BACTERIA AND ARCHAEA
BACTERIA AND ARCHAEA are both prokaryotic single-celled organisms.
Archaea (Halobacterium)
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Bacteria (Chlamydomonas)
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Many of the bacteria and archaea species discovered were found to be extremophiles that thrived in harsh conditions that would have killed your average life form. Some were found to grow best at temperatures above the boiling point of water or in toxic, acidic waste. Others were found to live completely independent of sunlight or oxygen and produced methane gas.
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What Are the Main Features of Prokaryotes?
- There are two basic types of organisms. Prokaryotic and Eukaryotic.
- Single-celled prokaryotes are the smallest organisms
- All prokaryotes are in either the Bacteria or the Archaea domains of life.
- Bacteria usually contain a cell wall.
Biofilms
 Staphylococcus aureus biofilm on an indwelling catheter
Obtained from the CDC Public Health Image Library. Image credit: CDC/ Rodney M. Donlan, Ph.D.; Janice Carr (PHIL #7488), 2005.
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The discovery of biofilm was enlightening. The ability of bacteria to develop into a biofilm demonstrates a highly coordinated level of cooperation between the individual cells involved. These biofilms, though made up of thousands of cells, function as a unit and communicate to each other through chemical signaling. The cells making up the biofilm secrete proteins that become a matrix of polymers that act as an anchor to hold the bacterial cells together and adhere them to all manner of different surfaces. These sticky biofilms have been found cemented to both living and nonliving surfaces, such as plastic, metal, fiberglass, pets, plants and medical devices.
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In 1977, Carl Woese recreated taxonomy so that it would contain 3 domains instead of 2,
Domain Bacteria is made up of 5 major groups (called phyla):
- proteobacteria
- chlamydias
- spirochetes
- cyanobacteria
- gram-positive bacteria.
There are 4 classifications of bacteria based on their sensitivity.1.Gram positive
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GRAM-POSITIVE AND GRAM NEGATIVE BACTERIA
- Bacteria are divided into two groups; Gram-Positive and Gram Negative, depending on how they react with the Gram stain.
Gram-positive bacteria have a cell wall composed of THICK peptidoglycan which retains a purple/blue hue when stained with gram stain.
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Gram-positive Bacteria are found on the skin and mucous membranes.
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Gram-negative bacteria have a cell wall composed of THIN peptidoglycan which does not retain the purple dye (crysal violet) in the Gram stain. They do turn red/pink when exposed to safranin stain in Gram staining.
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Gram-negative Bacteria are found in the Gastro-intestinal tract and the urogentital tract. These bacteria are responsible for the following illnesses:
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ATYPICAL BACTERIA
Not all bacteria are able to be stained using Gram staining. Those bacteria are classified as "atypical". For example, bacteria that do not have a cell wall, are not able to be stained by the Gram stain, such as Mycoplasma and Chlamydia. Another type of atypical bacteria is Rickettsia, because they are too small to undergo staining by the Gram stain.
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Atypical bacterial infections usually occur in the respiratory and urogenital tract. Atypical bacteria cause
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Lungs Infected with Pneumonia
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Aneorobes
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Anaerobes are microbes that do not require oxygen. In fact, some types of anaerobes will die when exposed to oxygen. These types of bacteria are found in portions of the human mouth, sinuses, throat and lower bowels.
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DEEPLY-BRANCHING BACTERIA
Deeply branching bacteria are special class of bacteria that are very ancient. These bacteria are thought to be the closest living organisms to the "universal common ancestor" that is defined as the first life-form to exist on Earth. These bacteria are remarkably resilient and can withstand the harshest, most inhospitable habitats on Earth!
One example of a deeply-branching bacteria is the Aquifex. The Aquifex is are extremophiles that prefer temperatures of 85 to 95 degrees Celsius, near the boiling point of water! Aquifex means water-maker in Latin. The Aquifex got their name due to the fact that they actually create water as a byproduct of their respiration processes.
