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Comment by ABCLAW | Hacker News Reader

The most likely outcome is that the bacteria would be outcompeted by wildtype strains and fail to metabolize very much in the immediate term.

It's more likely we'd see this type of microbe used in a bioreactor style setup where plastic slurry and growth medium are fed in for decomposition.

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Not a given. If you introduce this gene into the ocean You’ve essentially introduced this into the horizontal gene transfer gene pool. This is how microbes evolve for the most part. If this enzyme confers even the slightest advantage some microbes will start using it. I really don’t see what the problem is though, we introduced a substance other organisms can’t digest and now we are introducing tools they can use to restore the balance.

The fact that you don't see the problem _is_ the problem. Fucking with ecosystems using bar napkin math is not a thing we should entertain.

I think though that the fact is that these biomes are evolving already means that irrespective of this research or its development, natural evolution is already responding.

If we stopped polluting tomorrow, which I wish we could, we would still need to get rid of the pollution already produced. If the natural biome is already responding, then that's a good thing.

We are already fucking with ecosystems with all the plastic fishing nets we are dumping in the ocean, and the microplastics that are everywhere. Obviously we shouldn't execute plans without a solid analysis, but entertaining ideas that resolve the problems we create is the first step.

You’re fucking with the ecosystem by existing. We all do. In the end we can only make a best guess estimate of what the effects of our action can be. What’s clear is inaction isn’t an option.

Not really. The horizontal gene transfer pool is local - you'll find microsystems where the plasmid or gene segment is present, but unless the gene itself provides some fitness benefit to the host, it will be outcompeted in general.

You'd expect a tiny reservoir of the gene to remain in circulation in heavily plastic polluted areas with low nutrient density, but you wouldn't expect the gene to represent a gain of function phenotypic change to the general microbe population.

When these hybrids are initially created, they'd likely be created via transfected plasmids that produce a ton of the enzyme - the fitness downside for a bacteria to produce a non-mutated version of the plasmid would be phenomenally large.

In the same way that we can create little insulin factory bacteria, our little plastic enzyme bacteria are not going to turn the world into grey goo; they're literally parasitized and weaker than wildtype at existing in the wild. If they weren't, they'd be the wildtype.

Why would they be outcompeted? Other bacteria have no reason to multiply when they can't eat the plastic they happen to be on.

Because they're using energy making an enzyme that only produces a positive impact on fitness in the event plastic is the best food source in the area. In all other cases, a leaner genome that isn't wasting energy on a useless enzyme is reproducing faster.

Even if plastic is heavily concentrated in the environment, if plastic isn't very energetically favorable to decompose, the environment will ALSO need to have a dearth of other available resources in order for the enzyme to provide a fitness benefit.

A good example of the situation is cellulose. Various animals can eat it. Yet trees continue to flourish for hundreds of millions of years since biological machinery to digest cellulose is very energetically expensive and slow.

That's a really bad example as plastics don't have defense mechanisms other than how hard they are to digest compared to other materials in the environment. Trees are alive and have multiple defenses.

And the microbe would tend to coexist with plastic, not eliminate it.

If 'bugs are evolving to eat plastic' does that not mean that the bacteria that can metabolize plastic are outcompeting wildtype strains, not the other way around?

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