Eubacterium

Eubacterium:

Eubacterium is a genus of Gram-positive bacteria in the family Eubacteriaceae. These bacteria are characterised by a rigid cell wall. They may either be motile or nonmotile. If motile, they have a flagellum. A typical flagellum consists of a basal body, filament, and hook. The long filament is the organ which helps eubacteria move.

Gram-positive bacteria have a thick proteoglycan layer and take up violet Gram stain (whereas Gram-negative bacteria have a thinner proteoglycan layer which is surrounded by a layer of immune response-inducing lipopolysaccharide, and do not take up Gram stain). Species from this genus have been isolated from women with bacterial vaginosis. The Eubacteria, also called just “bacteria,” are one of the three main domains of life, along with the Archaea and the Eukarya. Eubacteria are prokaryotic, meaning their cells do not have defined, membrane-limited nuclei. As a group they display an impressive range of biochemical diversity, and their numerous members are found in every habitat on Earth. Eubacteria are responsible for many human diseases, but also help maintain health and form vital parts of all of Earth’s ecosystems. The Kingdom Eubacteria consists of mostly heterotrophic bacteria that come in three main shapes. They are cocci (spherical), bacilli (rod shaped-as shown above), and spirilla (corkscrew shape). This kingdom is one of the two prokaryotic kingdoms. Bacteria in this kingdom have cell walls made without peptidoglycan. It is part of the Domain Bacteria.

This kingdom consists of nearly 5000 species that have been discovered till date, and this number might increase in the near future as many researches are being conducted regularly. This class of microorganism was discovered in 1982. They are present in both living as well as non living things. In this article, we will discuss the characteristics, shapes and classification of this kingdom.

Structure:

Like archeans, eubacteria are prokaryotes, meaning their cells do not have nuclei in which their DNA is stored. This distinguishes both groups from the eukaryotes, whose DNA is contained in a nucleus. Despite this structural resemblance, the Eubacteria are not closely related to the Archaea, as shown by analysis of their RNA (see below).

Eubacteria are enclosed by a cell wall. The wall is made of cross-linked chains of peptidoglycan, a polymer that combines both amino acid and sugar chains. The network structure gives the wall the strength it needs to maintain its size and shape in the face of changing chemical and osmotic differences outside the cell. Penicillin and related antibiotics prevent bacterial cell growth by inactivating an enzyme that builds the cell wall. Penicillin-resistant bacteria contain an enzyme that chemically modifies penicillin, making it ineffective. Some types of bacteria have an additional layer outside the cell wall. This layer is made from lipopolysaccharide (LPS), a combination of lipids and sugars. There are several consequences to possessing this outer layer. Of least import to the bacteria but significant for researchers, this layer prevents them from retaining a particular dye (called Gram stain) that is used to classify bacteria. Bacteria that have this LPS layer are called Gram-negative, in contrast to Gram-positive bacteria, which do not have an outer LPS layer and which do retain the stain. Of more importance to both the bacteria and the organisms they infect is that one portion of the LPS layer, called endotoxin, is particularly toxic to humans and other mammals. Endotoxin is partly to blame for the damage done by infection from Salmonella and other Gram-negative species.Within the cell wall is the plasma membrane, which, like the eukaryotic plasma membrane, is a phospholipid bilayer studded with proteins. Embedded in the membrane and extending to the outside may be flagella, which are whiplike protein filaments. Powered by molecular motors at their base, these spin rapidly, propelling the bacterium through its environment.

Within the plasma membrane is the bacterial cytoplasm. Unlike eukaryotes, bacteria do not have any membrane-bound organelles, such as mitochondria or chloroplasts. In fact, these two organelles are believed to have evolved from eubacteria that took up residence inside an ancestral eukaryote.Bacterial cells take on one of several common shapes, which until recently were used as a basis of classification. Bacilli are rod shaped; cocci are spherical; and spirilli are spiral or wavyshaped. After division, bacterial cells may remain linked, and these form a variety of other shapes, from clusters to filaments to tight coils.

