How you create the bacteria’s?

Yogurt Making
1

Im curious about the process to create the bacteria’s.
How you do this?

2

It looks simple at first, but a lot of science is involved.
You need to pick up samples from nature. Then isolate them from the other bacteria, then you need to concentrate them, then freeze-drying to preserve them followed by other operations which make sure that you actually have done it right.
We have a YouTube video explaining the freeze-drying technology.
The actual method of making of bacteria is heavily protected, so any single company use their own way to make the same or almost the same or to achieve the same results using different but scientifically proven way.