Cyborg bacteria outperform plants when turning sunlight into useful compounds

https://phys.org/news/2017-08-cyborg-bacteria-outperform-sunlight-compounds.html

by dnetesn • 9 years ago

127 42 9 years ago

emeijer• 9 years ago

"The bacteria operate at an efficiency of more than 80 percent"

Really? If this technology is able to convert energy from sunlight + co2 into carbon based fuels at 80% efficiency, that's quite astounding. Something like that could solve the whole energy storage problem we have with solar and wind energy. Almost sounds too good to be true.

digi_owl2• 9 years ago

The elephant, as always, is "will it scale?"...

agumonkey• 9 years ago

btw, is there a mindset about centralization efficiency (as in large scale manufacturing) vs small scall distributed ?

If everybody bred these as they see fit, the scale issues might not appear. But I'm surely missing something.

tomjen3• 9 years ago

It is bacteria. Those usually have no issue scaling.

visarga• 9 years ago

Elephants don't scale up. Sorry about that.

sp3322• 9 years ago

I think it's referring to how efficiently it uses the energy after it is collected by the solar panel. So the collection itself might be <20% efficient, but the synthesis of new materials can be very efficient after that.

bluGill2• 9 years ago

There is more than enough sun falling on the ground in deserts to supply all the energy humans use at ridiculously small conversion efficiencies. It doesn't do us any good because we don't know how to capture that.

SCHiM• 9 years ago

No the problem there is actually transporting that. It's no use to build a solar farm there and then stretch a long copper powerline back to wherever it is needed because of the losses involved.

woliveirajr• 9 years ago

Upon addition of a simple Cd2+ salt and the sulfur amino acid cysteine, the non-photosynthetic Moorella thermoacetica self-photosensitizes through the synthesis of light absorbing CdS nanoparticles. This hybrid organism, M. thermoacetica-CdS, produces acetic acid from CO2, water, and light at quantum efficiencies above 80%.

One problem is that cadmium is toxic, highly toxic, so the removal of it before refining any fuel will have to follow strict rules.

And wikipedia will have to be updated :)

Although cadmium has no known biological function in higher organisms (...)

(https://en.wikipedia.org/wiki/Cadmium)

jacobush• 9 years ago

Higher organisms.

itchyjunk• 9 years ago

When I see tech like this, I think of how this will help us colonize space faster. But I wonder if there is a good scifi plot twist to be had when stuff escapes the lab (here or in space). AKA, when is it appropriate to add the weight of safety to research and experiments?

Retric• 9 years ago

There is not really much Cadnium in the wild. Humans are made from Oxygen (65%), Carbon (18.5%), Hydrogen(9.5%), Nitrogen (3.2%), Calcium (1.5%), Phosphorus(1.0%), Potassium(0.4%), Sulfur (0.3%), Sodium(0.2%), Chlorine(0.2%), Magnesium (0.1%) because they are reasonably plentiful. So that's mostly what living things are made of. You get some things like iron in hemoglobin, but iron is ~1/20,000th of a persons body weight and heavily recycled. Yet, iron deficiency is still a common issue.

digi_owl2• 9 years ago

On that note, i recall hearing about an iron fish various health orgs have been distributing in poorer nations.

This because as households switched out their old iron pots with modern ones, there has been an uptick in deficiencies.

pmontra3• 9 years ago

I'd rule out the gray ooze scenario. Those bacteria will replicate but they won't be able to generate new cadmium based semiconductors. New bacteria outside the tank will be just normal bacteria.

pasta• 9 years ago

So in the near future we might dump our trash into our cars for fuel [1].

[1] http://backtothefuture.wikia.com/wiki/Mr._Fusion

meri_dian2• 9 years ago

"The hybrid organism, M. thermoacetica-CdS, produces acetic acid from CO2, water and light."

I love bacterial and algal based approaches to fuel generation. Re-purposing nature's own highly advanced (relative to our own state of the art) chemical processing machinery seems an easier path forward than building our own from scratch.

That said, relying on a fuel source that requires CO2 as input seems just as potentially destabilizing to the global carbon cycle as relying on a fuel source that produces CO2 as byproduct.

yorwba• 9 years ago

That said, relying on a fuel source that requires CO2 as input seems just as potentially destabilizing to the global carbon cycle as relying on a fuel source that produces CO2 as byproduct.

You mean like wood? Burning that fuel releases the same amount of CO2 back into the atmosphere; the end-to-end process is carbon-neutral.

meri_dian2• 9 years ago

The end to end process of burning coal is also carbon-neutral according to that logic, yet it seems to be causing some trouble.

imaginenore• 9 years ago

Burning wood becomes carbon-neutral only after you grow that amount of wood (and in dry weight).

adrianN2• 9 years ago

As long as you make sure to burn the fuel and don't store gigatons of it somewhere safe I see no problem.

pmontra3• 9 years ago

We are having an excess of CO2 in the atmosphere right now. Using it to generate useful stuff looks ok to me. Water could be a problem.

vkou• 9 years ago

If we were to lose all the CO2 in the atmosphere, we will all very quickly die. Plants require it to survive. [1]

The problem with bacteria, is that thanks to exponential growth, and an inability to control them, we can end up in deep, deep trouble. Using them in a controlled fashion that will bring us from 400ppm to 250ppm (but no lower) seems incredibly unlikely. Either they won't be able to make a big difference, or they'll bring us to a level far below habitable.

[1] https://en.wikipedia.org/wiki/Future_of_Earth

deegles• 9 years ago

Just put one gallon in an old oil well for every gallon we burn.

subnaught3• 9 years ago

That said, relying on a fuel source that requires CO2 as input seems just as potentially destabilizing to the global carbon cycle as relying on a fuel source that produces CO2 as byproduct.

