One of your first ideas is to look at probiotics to enhance the host's normal microbiota. the use of probiotics to stimulate the normal intestinal microbiota and promote general health has gained increasing popularity in recent years. there are several ways in which our normal microbiota protects us from infection. which of the mechanisms below is not a protective mechanism of our normal microbiota?

Normal microbiota directly kill invading organisms.

Some bacteria that reside in our body are useful to combat pathogenic microorganisms. Those bacteria, like lactobacillus and E.coli, inhibit the growth of those pathogenic organisms by taking, for example, oxygen and nutrients from them, or even changing the local ph. They can also produce metabolites that make the environment impossible to live for the intruders.