What chemical changes occur with food in the intestines, what enzymes are involved in these changes?

In the intestine, the process of digestion and absorption of various substances takes place. Digestion takes place under the action of various digestive enzymes, which are produced by bacteria that live in our intestines and form the microflora. We are unable to secrete the enzymes that bacteria secrete. Therefore, there is a beneficial union (symbiosis) between humans and intestinal bacteria. Food that has not been broken down into proteins, fats and carbohydrates, which in turn has not been broken down into smaller structural units, continues to be broken down in the intestines.