How would you convince a friend that microorganisms are much more than just agents of disease?

Microorganisms that occupy the rumen of ruminant creatures is a noteworthy agrarian significance. The rumen is a microbial biological community in which substantial populaces of microorganisms process and age the polysaccharide cellulose, the real part of plant cell dividers. 
Microorganisms in the colon and stomach related procedures by incorporating certain vitamins and other basic supplements yet, in addition, vie for space and assets with pathogenic microorganisms that may enter the GI tract in sullied nourishment and water. Microorganisms assume vital parts in the sustenance business, including nourishment decay, security, and creation.

It's cell theory. easy name i would think.