One example of a deeply-branching bacteria is the Aquifex. The Aquifex is are extremophiles that prefer temperatures of 85 to 95 degrees Celsius, near the boiling point of water! Aquifex means water-maker in Latin. The Aquifex got their name due to the fact that they actually create water as a byproduct of their respiration processes.
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Classes of Gram-Negative Bacteria Gram-negative bacteria are separated into 3 phylum.
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Proteobacteria - These bacteria include E. coli and Bordetella pertussis
Gram stain of Bordetella pertussis, the bacteria that causes whooping cough.
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E. Coli
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CFB Bacteria - this phylum includes the healthy bacteria of the human digestive tract, such as the Bacteroides.
PROTEABACTERIA ARE DIVIDED INTO 5 CLASSES
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Carl Woese discovered the archaea in the 1970's. He found that the archaea and bacteria were distinctly different from one another.
Alpha Proteobacteria
Title: Pathology: Histology: Pap Smear Description: Human pap smear showing clamydia in the vacuoles at 500x and stained with H&E.
Alphaproteabacteria are a class of gram-negative proteobacteria that are oligotrophic, which means that they can survive in habitats that provide little nutrients. Alphaproteobacteria live in extreme environments such as sediments deep in the ocean, soil deep below the Earth's surface and even inside of glacial ice.
Alphaproteobacteria is a phylum which is made of the two taxa, chlamydias and rickettsias. Both chlamydia and rickettsias are obligate intracellular pathogens, which means that they must invade a host cell in order to complete part of their life cycle. Chlamydia and Rickettsia cannot make adenosine triphosphate (ATP) so they depend solely in the ATP provided by a host cell.
Alphaproteobacteria is a phylum which is made of the two taxa, chlamydias and rickettsias. Both chlamydia and rickettsias are obligate intracellular pathogens, which means that they must invade a host cell in order to complete part of their life cycle. Chlamydia and Rickettsia cannot make adenosine triphosphate (ATP) so they depend solely in the ATP provided by a host cell.
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Rickettsia spp. includes a lot of different bacteria that causes serious illness in humans, such as R. rickettsii which causes Rocky Mountain spotted fever. Rocky Mountain Spotted Fever is a bacteria that can be spread to humans, when bitten by an infected tick. The infection causes inflammation of the delicate membranes that surround the brain (meningoencephalitis) and often leads to death.
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Rocky Mountain Spotted Fever
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Beta Proteobacteria
Gonorrhea
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Betaproteobacteria are a class of proteobacteria which are eutrophs (or copiotrophs), which means that they require a large amount organic nutrients to survive. These bacteria are important for the nitrogen cycle. Betaproteobacteria are found between aerobic and anaerobic environments like the intestines.
The betaproteobacteria includes the bacteria N. gonorrhoeae that causes gonorrhea, and N. meningitides, that causes bacterial meningitis. Several species of betaproteobacteria cause illnesses of the respratory tract including pertussis (whooping cough). |
Gamma Proteobacteria
The gamma proteobacteria class includes the species P. aeruginosa which is a highly motile, aerobic, nonfermenting bacterium. Many of these bacteria are symbiotic to humans, however, some of these can cause a number of infections in humans. P. aureginosa causes infections of the urinary tract, the respiratory tract and open wounds. These bacteria are resilient and resistant to many antibiotics.
Gamma proteobacteria class includes the family enterobacteriaceae. These are intestinal bacteria that are fermenting, facultative anaerobes. This family is made up of two categories; 1) coliforms and 2) noncoliforms.
- Coliforms are able to ferment lactose completely into acid and gas. An example of a coliform bacteria is E. Coli.
- Noncoliforms either 1) cannot ferment lactose, or 2) ferment it incompletely into either acid or gas, but not both. An example of a noncoliform bacteria is Salmonella spp., Shigella spp., and Yersinia pestis.
