List and explain the three types of respiration found in bacteria

list and explain the three types of respiration found in bacteria?
Asked Feb 21, 2010
Although we think of respiration as breathing, respiration is actually the process by which organisms break down organic substances (such as sugars) to produce energy. All living organisms must perform some kind of respiration.

In many cases, the chemical process of respiration requires oxygen, although some organisms are able to carry out respiration in the absence of oxygen. This page will explain the three types of respiration found in microorganisms, as well as how these types of respiration affect the wastewater treatment plant.

Aerobic Respiration

Aerobic respiration is respiration in the presence of oxygen. Most multicellular organisms and many microorganisms produce their energy using aerobic respiration. In aerobic respiration, sugars are broken down in the presence of oxygen to produce carbon dioxide, water, and energy. Without oxygen, aerobic microorganisms are unable to produce energy and quickly die.

Anaerobic Respiration

Other microorganisms are able to survive in environments which lack oxygen by performing anaerobic respiration , sometimes known as fermentation . Like aerobic respiration, anaerobic respiration breaks down sugars and releases energy. However, anaerobic respiration is typically slower and less efficient than aerobic respiration. In addition, anaerobic respiration involves chemicals other than oxygen and carbon dioxide.

The chemicals used and produced during anaerobic respiration vary from microorganism to microorganism. Some anaerobic microorganisms use sulfate (SO42-) during respiration and produce hydrogen sulfide (H2S.) Other microorganisms use nitrate (NO3-), producing nitrite (NO2-), nitrous oxide (NO), or nitrogen gas (N2 ). Yet other microorganisms are able to use hydrogen gas (H2 ), producing methane (CH4 ) or acetic acid (CH3COOH-) as the byproduct.

Anaerobic reactions generally lead to more offensive end products than those produced during aerobic respiration. For example, hydrogen sulfide is very reactive and smells like rotten eggs even at low concentrations. Hydrogen sulfide can combine with the organic end products of anaerobic respiration to form the dark-colored, odorous substances which are characteristic of anaerobic (also known as septic ) conditions.

Facultative Anaerobic Respiration

Many microorganisms are either obligate aerobes or obligate anaerobes. That is, those which perform aerobic respiration will die if the oxygen content of their environment drops too low. In contrast, those which perform anaerobic respiration will die if they are brought in contact with oxygen.

The final type of microorganisms - facultative anaerobes - are able to perform either aerobic respiration or anaerobic respiration depending on the oxygen content of their environment. Since aerobic respiration is more efficient, facultative anaerobes will perform aerobic respiration if there is oxygen present in their environment. However, in the absence of oxygen, these organisms simply switch over to anaerobic respiration. Coliform bacteria are a well-known example of facultative anaerobic microorganisms.

In the Treatment Plant

In most wastewater treatment processes, operators attempt to maintain an environment suitable for aerobic respiration. By maintaining an aerobic environment the operators prevent the bad smells associated with septic environments and also maintain a higher speed of waste digestion. Aerobic processes are most common in biological wastewater treatment systems, including the activated sludge process, trickling filters, and many oxidation ponds.

Since aerobic microorganisms use up oxygen as they break down waste, it is often necessary to aerate (add air to) the wastewater to maintain an aerobic environment. Aeration may be achieved by blowing air into the water or (as in the trickling filter) by allowing water to run through the air.
Despite the advantages of aerobic systems, some wastewater treatment processes are designed to be anaerobic. Both anaerobic digesters and septic tanks are wholly anaerobic environments. Since these systems house obligate anaerobic microorganisms, exposing anaerobic digestion systems to oxygen even for a short period of time can seriously affect the systems' ability to function.
Some systems, through accident or design, can function both aerobically and anaerobically. Although oxidation ponds are generally aerobic, bottom deposits and stagnant pockets in the ponds often become anaerobic. On a trickling filter's slime layer, aerobic and anaerobic zones may occur within millimeters of each other, with the surface layers being aerobic and the deeper layers being anaerobic.
Facultative anaerobic microorganism species are very important in many wastewater treatment processes since they area able to perform in both aerobic and anaerobic environments. However, facultative anaerobic microorganisms can cause problems when they begin to respire anaerobically, producing unpleasant byproducts. In general, facultative anaerobic species usually begin performing anaerobic reactions when the dissolved oxygen levels of their environment fall below about 0.5 mg/L for several hours. This condition is rarely met in aeration tanks unless equipment failure occurs, but keeping sludge in the final clarifiers for an extended period of time can lead to anaerobic conditions. In addition, conditions of low flow or elevated temperature can result in anaerobic conditions.
Answered Jun 04, 2012
It is only AEROBIC AND ANAEROBIC RESPIRATION.For the beginner students the best definition for aerobic and anaerobic is that in aerobic respiration it involves oxygen while in anaerobic respiration it do not need oxygen.
Answered Dec 03, 2014
Best for beginners
Naseer Dec 03, 2014

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