What are four ways that bacteria are to people?

Four ways bacteria is helpful to people:
*1). digestive bacteria helps our body to break down, digest, and absorb the food that you take in.
*2). there are certain types of bacteria in your endocrine system which help you to fight off various diseases, sicknesses, as well as get immuned to them faster.
*3). adding on to the endocrine system, many bacteria help the realease of hormones and other things that take place in glands.  HOPE THAT HELPS??? thank you

1. helps digest food.

2.repair concrete

3.detect pollution

4. creats building materials

i hope that helps a bit!