Delta Proteobacteria
The last class in the proteobacteria phylum is the delta proteobacteria. These bacteria are gram-negative sulfate-reducing bacteria (SRBs). However, the SRB Desulfovibrio orale does cause gum disease.
Epsilon Proteobacteria
Epsilmon probacteria include many bacteria that find their home in the digestive system of the human body. One of these, H. Pylori is the bacteria responsible for stomach ulcers.
The other four major groups of bacteria are similarly diverse. Chlamydias are pathogens that live inside host cells, while cyanobacteria are photosynthesizers that make much of Earth's oxygen. Spirochetes include both harmless bacteria and harmful ones, like the Borrelia burgdorferi that cause Lyme disease. The same is true of Gram-positive bacteria, which range from probiotic bacteria in yogurt to the Bacillus anthracis that cause anthrax.^44start superscript, 4, end superscript
Why Are Prokaryotes So Successful?
- Prokaryotic abundance reflects a rapid reproductive rate and ability to survive harsh conditions.
- Prokaryotes divide by binary fission and have the potential to reproduce very rapidly.
- Some prokaryotes can produce endospores which allow them to survive through long periods of unfavorable conditions; Some bacterial endospores have remained viable for millions of years!
- Prokaryotes divide by binary fission and have the potential to reproduce very rapidly.
Prokaryotes are super successful organisms! They are resilient and they are found everywhere!
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So far, every time a scientist exclaims that there "couldn't possibly be life in there." they were wrong!
Prokaryotes have been found in extreme environments long thought to be completely devoid of life. For example, they have been found in the complete absence water, in the absence of sunlight, in acidic hot springs, toxic underwater sea vents and even in the air itself! |
Anatomy of Bacteria
Bacteria are single-cells organisms that have existed on our planet for hundreds of millions of years.
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Bacteria are prokaryotic, which means that they lack a nucleus and membrane-bound organelles and they contain a small circular plasmid (DNA) as its genetic material. |
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Bacteria cells are exceedingly small and enormously numerous. Bacteria have been discovered in some of the most inhospitable
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3 Basic Shapes of Bacteria
COCCUS
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BACILLUS
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SPIRILLUM
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Bacteria can be categorized by their shape. Spherical or round bacteria are called "coccus". You might recognize this term as part of the names of bacterial species like Staphylococcus aureus and Streptococcus pneumonia.
Harmful Bacteria -
(Parasitic Bacteria)
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A parasitic symbiotic relationship is one in which one organism is benefited while the other organism is harmed. There are many species of bacteria that act as parasites to humans and other organisms. These parasitic bacteria are called "pathogenic", because cause diseases. The invading bacteria have mechanisms that evade the host's immune system. They then multiply and occupy space and consume nutrients at great cost to the host. In addition, these parasitic bacteria produce toxic substances (endotoxins and exotoxins) that produce symptoms of the disease in the host. |
Many species (strains) of bacteria are known to cause illnesses and disease. Some of these include cholera, syphilis, leprosy, anthrax and the bubonic plague (otherwise known as "the black death"). Developed countries combat these bacterial infections using antibiotics. Developing countries, however, still encounter millions of deaths per year due to bacterial infections such as tuberculosis. |
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Helpful Bacteria (Mutualistic Bacterial)
Bacteria are an integral (and even necessary) part of the human body. It is estimated that the human body itself consists of 10 times more bacteria cells than human cells! That comes to a whopping 100-trillion bacterial cells. The portion of our bodies that consist of these bacterial cells has been coined "the human microbiome".Humans and other animals have a mutualistic symbiotic relationship with many species of bacteria that make their home in the our mouth, nose, throat, and intestines. |
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A mutualistic relationship is beneficial to both organisms involved. In this situation, the bacteria benefit from using the host as a habitat that provides the nutrients bacteria need to survive. The human (or animal) benefits from this relationship, because the 'good' bacteria helps prevent harmful bacterial or fungal infections.
