Organisms That Breathe Anaerobically

Fermentation

• Anaerobic organisms use either anaerobic respiration or fermentation. Fermentative organisms use various chemical reactions. Plants and fungi can use ethanol fermentation when they do not have oxygen. Other methods of fermentation use propionic acid, solvent, butanediol, mixed acid, butyric and Stickland fermentation. Two other processes are acetogenesis and methanogenesis. With some anaerobic organisms, the final electron receptor is an inorganic molecule like iron, nitrogen or sulfate.

Toxins

• Anaerobic organisms often produce very dangerous toxins, including botulinum and tetanus toxins. Anaerobic bacteria are more likely to make people sick than aerobic bacteria, though there are some that are harmless and live in the intestinal tract. One of the worst anaerobic bacterium is the Clostridium bacteria, which causes tetanus, botulism and gangrene. Oxygen kills this bacterium. Helpful bacterial, such as the Lactobacillus in the intestines, resist oxygen, but cannot use it.

Cultures

• Scientists have a hard time creating anaerobic cultures, making these organisms harder to study. They sometimes create containers and purge these containers of oxygen using a reaction with water, sodium borohydride and sodium bicarbonate, which remove the oxygen gas. However, this process can kill anaerobic bacteria. Thioglycollate mediums lack oxygen and contain nutrients needed by the anaerobic bacteria. The obligate anaerobes are hard to collect, since researchers struggle to transport them without oxygen contamination. Frequently, aerobic organisms destroy anaerobic bacteria.

Anaerobic Processes

• Both aerobic and anaerobic organisms break sugar down into Pyruvate through Glycolysis, creating adenosine triphosphate (ATP). At this point, aerobic and anaerobic organisms differ in how they use ATP. The organism takes glucose and converts it into ethyl alcohol or lactic acid. Then, the organism combines that with carbon dioxide, which produces energy.

Poisonous Oxygen

• Aerobic organisms, such as humans, might not realize that oxygen has toxins. People and other aerobic organisms produce enzymes that protect them from the toxins in oxygen, but anaerobic organisms lack these enzymes. They can sometimes survive short-term exposure to oxygen, but eventually, oxygen exposure will kill them.