 

Metabolism:

Despite the lack of internal compartmentalization, bacterial metabolism is complex, and is far more diverse than eukaryotic metabolism. Within the Eubacteria there are species that perform virtually every biochemical reaction known (and much bacterial chemistry remains to be discovered). Most of the vitamins humans require in our diet can be synthesized by bacteria, including the vitamin K humans absorb from the Escherichia coli (E. coli ) bacteria in our large intestines.

The broadest and most significant metabolic distinction among the Eubacteria is based on the source of energy they use to power their metabolism. Like humans, many bacteria are heterotrophs, consuming organic (carbon-containing) high-energy compounds made by other organisms. Other bacteria are chemolithotrophs, which use inorganic high-energy compounds, such as hydrogen gas, ammonia, or hydrogen sulfide. Still others are phototrophs, using sunlight to turn simple low-energy compounds into high-energy ones, which they then consume internally.

For all organisms, extraction of energy from high-energy compounds requires a chemical reaction in which electrons move from atoms that bind them loosely to atoms that bind them tightly. The difference in binding energy is the profit available for powering other cell processes. In almost all eukaryotes, the ultimate electron acceptor is oxygen, and water and carbon dioxide are the final waste products. Some bacteria use oxygen for this purpose as well. Others use sulfur (forming hydrogen sulfide, which has a strong odor), carbon (forming flammable methane, common in swamps), and a variety of other compounds.

Bacteria that use oxygen are called aerobes. Those that do not are called anaerobes. This distinction is not absolute, however, since many organisms can switch between the two modes of metabolism, and others can tolerate the presence of oxygen even if they do not use it. Some bacteria die in oxygen, however, including members of the Gram positiveClostridium genus. Clostridium botulinum produces botulinum toxin, the deadliest substance known. C. tetani produces tetanus toxin, responsible for tetanus and “lockjaw,” while other Clostridium species cause gangrene.

Life Cycle:

When provided with adequate nutrients at a suitable temperature and pH,E. coli bacteria can double in number within 20 minutes. This is faster than most species grow, and faster than E. coli grows under natural conditions. Regardless of the rate, the growth of a bacterium involves synthesizing double the quantity of all its parts, including membrane, proteins, ribosomes , and DNA. Separation of daughter cells, called binary fission, is accomplished by creating a wall between the two halves. The new cells may eventually separate, or may remain joined.

When environmental conditions are harsh, some species (including members of the genus Clostridium ) can form a special resistive structure within themselves called an endospore. The endospore contains DNA, ribosomes, and other structures needed for life, but is metabolically inactive. It has a protective outer coat and very low water content, which help it survive heating, freezing, radiation, and chemical attack. Endospores are known to have survived for several thousand years, and may be capable of surviving for much longer, possibly millions of years. When exposed to the right conditions (presence of warmth and nutrients), the endospore quickly undergoes conversion back into an active bacterial cell.

DNA:

Most eubacteria have DNA that is present in a single large circular chromosome. In addition, there may be numerous much smaller circles, called plasmids . Plasmids usually carry one or a few genes. These often are for specialized functions, such as metabolism of a particular nutrient or antibiotic.

Despite the absence of a nucleus, the chromosome is usually confined to a small region of the cell, called the nucleoid , and is attached to the inner membrane. The bacterial genome is smaller than that of a eukaryote. For example, E. coli has only 4.6 million base pairs of DNA, versus three billion in humans. As in eukaryotes, the DNA is tightly coiled to fit it into the cell. Unlike eukaryotes, however, the DNA is not attached to histone proteins.

 

Much of what we know about DNA replication has come from study of bacteria, particularly E. coli, and the details of this process are discussed elsewhere in this encyclopedia. Unlike eukaryotic replication, prokaryotic replication begins at a single point, and proceeds around the circle in both directions. The result is two circular chromosomes, which are separated during cell division. Plasmids replicate by a similar process.

