What do resident bacteria do within the body?

Role of Resident Bacteria in human body:

The resident bacteria performs several biological functions inside the human body. They serves two major functions: nutrition and defense. They helps to digests food, absorbs nutrients, and assists with waste excretion. Also they serves as house for enormous population of microbes that help in digestion and guard against pathogenic microbes inside the human body.

the gravitational force on an object increase as the mass of an object also, im not going to report you, but this question should be under the science category, not health