Funnily enough the reason why virology therapy (something the Soviets did a lot of research in cuz they didn't have good antibiotics and biotech/pharma) hasn't seen much success at scale is precisely because the body's immune system adapts too quickly. Maybe we will see more success now with AI but it will be a cold day in hell before the powers that be let any garage biohacker have access to LLMs trained on this sort of information.

Why would you modify E coli for this? Use existing gut friendly bacteria and start from those. There's a wealth of material on the genetics of probiotics.

Um... E.coli is an existing gut friendly bacteria, one of the most common ones present in at least 90% of all humans' gut biome. There are only some specific strains which are pathogenous.