Gene Transfer:

While bacteria do not have sex like multicellular organisms, there are several processes by which they obtain new genes: conjugation , transformation, and transduction. Conjugation can occur between two appropriate bacterial strains when one (or both) extends hairlike projections called pili to contact the other. The chromosome, or part of one, may be transferred from one bacterium to the other. In addition, plasmids can be exchanged through these pili. Some bacteria can take up DNA from the environment, a process called transformation. The DNA can then be incorporated into the host chromosome.

 

Some bacterial viruses, called phages, can carry out transduction. With some phages, the virus temporarily integrates into the host chromosome. When it releases itself, it may carry some part of the host DNA with it. When it goes on to infect another cell, this extra DNA may be left behind in the next round of integration and release. Other phages, called generalized transducers, package fragments of the chromosome into the phage instead of their own genome . When the transducing phage infects a new cell, they inject bacterial DNA. These phages lack their own genome and are unable to replicate in the new cell. The inserted bacterial DNA may recombine (join in with) the host bacterial chromosome.

Nutrition:

A great many of the most familiar eubacteria are heterotrophs, meaning they must take food in from outside sources. Of the heterotrophs, the majority are saprophytes, which consume dead material, or parasites, which live on or within another organism at the host’s expense.

In addition to the heterotrophs, there are many kinds of autotrophic bacteria, able to produce their own food. These autotrophs may be photosynthetic or chemosynthetic and may or may not use oxygen in their synthetic pathways. Cyanobacteria are the largest group of photosynthetic eubacteria. The cells of these bacteria are often much larger than other bacteria, which in the past led this group to be classified as algae rather than bacteria. In fact, cyanobacteria are still sometimes referred to as blue-green algae. These eubacteria possess pigment molecules, including chlorophyll a, the same type of chlorophyll found in higher plants. Unlike plants, in cyanobacteria the pigments are not contained within membrane-bound chloroplasts.

Oxygen Requirements:

Respiration of eubacteria may be aerobic or anaerobic. The anaerobes undergo a form of respiration called fermentation. Among anaerobes, some can live in the presence or absence of oxygen. These are called facultative anaerobes. Some are indifferent to the presence of oxygen, but others have two respiratory pathways, one that uses oxygen and one that does not. The other group of anaerobes, the obligate anaerobes, are actually poisoned in the presence of oxygen.

 

Gram Staining:

In addition to respiratory and nutritional habits, one other important feature used to classify bacteria is Gram staining. Gram’s stain will highlight peptidoglycan if it appears in a cell wall. Not all groups of eubacteria have peptidoglycan, so all eubacteria may be classified as either Gram-positive (able to bind Gram’s stain) or Gram-negative (unable to bind Gram’s stain).

A unique group of eubacteria that bears mentioning is the mycoplasmas. Classified as Gram-positive based on their relatedness to other Gram-positives, because mycoplasmas lack a cell wall they are functionally gram-negative. Mycoplasmas are both the smallest eubacteria and the smallest organisms capable of independent reproduction. They are barely larger than some viruses. Mycoplasmas have an extremely simple cell structure, a small genome, and are therefore of special evolutionary interest.

As we just saw, eubacteria are extremely diverse and specialized to their environments. Surprisingly, the structure of most eubacterial cells is relatively simple. Rather than the complex chromosomes consisting of protein and DNA found in plants and animals, eubacteria have prokaryotic chromosomes, which are smaller and have fewer associated proteins. Eubacteria also have circular DNA molecules called plasmids. Prokaryotic chromosomes and plasmids are not housed in a centralized nucleus because eubacteria, as prokaryotes, lack a nuclear membrane. Instead, plasmids are usually found in relatively clear areas in the cytoplasm called nucleoids. The rest of the cytoplasm is filled with ribosomes, the cell’s protein synthesis machinery. While eubacteria lack the organized organelles found in eukaryotic cells, many eubacteria have specialized internal membranes. For example, cyanobacteria have membranes that contain chlorophyll and other chemicals required to carry out photosynthesis.

