Usually we think that microbes are harmful and that they impair our health. But here is an example for their good beneficial work without which our Termite (Mastotermes darwinensis) cannot live at all! Protozoan (Trichonympha) and other Microbes live in the guts of these termites and aid in the digestion of Cellulose of plant materials by secreting out the enzyme, Cellulase - to release energy from it! (Note here the fact that humans are also weak to digest cellulose!).
