Bacteroides ARE THE best-known family of gut bacteria and often form the dominant population. They are experts in breaking down carbohydrates, and they possess a huge collection of genetic blueprints, which allows them to manufacture any enzyme they need to accomplish that task. Whether we eat a steak, munch a large salad, or chew on a raffia doormat in a drunken stupor, Bacteroides know straight away which enzymes they need. They are equipped to extract energy from whatever we ingest.