Bacteria are single-celled organisms that help humans digest food.
Step-by-step explanation:
The symbiotic association of bacteria and human is of importance in the process of digestion. These bacterias are found in our gut, large intestine and sometimes in small intestine also. These bacteria break down big molecules into useful forms. Bacteria are also responsible for producing vitamin k2 and vitamin B in large intestine. They also help in mobilising of xenobiotics, bile and sterols.