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Useful Microorganisms:

Many vaccines are made up of bacteria or virus.
Some bacteria are living inside our intestine help in digestion.
Penicillin is an important antibiotic drug obtained from a fungus called Penicillium.
Lactobacillus is a type of bacteria responsible for converting milk into curd.

Harmful Microorganisms:
Bacteria cause many diseases.
Other diseases are also present, like malaria, sleeping sickness etc.
It also causes many poisonous foods.
This type of virus is very harmful and cause  diseases like AIDS, chicken pox.