What does good bacteria create? (for example, soil)?

Question

What does good bacteria create? (for example, soil)?

Answer 1

Well, good bacteria help us in digestion, and they can make us immune to some things. They can also decompose biodegradable stuff and thus recycle nutrients in an ecosystem.

Answer 2

There are more good bacteria than bad. For example, good bacteria take nitrogen out of the air and convert it into something plants can use. These bacteria are called diazotrophs and the process is called nitrogen fixation. Plants need nitrogen and cannot make it themselves. So in a way bacteria make plants.