Usefulness of microorganisms

Answer 1

Well...
They digest your food and manufacture some of the vitamins you need. (like Vit. K)
They make bread rise and turn grapes into wine.
They make yogurt and cheese.
They break down organisms that have died (animals and plants) and turn them into fertile soil.
Many plants need them to fix nitrogen from the air (and we need the fixed nitrogen from those plants)
They feed a lot of animals (like whales)
We can use them to grow drugs (like insulin)
We use them to treat illness (like penicillin)
Algae produce a significant amount of the oxygen

There are thousands of reasons that we need microorganisms, these are just a few. :)

Answer 2

Microorganisms are useful in various ways, such as in food production (like fermentation of yogurt and cheese), environmental cleanup (bioremediation of oil spills), and in medicine (production of antibiotics and vaccines). They also play a critical role in nutrient cycling and soil fertility in the environment.

Answer 3

yeast is used to make yogurt which is essential