Our understanding of the gut microbiome is really primitive, we really don't know what a great one looks like. More problematic is that quite a lot of the bacteria that are critical die in the presence of oxygen and are thus very hard to collect and reintroduce. So far no one has made a mechanism to keep them alive and reintroduce them into other people. I would not be quick to rush to a fake biome just yet, it will almost certainly be lacking in a whole range of areas.

That’s the problem of unculturable species that pervades microbiology and anything related like agriculture. We have no idea what percentage of bacteria species can even survive long enough to be studied in the lab let alone industrialized. Even if someone manages to grow them accidentally, we’d never know it because if they don’t absorb any of the known stains, it’ll just look like agar on a plate under a microscope.

Last I checked the “state of the art” was to use a freaking electron microscope and hope that the plating process didn’t destroy the sample.

Just shooting from the hip, I'm going to guess that deliberately destabilizing ecosystems that aren't known to be unhealthy is generally not going to make them more healthy.

I wouldn't say that it's impossible to come up with some sort of microbial suppository that can take a healthy (for the host) microbiome and make it even more beneficial to the host. But, given the level of inter-person diversity in gut flora, I can't think of any particular reason to believe that it's likely that there's some universal treatment that would be beneficial to everyone regardless of their existing flora.

I am not totally ignorant of this subject, but I'd be concerned about the unknowns involved in messing around with the very long term coevolution of gut biomes with particular diets, groups of people, and factors we might not know about yet. For one example, I don't believe that that gut viromes, the ecosystem of viruses that infect the gut biome bacteria, are very well understood.

There is real wisdom in "do no harm" as a principle. It would be a lot better for most people to lose weight, eat more fruits and vegetables, spend more time outdoors, and sleep more before they consider a prophylactic fecal transplant.

I'm afraid I think the long term coevolution of gut biomes ship sailed around the time we started indiscriminately slaughtering those gut biomes with antibiotics. (not to mention importing large numbers of unfamiliar alternatives through changes in food systems, and at least in some cases raising kids in crazy-sterile environments). So I tend to agree with you that this doesn't seem like a good thing to rush into, but it's interesting as a possible form of repair.

The huge amounts of preservative used in our food chain has been even more devastating to our biome because we consume them continuously.