Learn how fecal transplants are an effective treatment for Clostridium difficile colitis, in this episode of Gross Science from NOVA. Inside every person’s digestive tract are trillions of bacteria and other microbes that make up the gut microbiome. These microbial communities perform essential functions like producing molecules that your colon cells need to survive, and extracting nutrients from your food. However, when something upsets the balance of the microbes in the gut, bacteria such as C. difficile can flourish out of control, and deadly inflammations can occur. Doctors can reset the microbial balance using a fecal transplant: They place a healthy donor's fecal matter into the patient's gut to recolonize microbes and out-compete the disease-causing bacteria. This resource is part of the NOVA: Gross Science Collection.