Chris S - What have you done?
Chris V - What we've done is to use
genetic engineering
to create a
strain
of bacteria that's able to respond to
light. The way that we do this is…If you look in a pond, a dirty pond, you'll see a green sludge. That sludge sometimes is bacteria, and the
reason
it's green is because it is able to do photosynthesis. And so it has to be able to see light. So, we took a
gene
from that bacteria that’s in that pond and we modified it so that it works in a bacteria that
normally is living in your gut, that doesn’t have to see light. (E. coli?) That’s right, E. coli. By bringing in this gene and doing a couple other modifications to the
genome
of E. coli, we made it so that individual E. coli cells are able to see light.
Chris S - When you
shine
a light on them, what does it do to the bacteria?
Chris V - It has a special
type
of protein, which is a molecule, much of the bacteria is made of protein, and this protein is on the surface of the bacterium. It's special in that it has a chemical that, when light is shined onto that chemical, then it changes the
shape
of the protein. This change in shape of the protein is recognized by the bacteria, and this
leads to turning
on a gene. And so in this way, you can
couple
shining light on the bacteria to the activation of a gene.
Chris S - And what sort of things have you made it activate? In your paper that you published this week, you actually made your bacteria change colour. What else could you do?
Chris V - You could imagine using this for a
wide range of applications. For example, in thinking about constructing
complex materials—it’s very hard to work with proteins, just from a
chemistry
perspective—and it would be
useful
if you were able to print proteins with a very high resolution. We are thinking about using this system in order to have
individual
bacteria turn on the production of proteins that maybe produce a particular
type of
material like
spider silk, or possibly do some sort of interesting
reaction.
Chris S - If you bought these bacteria as a digital camera in the shops, what number of megapixels would it say on the box?
Chris V - If it is able to turn on individual bacteria, it would be about
100
megapixels.
Chris S - So that's
incredibly
tiny resolution you can work at. You can make really, really fine structures.
Chris V – Exactly, so each bacteria is like a
pixel
on a
computer screen.
Kat - Are these bacteria dangerous at all?
Chris V - No, they're completely
harmless. What we're using is known as a
lab strain
of E. coli. This differs from
natural
strains in that almost
25% of its genome is
missing. Specifically, this strain of bacteria is
used frequently
in the lab because it's a very
safe
strain.
Kat – So it’s had all the bad stuff taken out of it.
Chris V – Everything’s been
removed, everything that’s sort of
unknown
or
bad
has been removed.