Chiba/Project Design

From 2007.igem.org

Project Design

Concept

(photo taken from Agriculture, Forestry and Fishes Technical Information Society, Japan, http://www.afftis.or.jp/index.html)
We aimed to make a spherical gathering of bacteria such like marimo by ordering bacteria go get together and stick to each other.

What our system requires

1.Sticky Tag Make a His-tagged Flagella. We aimed to stick bacteria by displaying histidines (which bonds each other through metal ions) on the flagellar filament. 鞭毛にヒスタグをディスプレイし，金属イオンを介して，バクテリアを接着することを目指した． Fig1. His-tagged flagella as a bactria linker. This image depicts only one tail as flagella (the real bacteria have about ten flagella per cell).

2.Communication Make a Bacterial Communication. We make 2 types of cell(sender&receiver) having different gene circuit. Senders sticking each other in advance send a signal to receivers and receivers grow sticky hands. 違う遺伝子回路を持つ２つの細胞（sender&receiver）に分ける．あらかじめお互い結合しているSenderが，周りのreceiverにシグナルを与えてsticky handsを生やす．そして合体． Fig2. Bacterial Communication.

3.Size Control Make an AHL localized region for quorum sensing. Fig3. AHL concentration gradient.

How Our System Works

1. Senders whose flagella display the histidine tags stick to each other through metal ions. This becomes the core of Bacteria Marimo. The senders also produce AHL to sign the receiver cells.
   
2. Receivers express his/flagella and GFP in high [AHL]; only when they get close to the senders core.
   
3. Receivers stick to the senders core and themselves through metal ions.... one after another.
   
4. As seen, the cluster grows like a snowball. At the same time, the receivers degrade AHL and thus AHL diffusion space around the mixed cluster limited. By controlling the rate of AHL degradation and so on, one can define the size of such Bacteria Marimo.