Many eubacteria have cell walls that lie outside of their plasma membranes. These are similar to the cell walls found in plants and fungi, but are composed of peptidoglycan rather than cellulose or chitin. In some eubacteria, this cell wall is covered by another layer called the outer membrane. Many eubacteria have yet another coating layer called a capsule. It is composed mostly of complex sugars and serves to protect the cell against environmental dangers, such as attack by host immune defenses or dehydration.

Motility:

Many eubacteria are motile. In most cases, rotating structures called flagella enable them to move. The term flagella is also used to refer to similar motility structures in protists and other eukaryotic cells, but the two are not the same and should not be confused. Prokaryotic flagella are composed of protein subunits called flagellin, while eukaryotic flagella are made of arrays of microtubules made of tubulin. Prokaryotic flagella are anchored in the plasma membrane and move in a spiral motion. Eukaryotic flagella are enclosed by the plasma membrane and can only move by beating back and forth. Exceptions to this structure of prokaryotic flagella are found in some species of spirochetes, whose flagella resemble those of eukaryotes. It is believed that eukaryotes may have developed flagella through symbiotic relationships with these spirochetes.

Shape:

Eubacteria are often classified by their shape. They fall into three main shape categories. Spherical eubacteria are called cocci; rod-shaped eubacteria are known as bacilli; spiral or helically-shaped eubacteria are spirilla.

Unlike eukaryotic cells, which divide by mitosis or meiosis, eubacteria reproduce by binary fission. In this process, the genetic material is replicated, and the two copies move to separate nucleoid regions. Next, the plasma membrane pinches inward, producing two equal daughter cells. While these daughter cells are completely independent of each other, in some species they remain together, forming colonies and filaments. Binary fission can take place very rapidly, on the order of about one split every 20 minutes, accounting for the amazing replicative ability of eubacteria.

Gene Regulation And Protein Synthesis:

Gene expression in many bacteria is regulated through the existence of operons. An operon is a cluster of genes whose protein products have related functions. For instance, the lac operon includes one gene that transports lactose sugar into the cell and another that breaks it into two parts. These genes are under the control of the same promoter , and so are transcribed and translated into protein at the same time. RNA polymerase can only reach the promoter if a repressor is not blocking it; the lac repressor is dislodged by lactose. In this way, the bacterium uses its resources to make lactose-digesting enzymes only when lactose is available.

Other genes are expressed constantly at low levels; their protein products are required for “housekeeping” functions such as membrane synthesis and DNA repair. One such enzyme is DNA gyrase, which relieves strain in the double helix during replication and repair. DNA gyrase is the target for the antibiotic ciproflaxin (sold under the name Cipro), effective against Bacillus anthracis, the cause of anthrax. Since eukaryotes do not have this type of DNA gyrase, they are not harmed by the action of this antibiotic.

As in eukaryotes, translation (protein synthesis) occurs on the ribosome. Without a nucleus to exclude it, the ribosome can attach to the messenger RNA even while the RNA is still attached to the DNA. Multiple ribosomes can attach to the same mRNA, making multiple copies of the same protein.

The ribosomes of eubacteria are similar in structure to those in eukaryotes and archaea, but differ in molecular detail. This has two important consequences. First, sequencing ribosomal RNA molecules is a useful tool for understanding the evolutionary diversification of the Eubacteria. Organisms with more similar sequences are presumed to be more closely related. The same tool has been used to show that Archaea and Eubacteria are not closely related, despite their outward similarities. Indeed, Archaea are more closely related to eukaryotes (including humans) than they are to Eubacteria.

Second, the differences between bacterial and eukaryotic ribosomes can be exploited in designing antibacterial therapies. Various unique parts of the bacterial ribosome are the targets for numerous antibiotics, including streptomycin, tetracycline, and erythromycin.

