Cyborg bacteria outperform plants when turning sunlight into useful compounds

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.

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.

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.

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

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.

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.

Higher organisms.

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.

> 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.

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

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.

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

>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.

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.

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.