In fact, co-existing with certain bacteria is SO necessary for good heath, that a billion-dollar industry has formed providing these bacteria to consumers in the form of pills labelled "probiotics"!
Illustration Courtesy of alivebynature.com/lactobacillus-gasseri-the-weight-loss-probiotic
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Good bacteria help to defend against the invasion of bad bacteria by populating vulnerable areas (such as the mucosa of body cavities) and sequestering the available resources.
Healthy bacteria reside in the vagina that function to regulate the growth of yeast and, thereby, help protect against yeast infections.
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Bacteria reside on our skin, in our mouth, in our lungs, in our nose, on our eyelashes and in in our eyes!
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Healthy bacteria in our gut allow for the proper digestion of food, for the movement of waste through the bowels and for proper elimination of waste.
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Bacteria are Important to the Environment!
Bacteria in Decomposition (Nutrient Cycling).
One gram of soil contains up to 10 billion microorganisms.
Bacteria are important for recycling nutrients within the ecosystem. All life as we know it on planet Earth is carbon-based. Carbon and carbon-containing compounds (like organic molecules) are essential to life on Earth. When organisms die, the carbon contained within the organism must be broken down by bacteria (and fungi) into a form that can be recycled and reused. This process of decomposition releases vital nutrients back into the soil. Some species of bacteria can even process inorganic substances (substances that are not carbon-based) like methane, sulfur and hydrogen into molecules used for biological energy.
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The Nitrogen Cycle
Nitrogen is a major component of the Earth's atmosphere. Nitrogen can be transferred to the soil by precipitation and lightening. |
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Nitrates are also introduced to the soil through animal waste. Certain bacteria can convert the nitrogen into nitrates which can then be used to build biomolecules organisms depend on. |
Nitrates are also introduced to the soil during decomposition of organisms. Decomposition occurs through decomposers like bacteria and fungi. This process breaks down the components of the dead organism and returns them to the soil.
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Bacteria work to convert the nitrogen into nitrates which allows plants to grow! The plants then provide food for the consumers of that ecosystem. |
In addition to living in the ground and the water, prokaryotic microorganisms are abundant in the air, even high in the atmosphere.
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Bacteria that love salt are called "halobacteria". The halobacteria that live in the Dead Sea function to recycle the remains of dead brine shrimp into biologically useful molecules.
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Bacteria can even change their food source! In other words, they are "metabolically flexible." For example, some types of bacteria can metabolize carbohydrates, sulfates, hydrogen ion etc.
Less than 1% of bacteria are pathogenic to humans and no archaea are known to cause harm to humans.
Salmonella is a genus of bacteria belonging to the noncliform group of Enterobactericeae, Many serotypes of Salmonellacan cause food poisoning (salmonellosis), ehich causes fever, nausea, vomiting, and diarrhea.
Vocabulary
- Proteobacteria - is a phylum of gram-negative bacteria that are classified as alpha-, beta-, gamma-, delta- and epsilonproteobacteria.
- Alphaproteobacteria are oligotrophs. The taxa chlamydias and rickettsias are obligate intracellular pathogens, feeding on cells of host organisms; they are metabolically inactive outside of the host cell. Some Alphaproteobacteria can convert atmospheric nitrogen to nitrites, making nitrogen usable by other forms of life.
- Betaproteobacteria are eutrophs. They include human pathogens of the genus Neisseria and the species Bordetella pertussis.
- Gammaproteobacteria are the largest and the most diverse group of Proteobacteria. Many are human pathogens that are aerobes or facultative anaerobes. Some Gammaproteobacteria are enteric bacteria that may be coliform or noncoliform. Escherichia coli, a member of Gammaproteobacteria, is perhaps the most studied bacterium.
- Deltaproteobacteria make up a small group able to reduce sulfate or elemental sulfur. Some are scavengers and form myxospores, with multicellular fruiting bodies.
- Epsilonproteobacteria make up the smallest group of Proteobacteria. The genera Campylobacter and Helicobacter are human pathogens.