Functions of bacterial flora in human gut

Question

What are the main functions of the bacterial flora within the human gut?

Answer 1

Bacteria which reside in the gut are really important for digestion. Some polysaccharides such as cellulose, pectin and hemicellulose are not digested by digestive enzymes released by the body; otherwise, they are broken down by the enzymes secreted by bacteria of gastrointestinal tract. Intestinal bacterial flora makes essential substances for the functioning of bowels facilitating and blocking the absorption of nutrients and stimulating or decreasing the peristalsis. Some gut bacteria are main source of vitamin K for body and thus they are necessary for the process of the blood clotting. In the intestinal flora there exist utile but it is potentially damaging bacteria. It is estimated that normally more than 100 trillion bacteria live in the human gut. Some of the bacteria are useful too since they compete with the other species avoiding the excessive proliferation of these bacteria.