We live in biological world completely surrounded by rich communities of microorganisms, but often in a cultural world that emphasizes total antisepsis. But "sanitized and pasteurised for your protection" is the antiseptic symbol of sensory death. Because not all smells and bacteria can be pleasant, the consequences of hyper-sanitation could be that we decide to have none at all. Smells, bacteria, and bacteria that produce smells surround us all the time; chemical detection is an ancient biological communication tool used by bacteria and animals alike. Smells and bacteria are a crucial component in defining, understanding of and
orienting in any environment.

The intersection of our interests in smell and microbial communities led us to focus on cheese as a “model organism.” Many of the stinkiest cheeses are hosts to species of bacteria closely related to the bacteria responsible for the characteristic smells of human armpits or feet. Can knowledge and tolerance of bacterial cultures in our food improve tolerance of the bacteria on our bodies or in other parts of our life? How do human cultures cultivate and value bacterial cultures on cheeses and fermented foods? How will
synthetic biology change with a better understanding of how species of bacteria work together in nature as opposed to the pure cultures of the lab?

Will we be able to re-engineer bacterial communities as readily as we can add or delete genes to and from E. coli? How will synthetic biology change our relationship to the microbial communities that surround us?

Sissel Tolaas was a speaker at the World Science Festival in New York in June, discussing her Synthetic Aesthetics collaboration with Christina Agapakis. Sissel says, "Smell is one of those senses where context can play a huge role. A fine cheese and a dirty foot share the same molecular smells, yet one is a delicacy and other is repulsive."

For their BO_BAD_CHE project, Christina and Sissel collected bacteria from people and used it to make 'human' cheese. "We decided to focus on cheese as a metaphor for the human organism", explains Sissel. These personalised dairy products challenge the old adage of "we are what we eat", and the boundary between what we make and who we are. Their collaboration continues: most recently, at the SB5.0 conference at Stanford in June they ran a live cheese-making session, building a library of cheeses made from bacterial cultures swabbed from the global synthetic biology community. 

Synthetic Aesthetics' resident and Harvard synthetic biologist Christina Agapakis in conversation with Maggie Koerth-Baker, discussing synthetic biology, design, cheese and women in science and blogging. Watch the discussion here!

By Anton Plotkina,1, Lee Selaa,1, Aharon Weissbroda, Roni Kahanaa, Lior Haviva,
Yaara Yeshuruna, Nachum Sorokerb,c, and Noam Sobela,2

Department of Neurobiology, The Weizmann Institute of Science, Rehovot 76100,
Israel; Loewenstein Rehabilitation Hospital, Raanana 43100, Israel; and
cThe Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978,
Israel; Edited* by Brian A. Wandell, Stanford University, Stanford, CA, and approved
June 24, 2010 (received for review May 13, 2010)

A.P. and L.S. contributed equally to this work.
Link

 A lot of synthetic biology is about getting biology to be more like electrical engineering, designing genetic "logic gates" to create a living circuit board. Beyond analogies, however, cells have many fascinating electrical properties--proteins that transfer electrons like wires, membranes that separate ions and create an electrical charge that drives the metabolism of the cell, channels through these membranes that open and close to activate an electro-biological response. Electrons are electrons whether they are in proteins or copper wires, and many scientists have designed ways to connect the soft and squishy electrical flows of living systems to the hard electricity of computers, creating hybrid cyborgs that play to the different but compatible strengths of cells and computers. One emergent application of such technology is in the design of chemical sensors, connecting the amazing ability of cells to sense and respond to very small changes in the environment to a human-readable output on a computer screen or even to a robot that can move and seek out the source of a chemical.

An amazing recent paper from a Japanese research group shows how such a cyborg nose could work. The team worked with frog eggs, large and hardy cells that are relatively easy to manipulate one at a time, placing them into a specially designed chamber where the electrical state of the cell could be measured by a computer while different solutions flowed across the surface of the cell. However, egg cells can't "smell" on their own, they need to be engineered with receptors that can sense and respond to chemicals in the solution. To accomplish this, the researchers engineered the egg cells to express the smell receptors from various insects on their surface. Mammalian smell receptors activate a cascade of signals inside the cell that are difficult to measure without biochemistry, but insect smell receptors are much simpler, opening a channel through the membrane that rapidly changes the electrical state of the cell. Since the electrical potential is constantly being measured by the special chamber, when the right chemical binds to the receptor and opens the channel, the computer "sees" the smell. 

Once the computer sees the chemicals, that signal can be translated into any other mechanical system. In a simple but awesome demonstration of the ability to connect the chemical biosensor to robots, the egg cell chamber was mounted into the nose of a robotic mannequin head. When the chemical was sensed, the robot shook its head from side to side. The cells are highly sensitive, able to sense very small chemical concentrations, and highly specific, able to distinguish between similar molecules with a high tolerance for noise.

Cells don't have to be computers to be able to do amazing things with computers. Biology has unique and powerful skills, and biologically inspired and biologically integrated engineering has great potential for all kinds of new cyborgs.