How do microorganisms respire?

Bacteria are small, single-cell organisms that are both beneficial and harmful to human beings. Some forms of bacteria help us to live, such as those that help to break down food in our intestines. Other forms, such as the bacteria that causes the Bubonic Plague, can kill a person if left untreated. There are many different types of bacteria and they respire using different methods. The two primary methods of bacterial respiration are aerobic respiration and anaerobic respiration.