James Smith

These fix carbon directly from sunlight and they can grow with just achiral nutrients like nitrogen, phosphorus, sulfur, that sort of thing.

And one of the very common causes of death for these marine cyanobacteria is infection by phage.

So up to 50% of marine cyanobacteria die from phage infection.

So if you introduced a mirror cyanobacterium, it would have basically these huge advantages because it wouldn't be able to be infected by phage, but potentially none of the limitations on nutrient availability.

And so the population of marine mirror cyanobacteria might grow to be very large.

If they're growing to be very large and nothing is eating them because they don't really give any nutritional value to the protists that usually consume them, then they might start to sink to the bottom of the ocean and fix more carbon.

And it's really unclear what would end up being limiting here.

So I'm not confident at all in what would happen, but it could be the case that they act as a massive carbon sink, taking a lot of CO2 out of the atmosphere.

Yeah, to me, it seems really difficult to kind of titrate the amount of CO2 that you'd be able to take out of the atmosphere in this way, because once you had this population of myrosinobacteria growing, they would be really difficult to control and they would start to evolve into into other things.

So you might think, couldn't we just control them with mirror phages that we make or something like that?

But at that stage, there'll already be a lot of them around.

It'll be impossible to drive the population to zero.

So we might just overshoot by miles and end up in an ice age or something like that.

Okay, yeah.

Equally, that might not happen.

And we might end up, I don't know, killing loads of trees through mirror bacteria and releasing loads of carbon into the atmosphere.

So depending on the mirror bacterium that's being made, it could kind of go in different directions.

It's hard to be confident, but we can look at some existing diseases and how quickly they've been able to spread as examples.

So COVID, because people spread it through air travel, was on all inhabited continents within four months of the first case.

And more generally, the speed at which a pathogen is going to spread is dependent on how quickly the fastest moving host moves around.