I think this is a fairly simple question, but I'm interested in such research. If you heat yogurt in the microwave, will the bacteria in it die or not? I understand that this is a very simple question, so don't laugh, but I didn't find the answer. Some people think that the bacteria will die and the milk will lose its beneficial properties, others think that everything will be fine, what do you think? I also wanted to add at the same time why the immune system does not kill beneficial bacteria in our intestines? If the second question is difficult then just give a link to a book on the subject.

If you heat the medium in which the bacterial are (e.g. yoghurt) sufficiently high, they will die. The intestine is physiologically outside of our bodies (our whole food intake and digestion tract is basically like a kind of hose that goes goes through our bodies. Interaction with the immune system only happens fairly close to the intestinal walls (with some exceptions).

Microwave treatment can indeed kill bacteria tho' a brief exposure such as heating yogurt prob will not eliminate all viability.  Be aware - microbial populations in commercial yogurts are unstable and decrease of viable counts are common to the point that claimed benefits are more hype than substance.

It depends on how hot you get them and for how long.
it does not depend on whether you heat them in a microwave or not.