Banana bacteria is an olfactory exhibit using living bacteria that produce a banana-like odour rather than the foul smell normally associated with bacteria.
Banana Bacteria (2011),Techfest 2012, IIT Bombay, Mumbai, India, January 2012 These bacteria have been genetically altered by removing a gene responsible for the foul smell commonly found in bacteria and adding a genetic design that enable bacteria to synthetically produce banana oil. Finally, we grow the bacteria in a special odourless media.
The work combines several techniques and constructs, in particular it uses a genetic design developed by a team at MIT (iGEM 2006) for the synthetically production of banana oil.
Banana Bacteria (2011) plate of indole inefficent E.coli strain transformed with plasmid.
C-LAB explores how new metabolic possibilities emerges through synthetic biology. Scientifically, it illustrates how synthetic biology can make an impact on the flavouring industry.
Banana Bacteria (2011), plates containing library of genetic parts (iGEM 2010).
Artistically, it provides us with awareness that both confuses and challenges our senses; the foul warning smell of bacteria is exchanged with the sweet smell of banana. The display allures to future scenarios where synthetic odour could be produced by bacteria inhabiting humans, such as replacing bad breath with a minty fresh breath.
The work began after receiving the library of standardised parts from the MIT partsregistry. The process of putting plasmids containing the genetic parts into cells (transformation) is relatively straightforward. Using antibiotic selection, colonies were picked and grown in liquid culture. Cultures were up-scaled to grow in 200ml bottles, and once turbid or dense, these were placed on ice and a small amount of isoamyl alcohol was added allowing the conversion process to commence.
The experience of banana smell was at first a bit confusing. The isoamyl alcohol seem to have a faint banana scent in its otherwise pugnant alcohol smell. As time progressed the banana smell became sweeter and less alcohol like. Normal strains of E.coli (such as XL-1 BLUE) have their natural smell that blend in with the banana smell producing a mixture between sweet and rotten, or a bit like rotten banana. When sharing the flask with colleagues the result was mixed, some said ‘it just smells like E.coli’, others where unclear and but several thought, like myself, thought it smelt like banana. Through a contact at London School of Economics, I was able to obtain a special strain (YYC912) without the natural smell of E.coli. The strain has a genetic knockout that removes its natural smell. The strain was received from the University of Lusanne (Switzerland).
Another factor was the LB-broth, which has a sweet caramel-like scent. To overcome this a scentless growth media was made by making a special media called M9 consisting of several components (e.g. salt solutions, amino-acids and vitamin solutions).
The lab work explored variety of ways to experience bacteria smell. Materials and protocols were setup that would allow this work to be reproduced and shared with audience.