Lemon Shaping

Countdown

This page is under Terry's responsibility

• Deadline: 08/oct.
  • Text
• Deadline: 12/oct
  • Final review by Solenne.

Introduction

We decided to build up a lemon tree becsause it is traditionally admited that tree embodies development, evolution and life. This image send back to one of the first problematics evocated in our project : define life. Tree also alows us to figure out « time flies » and its impact on living things, seasons fter seasons. In the case of lemon tree, evenif leaf are evergreen, we can easily observe formation of buds, flowers and finaly fruits. This thematic of time’s impact on living organisms has been exploited in our wiki with the branch which figures on top of the page : this branch grows up as long as we progress in the wiki. The work we have done to make the lemon pass from green to yellow as well as the expression of perfumed molecules enable to mime faithfully living things … this returns to the following questions : - is synthetic biology blurring the frontier between living organisms and inert matter ?

We wanted to create our lemon on a base of agar gel, which can be a good medium for bacteria and enough cohesive to support its own structure. Our very first idea was to print the lemon with agar, but 3D printer are still pricey and the realisation quite difficult given that we do not have much time allowed. We eventually opted for a more conventionnal way to achieve our objective : molding !

Realisation

First of all, we needed to know the optimal concentrations of agar to make our gel. Too much agar, and the bacteria colors would be masked by the natural one of agar, plus, air would not properly pass through and bacteria would die. Not enough agar, and the structure would collapse. Various tests have been carried out and we conjectured that the most efficient gel for our purpose has a concentration of 25 mg/l.

Secondly, We tried different concentrations of bacteria to see if our gel let appear the color of our bacteria. The problem was the LB medium since it is naturally colored. We eventually opted for a colorless one : M63 medium. We also prepared bacteria expriming amplified Fluorescent Protein in the case that we could not achieve our chromoprotein.

Concerning the mold itself, we came up with an alternative solution to mold using only agar but we finally had two other options : a home-made mold of silicon and an other mold made by the Lyon team using a 3D printer.