Most people automatically associate bacteria with illness. However, 99 percent of all bacteria are either harmless to humans or actually helpful. For instance, we would not be able to digest food without our gut bacteria. Plants would not grow without bacteria to break down the nutrients in the soil for them. In fact, bacteria’s ability to break things down is so helpful that scientists are working on harnessing it to clear plastic, oil, and other pollution from the environment. Informative fact boxes and engaging sidebars give readers an in-depth look at these important microorganisms.