The eubacteria is a super class which groups different types of bacteria except for archaebacteria. Eubacteria are mostly unicellular in nature and their nucleus is not enclosed in any membrane. These heterotrophic microbes obtain nutrition from a variety of sources. Most eubacteria are pathogenic in nature. They are responsible for causing diseases like cholera, tuberculosis, typhoid and dysentery in humans. Heterotrophic eubacteria exhibit parasitic as well as saprophytic behavior. Diseases in human beings are mostly caused by infection of parasitic eubacteria. The saprophytic eubacteria derive nutrition from dead organisms and their surroundings.
Kingdom Eubacteria Examples
Examples of eubacteria and details about characteristics of these organisms can be found below. Let us study them one by one.
These eubacteria are 3-5 micrometers in length; their width is 1-1.2 micrometers. Bacillus anthracis is a Gram-positive bacterium with a rod-shaped body. Casimir Davaine and Aloys Pollender are credited with discovering the Bacillus anthracis. These bacteria synthesize a protein called D-glutamate. It is the only eubacterium capable of producing a protein capsule. TheBacillus anthracis grows in both aerobic and anaerobic environment in laboratories. Origin of the name, anthracis can be traced back to the Greek word, anthrakis. Anthrakis means coal. Infection of this bacteria causes black-colored skin lesions, which is probably the reason why Bacillus anthracis is called anthrakis.
Named after Theodor Escherichia, the Escherichia coli is a Gram negative bacterium with a rod-shaped body. The Escherichia coli O157:H7 is responsible for causing food poisoning in humans. Otherwise, these bacteria are not that harmful and do not cause any other health problem. Escherichia coli grows in the lower intestines of endotherms - warm-blooded organisms. The beneficial bacteria found in the guts of these warm-blooded animals help in obtaining vitamin K2. These beneficial bacteria also help in removing pathogenic bacteria from our body. The Escherichi coli virulent strains cause urinary tract infections, gastroenteritis and neonatal meningitis; beneficial Escherichi coli strains are used as probiotic agents for medicinal purposes.
These bacteria are Gram positive and anaerobic in nature. The Clostridium tetanibacteria possess a rod-shaped body and their gram stain appearance resembles the shape of drumsticks. Production of tetanospasmin, a biological toxin is the characteristic feature of these bacteria. They cannot survive in the presence of oxygen during the phase of vegetative growth. Locomotion takes place by means of flagella. Clostridium tetani is sensitive to heat. A cut in skin/wound is used by this pathogenic bacteria as the opening to enter the body of the host. This organism multiplies after entering the host body. Along with tetanospasmin, Clostridium tetani produces an exotoxin called tetanolysin.
These rod-shaped bacteria are obligate anaerobes in nature; which means oxygen is poisonous for them. These bacteria are found in low-oxygen conditions, mainly under marine sediments. The Clostridium botulinum forms spores to survive in adverse climatic conditions. Emile van Ermengem first identified and isolated the bacterium in 1895. Clostridium botulinum is responsible for causing botulism. In botulism, the nervous system is paralyzed by neurotoxins produced by the bacterium. Symptoms of botulism can be observed in just 12-36 hours after a person consumes food contaminated with neurotoxins.
Borrelia burgdorferi is the causal organism of Lyme disease. The bacteria is commonly found in North America. It is a pathogenic bacterium with a spiral shaped-body. The Borrelia burgdorferi is a double-membraned bacterium with two flagella. The Barbour-Stoenner-Kelly (BSK) medium is used for growing the Borrelia burgdorferi bacterium in laboratories. This bacterium belongs to the genus Spirochaetes (Spirochetes). Cells of the Spirochete bacteria are helical in shape. Spirochetes is a class of chemoheterotrophic bacteria. Their length ranges from 5-250 micrometers. These bacteria move from one place to other by means of a twisting, rotating motion; axial filaments assist the bacterium in its movements. The Borrelia burgdorferi reproduces asexually through binary fission.
This bacterium is found in the gastrointestinal tracts of humans. In fact, it is found in the upper gastrointestinal tracts. The bacterium can be found in the intestines of about 50% people in the world.Helicobacter pylori is the causal organism in 80% of the stomach ulcer cases in the world. Helicobacter pylori infection is mostly found in countries with poor sanitation. Those who are infected by Helicobacter pylori are vulnerable to developing stomach cancer. The major symptoms of infection are stomach ache and gastritis. This Gram-negative bacteria is helix-shaped; its length and diameter are 3 micrometers and 0.5 micrometers respectively.
The tolypothrix is a genus of cyanobacteria. It is grouped under the class cyanophyceae. The tolypothrix bacteria are filamentous in nature; their strands are cylindrical in shape. These bacteria are greenish, brownish or yellowish in color. The tolypothrix and bacteria from genus, Scytonema are similar in appearance. The tolypothrix bacteria grow in water bodies, however, near the shores. They are found floating in water or attached to rocks and plants. There are few species of tolypothrix bacteria which grow in alkaline water bodies. However, some of them are also found in tree barks, wet soils, wet stones, etc. The green color of tolypothrix is due to chlorophyll. Therefore, tolypothrix, like other cyanobacteria, perform photosynthesis and prepare their own food.
These Gram positive, rod-shaped bacteria are known to form spores. The Clostridium perfringens is generally found in marine sediments and areas of decaying vegetation. It may or may not be pathogenic. Clostridium perfringens infection rarely causes health problems. Otherwise, ingestion of these bacteria is generally not harmful. Infection of these bacteria can be observed in the form of diseases like necrosis, gas gangrene, emphysematous cholecystitis, bacteremia, etc. Colonies of Escherichia coli bacteria that are raised on agar plates exhibit rough and irregular margins.
The eubacteria form an important section of microbes found in nature. Most eubacteria are pathogenic in nature. However, there also are a few species which benefit the host organism. The knowledge of classification of bacteria proves to be useful in understanding more about these microbes. The eubacteria examples and their descriptions presented in the article provide some useful information on these microbes.