波をシミュレートしたときの原稿を入れる

5. Reference