Man’s relationship to bacteria is a very interesting one. We all know that many bacteria are harmful. Diseases such as typhoid fever, cholera, diphtheria, pneumonia, and all infections that occur in open wounds are each caused by a particular kind of bacteria. So man wages war on these bacteria.

Yet, without the action of other types of bacteria, life would be impossible on earth! In fact, man actually cultivates certain bacteria because he needs and uses them.