The taxonomic classification of Venenivibrio stagnispumantis is:

Kingdom: Eubacteria

Phylum: Aquificae
Class: Aquificae
Order: Aquificales
Family: Hydrogenothermaceae
Genus: Venenivibrio
Species: stagnispumantis

The taxonomic classification of Thermotoga maritima is:

Kingdom: Eubacteria

Phylum: Aquificae

Class: Aquificae
Order: Aquificales
Family: Hydrogenothermaceae
Genus: Venenivibrio
Species: stagnispumantis

The taxonomic classification of Nitrospira moscoviensis is:

Kingdom:Eubacteria
Phylum:Nitrospirae
Class: Nitrospira
Order: Nitrospirales
Family: Nitrospiraceae
Genus: Nitrospira
Species: moscoviensis

The taxonomic classification of Chlorobium limicola is:

Kingdom: Eubacteria
Phylum: Chlorobi

Class:Chlorobia
Order: Chlorobiales
Family: Chlorobiaceae
Genus: Chlorobium
Species: limicola

The taxonomic classification of Bacillus alcalophilus is:

Kingdom: Eubacteria
Phylum: Firmicutes
Class: Bacilli
Order: Bacillales
Family: Bacillaceae
Genus: Bacillus
Species: alcalophilus

Characteristics of Eubacteria:

Eubacteria, or microorganisms lacking a defined membrane nucleus, have several general characteristics. All are enclosed by a cellular wall, which is made up of peptidoglycans in a cross-linked chain pattern. This gives the wall of the bacteria the strength needed to maintain its shape and size during changing environments. Small molecules can diffuse through the cell wall, but often a proton gradient must first be established in order for molecule exchange to properly occur. Unlike eukaryotes, bacteria have cholesterol present in the membrane to enhance permeability properties of the membrane and increase stiffness. Similar to eukaryotes, bacteria also have a plasma membrane within the cell wall. Some bacteria may have a flagella, or a projection composed of protein filaments, that is used for movement. Other bacteria may have pili, which are small projections all over the outside of the cell, and are used for sticking to surfaces and transferring DNA. When a large amount of bacteria are attached to a surface and are surrounded by a polysaccharide sac, this is referred to as a biofilm. This complex has high antimicrobial resistance.

Within the plasma membrane of the bacteria is the cytoplasm, or the intracellular milieu. It is composed of mainly water (approximately 80%), but has a gel-like consistency. Bacteria do not have membrane-bound organelles, unlike eukaryotes, which have mitochondria and chloroplasts. There are ribosomes, however, which are organelles that are composed of RNA and used for protein synthesis. Free floating within the cytoplasm is also the genome, or bacterial DNA, found in the nucleoid. Bacterial chromosomes are often circular but can also be linear in shape. This shape comes in handy when a bacterium is undergoing replication. Bacteria can asexually reproduce through binary fission or budding. Binary fission is when two equal progeny cells are produced. Bacteria that undergo binary fission must first elongate before separating. Budding is when there is growth off the parent cell. Binary fission produces two equal daughter cells, while budding produces a new cell while the parent cell remains.

During times of extreme conditions not conducive to replication, such as starvation, eubacteria have the ability to become endospores. In this state, the bacteria can tolerate exceedingly high and low temperatures, acidic and basic conditions, and large amounts of radiation. Endospores are extremely hard to kill. Surprisingly, they can be boiled for hours and still survive. Endospores can only be made by Gram-positive bacteria. Within the endospore remains the bacterial DNA, but the cytoplasm has a decreased water concentration. This is thought to help in protecting against high heat. The bacteria will take on a tough coating composed of calcium and dipicolinic acid, creating a dense and impregnable barrier to stabilize the DNA within the cell. DNA repair enzymes are also still active, aiding in the resistance of the endospore.

Plasmids are also found within bacteria separate from the bacteria’s circular DNA. Also referred to as “replicons”, plasmids are autonomous replicating DNA molecules. Not all plasmids replicate in bacteria, though. These elements allow for horizontal gene transfer, which is a way for a bacterium to gain new genes and therefore traits. They primarily aid in the rapid mutation in bacteria to several factors. Similar to the other genetic material, the plasmids can be passed onto daughter cells during replication. They are the common DNA structure used in research because they are relatively easy to manipulate, implant and measure.

