Has anyone done an intestinal flora test?

Someone must have tested it, otherwise how do you know which probiotics are? However, these tests are very difficult in practical work. As far as we know, there are more than 20 thousand kinds of intestinal flora, some of which are beneficial to human body, some are harmful and some are conditional pathogens. It is difficult to judge these flora. For example, it is feasible for Radix Isatidis to resist virus in vitro. There are many factors in the body. At present, there are some understandings that the intestine is the second brain of human beings, and the balance of many flora is the basis of human health. Medical institutions are doing their best to study it, hoping to gain something one day. At present, it is mainly to assist the treatment of intestinal flora. I hope to become the mainstream in the future.