We use heat and additional bacteria to make a cheesefrom yoghurt. Do you think the heat can kill the bacteria ?
If you say Yes why we need to use bacteria?
If you say No why not the bacteria can kill us when we feed it?

bacteria are rapidly killed at temperatures above 149°F (65°C). we need to use bacteria because We could not survive without all the bacteria living on and inside us. They act as part of our immune systems, digest foods such as dairy that we cannot break down ourselves and provide us with nutrients and minerals that we need to survive.