 

Types of Eubacteria:

Eubacteria are typically classified into five different phylums: Chlamydias, Cyanobacteria (Blue-green algae), Gram-positive bacteria, Proteobacteria, and Spirochetes. Chlamydias are often parasitic bacteria. Cyanobacteria are most commonly known to be aquatic and obtain energy via photosynthesis. Some, but not all, bacteria have an additional layer enclosing the cell wall referred to as the lipopolysaccharide or LPS layer. This extra layer cannot be dyed with a Gram stain that is often used to classify bacteria by researchers and are thus referred to as Gram-negative bacteria or Proteobacteria. Proteobacteria make up the second largest group of bacteria and they can be stained by the dye. These bacteria are referred to as Gram-positive. Spirochetes are long, thin, spiral shaped bacteria that are known to cause Lyme disease. They are distinct from the other types of bacteria due to their helical shape and movement. They typically move by spinning along their axis.Bacteria commonly take on one of three shapes: bacilli, cocci, and spirilli. Bacilli have a rod shape, cocci have a spherical shape, and spirilli have a spiral or wave shape. Their shape was often used as a classification system until recently. Bacteria may stay linked after division, forming other shapes such as clusters, filaments, and tight coils.

 

Examples of Eubacteria:

Escherichia coli, abbreviated to E. coli, belongs to the Eubacteria domain. It is classified into the Proteobacteria phylum. It is rod-shaped and Gram-negative so it has the additional membrane. E. coli is commonly found in the gut of many different types of warm-blooded hosts, including humans. Most strains are harmless, but some can cause food poisoning and other illnesses. The bacteria can only survive outside of a host for a limited time.

Streptococcus pneumoniae, abbreviated to S. pneumoniae is another common eubacteria. It belongs to the Firmicutes phylum. It is cocci shape, as its name implies, and Gram-positive. S. pneumoniae can be found on healthy hosts in the respiratory tract, nasal cavity, and sinuses. However, the bacteria can become pathogenic and spread to other parts of the body, often causing pneumonia and meningitis in immunocompromised hosts. The bacteria in high amounts can cause other illnesses as well, including, but not limited to, bronchitis, acute sinusitis, and sepsis.

Classification

Eubacteria were previously under the kingdom ‘Monera’ which also included Archaebacteria. But later, due to the differences between these two taxonomies and large number of eubacteria, they were separated and a new kingdom was created with the name Eubacteria. These bacteria can be classified into three main phyla and the characteristic features of each species can be differentiated on the bases of these categories. They are as follows.

  1. Cyanobacteria Phyla: This category has those bacteria which contain chlorophyll pigment. They can make their own food and are found in both land and ocean. They lack flagella.
  2. Spirochetes Phyla: This category consists of bacteria which move in a twisting motion. They have flagella which help them move. Some of these eubacteria may cause dangerous diseases.
  3. Proteotic Bacteria Phyla: This phylum consists of bacteria which can move either with the help of their flagella or by gliding. Most of the eubacteria are anaerobic under this category. Some are helpful while some can cause serious diseases.

Shape and Structure

Eubacteria are unicellular organisms. They can also be classified according to their shape and are found in three different shapes. Following are the shapes and examples of some of the eubacteria.

  1. Round or Spherical or Oval Shaped: Micrococcus, Streptococcus and Sarcina.
  2. Rod Shaped: Lactobacillus, Bacillus and Pseudomonas.
  3. Spiral or Comma Shaped: Vibrio, Camphilovextor and Triponema.

Structure of these bacteria depend upon their shape and type. The general structure of an eubacteria consists of a rigid cell wall which holds all the organelles inside it. The wall is made up of amino acids and a sugar chain. Some even have a membrane outside their cell wall. Penicillin resistant eubacteria have a special component in their cell wall, which reacts with this antibiotic and makes it ineffective.

