I don't have any digestive issues, but I like the idea of having as diverse a bacterial polyculture as possible in my gut if for no other reason than to (possibly?) offer resistance against food poisoning. Additionally, I routinely see people claiming that obesity etc. can be explained by gut bacterial differences between individuals. Thinking about it objectively, a fecal transplant makes perfect sense as far as introducing anaerobes into one's gut, but let's face it, most of us will never do this.
My understanding of the initial seeding of gut bacteria is that it originally occurred during birth and was historically aided by less hygienic conditions. People take probiotics, but I seem to recall reading that none of these species actually take root and that if there is a benefit, it's transitory and dependent upon the continued consumption of the supplement.
Are there probiotics that have been formulated from species that are known to inhabit the human gut and that would actually more or less permanently take root if ingested? There'd be the problem of laboratory strains being ill-suited for an individual's gut, but these populations evolve so quickly that I think it would take care of itself if given the chance.
Do these bacteria survive on their own? If I pick some wild berries and eat them, do I ever introduce new species into my gut or do the ones I want die when exposed to air or when they are not engaged in a symbiotic relationship with a host's gut? Do the bacteria I want ever form spores and chill out until I eat them? Did we used to get exposed to these bacteria via the butchery of other animals?
I'm mostly ignorant about this subject, so if any of you gut experts can weigh in at all, I'd appreciate it.
Edit: Reading that link offered by gydle below raises the important fact that bacteria non-sexually pass around genetic material at will and that it may not be an issue of having X# of species, but rather of having the proper genes in those species you have.