What we are doing is to use photosynthetic bacteria
that are just running off sunlight and carbon dioxide.
They're using the energy from the sun,
they're using the carbon dioxide from the air,
and then they're producing useful molecules, commercially important molecules.
In this case, the molecules are sugars and also lactic acid.
Sugars are obviously important,
that are the major food substance.
Something like $60 billion worth of sugar is sold every year,
and lactic acid which is the other molecule that we talk about in this paper is
important for biodegradable plastics.
Those two molecules are a good representatives of what you could make by this approach.
There are a couple of things that were unique about this work.
One thing is the production of sugar by metabolic engineering.
Sugar is probably the most important carbon-based compound after fuels in the world,
and it has never really been produced by genetic engineering.
Right now it's just produced by sugar cane,
and sugar beets, and so forth.
So, we think we are probably the first person to start to move
towards a practical method of producing sugar by metabolic engineering.
One unique aspect about the science in this paper is that we had to not only
engineer the enzymes that produce these molecules into the photosynthetic bacteria,
but we also had to introduce transporters that would allow the molecules to be secreted.
Photosynthetic bacteria are designed by nature to be extremely self-sufficient.
They absorb carbon dioxide,
they absorb minerals, and they absorb sunlight,
and that's really it.
They don't have the elaborate transport systems that most organisms have,
because they're not really feeding off the world,
they're just taking up minerals.
Other organisms will take up sugars,
they will secrete waste products,
photosynthetic bacteria really don't do that.
So, we engineered these bacteria to have enzymes
plus transporters to allow the secretion of the products that they were making.
In terms of sustainability,
there's also the clear advantage in that we would not have to transport these molecules
across the world in order to get them
into the United States or to get them into countries that can't make them.
That would have a huge impact on local self-sufficiency
and also simply reducing the amount of fossil fuel that is burned in transportation.
Another important aspect of the work is that,
instead of using energy-intensive processes to make these molecules
that is going to lead to carbon dioxide production and release into the atmosphere,
what we're actually doing is capturing carbon dioxide out of
the atmosphere and it's going into these carbon-based molecules.
That means we would have a carbon neutral or even a carbon favorable
process whereby we're capturing CO2 that may be from a coal-burning power plant,
for example, and then turning it
into something useful instead of having it be essentially a pollutant.
