Human existence would be impossible without the microorganism that surrounds us, as they play critical roles in proesses as diverse as photosynthesis, nitrogen fixation, production of vitamins in the human intestine and decomposition of vitamins in the human intestine and decomposition of organic matter. They are the sole, true „recyclers“ of oru planet. Microorganism is also the major driving force behind the evolution fo life. Some highly specialized microorganisms have adapted to harsh environmental conditions, while others, such as root-colonizing bacteria and our own intestinal flora, have taken advantage of the abundant resources provided by higher organisms.