Bacteria was made long ago, at the dawn of life. The world was like a giant soup, and from the soup of protein, fats, and nucleic acid, small single celled organisms came to exist.
If you mean how are they grown, we have to find the best conditions to grow the bacteria. This depends on it’s genetic content. Some bacteria like oxygen, some cant stand it. Some grow at body temperature, some like it hotter. Many bacteria require certain nutrients for growth, which are called essnetial nutrients, just as we need to have certain fats and amino acids, as we can’t synthesise them ourselves.
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