Not really. Using CO2 to generate a fuel which then liberates CO2 when it is consumed ends up being CO2-neutral, which is exactly the way to go.

_0w8t2• 9 years ago

Once more efficient capture of solar energy by single-cell organisms wiped out probably 95% of life forms on Earth [1]. Have we learned the lesson?

[1] http://www.slate.com/blogs/bad_astronomy/2014/07/28/the_grea...

leggomylibro• 9 years ago

Just don't let them near the oceans - although that does sound like an 'ice-9' situation from a terrorism or MAD point of view.

sqeaky• 9 years ago

I wonder if these would do well in the wild? If so there is a huge ethical issue here.

I think a more likely possibility is that they might be like like most domesticated photosynthesizers. Loose populations would revert to more natural traits and become less useful to humans and barely struggling for survival.

Consider what happens when farm grown tomatoes or corn go wild. The vast majority die off because their fruit wastes a ton of energy becoming huge and visually appealing. Those with just enough fruit to entice animals to spread it, those that grow faster and those with the best resistances will succeed in the wild.

Can these bacteria benefit from these solar cells without the help of humans feeding them? If they could then natural selection will reinforce our decisions and we could have a real threat.

I agree the risk reward part of this needs careful analysis, I don't think we need to go straight to doom and gloom.

EDIT - Speeling, and grammar.

_0w8t2• 9 years ago

[1] gives example how simple selection for better use in agriculture gives big problems a few years later when the plant mutates in wild into a nasty pest. Situation is especially sad in poor regions of Russia North where lack of money in local budgets allowed the plant to spread everywhere. Driving there is like watching illustration for "The Day of the Triffids" by John Wyndham [2].

[1] https://en.m.wikipedia.org/wiki/Heracleum_sosnowskyi

[2] https://en.m.wikipedia.org/wiki/The_Day_of_the_Triffids

mattferderer• 9 years ago

If you're as inept at Chemistry as I am, I highly suggest the video in the article. I'm inept at Chemistry but this sounds fascinating. Here's my TLDR summary of this article for others like me. Please correct me if I'm misunderstanding it.

TLDR: A bacteria that can't photosynthesis sunlight is covered with semiconductors that allow it to use the sunlight. The bacteria efficiently produces an acid that can be turned into fuels, medicine, polymers & more. The bacteria can regenerate & replicate as well so there is no waste.

What I don't understand is the regenerating & replicating part. I'm assuming they take this bacteria & place the semiconductors on it. When it replicates, does the new bacteria created have these semiconductors on it as well? If so, how?

subnaught3• 9 years ago

You've got a lot of it right, but you're missing the key advance described here, which--if true--is pretty wild.

Taking a step back, in 2016, this group did cover a bacterium with tiny semiconductor nanoparticles (specifically CdS) just as you say. That work is described here: http://www.pnas.org/content/113/42/11750.full In short, the semiconductors act as mini-solar cells, converting light into electrical current. The bacteria then use that electricity to convert CO2 into acetic acid. That already is pretty cool.

However, what they claim now is that they don't even need to make the semiconductor nanoparticles. They can simply grow the bacteria in an environment containing cadmium and sulfur sources and the bacterium will synthesize it's own cadmium sulfide coat, and use it for photosensitization.

This is really pretty wild. Bacteria will often incorporate various elements from their host medium, but the generally use them to make biomolecules, not semiconductors. Right now, this is just being presented at a conference, but it will be very interesting to see the details when the full paper comes out.

spqr0a12• 9 years ago

This appears to be a based on a paper from last year. http://science.sciencemag.org/content/351/6268/74

While good and interesting work, there's a lot left to do. They're using cysteine as a reductant, so not all of the energy is coming from light. Furthermore while the system uses 90% of the cysteine and 80% of blue light, it is only 2% efficient with broad spectrum (sun-like) lighting. Even that well only under dim lighting.

Edit: Here's a group that's developed a system that's 5 times as efficient and only uses CO2 and water as feedstock rather than cysteine and cadmium. http://science.sciencemag.org/content/352/6290/1210

subnaught3• 9 years ago

That's an apples-and-oranges comparison. The system you cite differs from the one under discussion in several ways; the most important of which are:

1. The cited system does not include a light-harvesting component. It merely postulates that the required energy could be generated from photovoltaics. This would introduce additional cost and complexity along with an efficiency hit.

2. The cited system comprises a bacterium in conjuction with an electrode-supported catalyst, whereas the system under discussion is solely an engineered bacterium.

Finally, it is not correct to refer to cadmium and cysteine as feedstocks. They are components of the catalyst, and they are not consumed during catalysis. The only feedstocks for both systems are CO2 and water.

spqr0a12• 9 years ago

You're right that Liu's paper does use external electrodes. And as for Sakimoto's paper it's true that the cadmium should be reusable indefinitely, but if you read the second page it's clear than cysteine is consumed in stoichiometric amounts. I'd be excited to hear about more recent work which improves upon this and would be happy to be corrected.

f09ui• 9 years ago

The way the authors calculate the Quantum yield is by dividing estimated total number of electrons to estimated total number of photons. If you do it the way the plant and algae people do it(divide the total number of carbon to the total number of photons), the quantum yield of photosynthesis is now 20% (in plants and algae you can get to 10-11%).

Also, cysteine is used as a reductant - as soon as they will try to use water as an electron donor the efficiencies will like ly to go down.

And who is going to count the energy needed for bacteria metabolism?!

Cyborg bacteria outperform plants when turning sunlight into useful compounds

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