Question

what is bacteria? why it's necessary

Answer 1

Because plants and animals can't create some of the nitrogen molecules we need to live, soilbacteria and cyanobacteria (blue-green algae) play an absolutely indispensable role in turning atmospheric nitrogen into ammonium or nitrates the forms of nitrogen that plants can absorb to create amino acids and nucleic acids, ..

Answer 2

Bacteria are microscopic, single-celled organisms that exist in their millions, in every environment, both inside and outside other organisms. Some bacteria are harmful, but most serve a useful purpose. ... Bacteria can use most organic and some inorganic compounds as food, and some can survive extreme conditions