Question

why microorganisms called friend and foe

Answer 1

They are friends as well as foes of man becoz . they play an important role in industry , agriculture , and maintaining the environment clean .
however , many microorganisms cause a number of diseases in man , animals, and plants etc.

Answer 2

Microorganisms help in making curd,vinegar and alcohol.They also help in sewage treatment.This indicates that they are our friends.But the same they were for(enemy). They infect our blood and multiply inside our body.They also cause many diseases to crops and animals.So the microorganisms are considered as both friends and foe.
Hope this answer helps you.......