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 with metal ions) on the flagellar fillament. 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. 鞭毛は便宜上１本しか描いてないが実際は1~10本/細胞．

2.Communication Make a Bacterial Communication. We make 2 types of cell 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 concentration gradient for quorum sensing. Fig3. AHL concentration gradient.

How Our System Works

1. Senders stick to each other by way of metal ions using flagella displaying histidine tags. This becomes the core of Marimo. They also produce AHL to call 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 core (the clustered senders) by way of metal ions.... one after another.
   
4. This way, cluster and grow like a snowball. At the same time, receivers degrade AHL and thus limit the space where AHL reaches. By controlling the rate of AHL degradation, one can define the size of bacterial culster, MARIMO.