Anaerobic bacteria

Anaerobic bacteria are organisms that are capable of surviving and growing in an atmosphere of little or no oxygen. Anaerobic bacteria can be further broken down based on their relationship to oxygen: obligate, aerotolerant or facultative anaerobe. They can be found in a variety of environments ranging from soil and water to the bodies of humans and other animals. Many anaerobic bacteria are found normally in the human body; in fact, in the intestines of humans, anaerobic bacteria outnumber aerobic bacteria 1,000 to 1.