Anaerobiosis is a type of metabolism in which organisms can live and reproduce in the absence of molecular oxygen. The term anaerobiosis comes from the Greek words an- (absence), aer (air), and biosis (life).
Anaerobic organisms include some bacteria and protozoa. They use anaerobic respiration to extract energy from organic compounds such as glucose without the use of oxygen. Instead, they use reducing agents such as nitrates, sulfates or carbon dioxide to oxidize organic matter and release energy.
Anaerobiosis is important in ecology and industry. For example, anaerobic bacteria participate in the nitrogen, sulfur and carbon cycles. Anaerobic digestion is also used to recycle wastewater and produce biogas from waste. However, some anaerobic bacteria can cause dangerous infections or spoil food. Therefore, understanding anaerobiosis is important for both the environment and human health.