pretty sure it will live in your gut so long as you feed it enough milk and not overrun it with sugar shite that breeds competitors that kill it off

the bacteria is originally from calf intestines afaik, but it also floats around in the air nearby... not surprisingly

there's no way it survives in your gut without regular doses of lactose, that's for sure

and it's no use for anything other than digesting lactose

lactobacillus converts lactose into lactic acid, and there is a second one, that lives in a symbiosis, acidophilus, which likes the acid conditions and breaks down proteins like the hard protein casein from milk