The cell wall is lined with a plasma membrane from the inner side of the wall, and in some eubacteria the flagella is connected with this plasma membrane. The cell is filled with cytoplasm which consists of other cell organelles like single cell chromosome and ribosomes. The most important point which makes them prokaryote is the absence of nucleus. The reproduction in most of the eubacteria is done by binary fission, but some also reproduce by budding.

Eubacteria Kingdom Facts

Eubacteria can be present anywhere and everywhere. They can grow and flourish very fast. Following are some of the facts about eubacteria which help you to understand this living organism more closely.

  • They can survive in extreme conditions like in the areas of volcanic activities.
  • They are considered as plants because of the presence of chlorophyll.
  • Some eubacteria are considered as helpful bacteria. For instance, lactobacillus helps in the formation of curd. This eubacteria is rod shaped and is beneficial for human health. Apart from this, there are many which help in the making cheese and pickles.
  • Nitrogen fixing eubacteria helps in the process of nitrogen fixation which helps in maintaining the appropriate nitrogen level in the atmosphere.
  • They live in raw meat, raw milk, human intestine, sewage water, etc.
  • Eubacteria derive nutrition from three major sources, viz. sunlight, organic and inorganic components.
  • Some eubacteria are harmful and can cause meningitis, cholera, typhus, lyme’s, salmonellosis, tetanus, tuberculosis, etc.
  • Some of the eubacteria examples are Bacillus anthracis, Escherichia coli, Clostridium perfringens, Clostridium tetani, etc.

With this information, we can say that the eubacteria kingdom is an important part of living organisms. Though there are some species that may cause harm to the human body, this bacteria phylum is definitely an important part of our ecosystem.

Interesting Eubacteria Facts:
Eubacteria can be spherical (cocci), spiral (spirilla), tightly coiled (spirochaetes) or rod-shaped (bacilli) and 0.5 to 5 micrometers long.
Eubacteria can be found as individual cells or in the large colonies shaped like tight coils, grape-like clusters, filaments and thin biofilms.
Some Eubacteria are equipped with cilia and flagella which are used for movement.
Eubacteria do not have nucleus and cell organelles. They have single circular DNA and numerous plasmids (small circular pieces of DNA) in cytoplasm and cell wall made of chains of peptidoglycan. Additional layer of lipids and sugar around the cell wall can be found in Gram negative bacteria (term “negative” refers to their inability to absorb Gram stain that is used for dyeing of bacteria). This type of bacteria is harmful for humans and animals due to potent toxin (endotoxin) incorporated in the lypopolysaccharide layer.
Eubacteria can be autotrophic (able to produce food on their own) or heterotrophic (they consume organic compounds produced by other organisms).
Some Eubacteria metabolize (“digest”) remains of plants and animals and release valuable nutrients into the ground.
Nitrogen-fixing Eubacteria absorb atmospheric nitrogen and convert it into nitrates, plant-friendly form of nitrogen.
Eubacteria are used in the manufacture of cheese, curd, yogurt, soy sauce, vinegar and wine and for pickling.
Eubacteria in the human guts play important role in digestion of food and synthesis of vitamin K. They also protect human body from harmful bacteria.
Some Eubacteria can induce serious diseases such as tuberculosis, meningitis, anthrax, leprosy, cholera and tetanus.
Antibiotics disrupt normal functioning of bacterial ribosomes or synthesis of the cell wall and prevent further multiplication of bacteria in the body.
Most species of Eubacteria can survive either in aerobic or anaerobic conditions, while some species tolerate atmosphere both with and without oxygen.
Eubacteria reproduce asexually, via binary fission (separation of daughter and mother cells via cell wall). They exchange DNA material via hair-like projection called pili (in a process called conjugation), absorb DNA from their environment (in a process called transformation) and alter existing DNA by incorporating bacteriophage into the chromosome (in a process called transduction).
Under optimal conditions Eubacteria can produce 4 generations in 20 minutes.
Some Eubacteria form endospores under unfavorable environmental conditions. Endospores can last millions of years (until conditions improve).

 

 

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