Symbiotic relationships are any interactions between organisms that have direct contact. One type of a symbiotic relationship is called mutualism. In mutualism, both partners receive benefits.
Although bacteria have gotten a bad rep lately, there are actually millions of bacteria living in the human intestine that are crucial to our well-being! Some of the important jobs these “gut flora” do include: breaking down food that we normally could not metabolize, helping our body identify and attack harmful organisms (including harmful bacteria), and stimulating cell growth. When we ingest antibiotics, both the harmful and the helpful bacteria end up getting killed. In order to help replenish our supply of “good” bacteria, we can eat a lot of yogurt. Yogurt is chock-full of these helpful (or probiotic) bacteria.
We can see the benefits that probiotics provide us and the other end of this mutualistic relationship is just as important. While probiotics help us live, we give them a place to live. Because both partners in this relationship are receiving positive side-effects, it is considered mutualism.