The Biochemical Properties of Enterobacter

Bacteria are typically classified by whether they require oxygen (aerobic respiration) or grow without oxygen (anaerobic respiration). The requirement for oxygen depends on which metabolic pathway bacteria use to convert sugar into adenosine triphosphate, ATP, a usable form of energy. Some bacteria are obligate aerobes or obligate anaerobes, and are limited to one metabolic pathway. However, Enterobacter species are facultative anaerobes and live in presence or absence of oxygen. In the presence of oxygen, Enterbacter species are capable of switching metabolic pathways for metabolizing energy. The biochemical processes bacteria use in energy metabolism is useful in laboratory identification of bacterial species.

Common Forms of Enterobacter

• Enterobacter cloacae, or E. cloacae and E. aerogenes are two of the more common Enterobacter species. E. cloacae is considered an opportunistic pathogen. It normally lives in animal intestines commensally aiding in the digestive process. Like E. cloacae, E. aerogenes is not normally regarded as a pathogenic species as long as it remains within an intestinal habitat. However, once Enterobacter finds route into the bloodstream, the bacteria cause infection, high fever and disease. Antibiotics are the preferred method of treatment. Enterobacter species are found in many different habitats, including soil and water.

Biochemical Process of Enterobacter Respiration

• Respiration requires oxygen to metabolize glucose to form ATP. Animals, protozoa and bacteria are life forms all capable of respiration. The process is complex. It requires energy in the form of glucose to be broken down where energy is stored chemically by adding a phosphate group to adenosine di-phosphate to form ATP. The cycle begins with a six-carbon sugar and ends with the formation of 38 ATP molecules. The presence of oxygen is required because oxygen accepts leftover hydrogen molecules and forms water.

Biochemical Process of Anaerobic Respiration

• Fermentation is a biochemical process where a six-carbon sugar is broken down to form ATP in the absence of oxygen. Fermentation is similar for anaerobic bacteria and yeast. The end products are the formation of two ATP molecules from ADP, carbon dioxide and ethanol. However, anaerobic respiration is not as ATP productive as aerobic respiration. In the presence of oxygen, Enterobacter cells are capable of producing 38 ATP, whereas only two ATP molecules are the result of anaerobic respiration.

Nitrogen Fixation is an Important Biochemical Process

• Enterobacter species living in soil are capable of a biochemical process using nitrogen. Nitrogen fixation is an important biochemical process because it converts nitrogen in the air into a useable form for plants. Atmospheric nitrogen is absorbed through bacterial cell membranes and converted to ammonia before release into the soil. Legumes have formed a commensal association with nitrogen-fixing bacteria, a reason beans are grown to replenish nitrogen-deficient soils.

The Biochemistry of Identification

• The biochemical processes that bacteria have are often used for purposes of identification. The first step in identification of bacteria is to grow cells on a plate containing nutrient media. Bacterial cells grow rapidly and appear as spots, or colonies, on the plate. Different species grow colonies of specific size and color. Glucose metabolism produces acid and gas waste in Enterobacter species. Acid and gas production are easily detected when media includes pH indicators and bubbles are observed. Enterobacter are also capable of fermentation and are grown in different media types. Identification is an important step in treatment of blood and other Enterobacter infections. The correct antibiotic treatment is necessary to stop infection from Enterobacter species.