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Microbiology Written Report Bacteria Essay

Origin and Early Revolution: The ancestors of modern bacteria were unicellular microorganisms that were the iris forms of life to appear on Earth, about 4 billion years ago. For about 3 billion years, all organisms were microscopic, and bacteria and Archie were the dominant forms of life. Morphology: Bacteria display a wide diversity of shapes and sizes, called morphologies. Bacterial cells are about one-tenth the size of eukaryotic cells and are typically 0. 5- 5. 0 micrometers in length.

However, a few species -? for example, Atmospheric ambience’s and Populisms fishbone -? are up to half a millimeter long and are visible to the unaided eye; E. fishbone reaches 0. 7 mm. Among the smallest bacteria are members of the genus Macrocosms, which measure only 0. 3 micrometers, as small as the largest viruses. Some bacteria may be even smaller, but these ultraconservative are not well-studied. Most bacterial species are either spherical, called Cisco (sing. Cuscus, from Greek kГ¬∂kooks, grain, seed), or rod-shaped, called bacilli (sing. Calculus, from Latin bacillus, stick). Elongation is associated with swimming. Some bacteria, called brio, are shaped like slightly curved rods or comma-shaped; others can be spiral-shaped, called spiral, or tightly coiled, called spirochetes. A small number of species even have tetrahedral or cuboids shapes. More recently, bacteria were discovered deep under Earth’s crust that grow as branching filamentous types with a star-shaped cross-section. The large surface area to volume ratio of this morphology may give these bacteria an advantage in nutrient-poor environments.

This wide variety to shapes is determined by the bacterial cell wall and cytokines, and is important because it can influence the ability of bacteria to acquire nutrients, attach to surfaces, swim through liquids and escape predators. Many bacterial species exist imply as single cells, others associate in characteristic patterns: Engineers form diploids (pairs), Streptococcus form chains, and Staphylococcus group together in “bunch of grapes” clusters. Bacteria can also be elongated to form filaments, for example the Scatterbrain. Filamentous bacteria are often surrounded by a sheath that contains many individual cells.

Certain types, such as species of the genus Anaconda, even form complex, branched filaments, similar in appearance to fungal micelle. Cellular Structure: Intracellular Structure: The Plasma Membrane: a thin structure lying inside the cell wall and enclosing he cytoplasm of the cell. Consists primarily of phosphoric which are the most abundant chemicals in the membrane, and proteins. Cytoplasm: refers to the substance of the cell inside the plasma membrane. Cytoplasm is about 80% water and contains primarily proteins (enzymes), carbohydrates, lipids, inorganic ions, and many low-molecular-weight compounds.

The Nuclear Area: or nucleoli, of a bacterial cell contains a single long, continuous, circularly arranged thread of double-stranded DNA called bacterial chromosome. This is the cell’s genetic information, which carries all the information required for the cell’s structures and functions. Ribosome: functions as the sites of protein synthesis. Cells that have high rates of protein synthesis, such as those that are actively growing, have a large number of ribosome. Extracurricular Structure: Coaxially: (meaning sugar coat) is the general term used for substances that surround cells.

The bacterial coaxially is viscous, gelatinous polymer that is external to the cell wall and composed of polysaccharide, polypeptide or both. Flagella: (meaning whip), which are long filamentous appendages that propel bacteria. (For motility/locomotion) Axial Filaments: Spirochetes are group of bacteria that have unique structure and motility. Spirochetes move by means of axial filaments, or endothelial, bundles of fibrils that arise at the ends of the cell beneath an outer sheath and spiral around the cell. Familiar: occur at the poles of bacteria cell, or they can be evenly distributed over the entire surface of the cell.

Pill: usually longer than familiar and number only one two per cell. Cell Wall: complex, semiarid structure responsible for the shape of the cell, protects the interior of the cell from adverse changes in the outside environment. Endosperm: Specialized “resting” cells called endosperm. Metabolism: Bacteria exhibit an extremely wide variety of metabolic types. The distribution of metabolic traits within a group of bacteria has traditionally been used to define their taxonomy, but these traits often do not correspond with modern genetic classifications.

Bacterial metabolism is classified into nutritional groups on the basis to three major criteria: the kind to energy used tort growth, the source to carbon, and the electron donors used for growth. Another way of life of chemotherapy in the absence of possible electron acceptors is fermentation, wherein the electrons taken from the reduced substrates are transferred to oxidized intermediates to generate reduced fermentation products e. G. , lactate, ethanol, hydrogen, butyric acid).

Fermentation is possible, because the energy content of the substrates is higher than that of the products, which allows the organisms to synthesis TAP and drive their metabolism. These processes are also important in biological responses to pollution; for example, sulfate-reducing bacteria are largely responsible for the production of the highly toxic forms of mercury (methyl- and diametrically) in the environment. Non-respiratory anaerobes use fermentation to generate energy and reducing power, secreting metabolic by- products (such as ethanol in brewing) as waste.

Facultative anaerobes can switch between fermentation and different terminal electron acceptors depending on the environmental conditions in which they find themselves. Growth and Reproduction: Unlike in multicultural organisms, increases in cell size (cell growth and reproduction by cell division) are tightly linked in unicellular organisms. Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction. Under optimal conditions, bacteria can grow and divide extremely rapidly, and bacterial populations can double as quickly as every 9. Minutes. In cell division, two identical clone daughter cells are produced. Some bacteria, while still reproducing asexually, form more complex reproductive structures that help disperse the newly formed daughter cells. Examples include fruiting body formation by Mycobacterium and aerial hyper formation by Streptomycin, or budding. Budding involves a cell forming a protrusion that breaks away and produces a daughter cell. In the laboratory, bacteria are usually grown using solid or liquid media.

Solid growth media such as agar plates are used to isolate pure cultures of a bacterial strain. However, liquid growth media are used when measurement of growth or large lumen of cells are required. Growth in stirred liquid media occurs as an even cell suspension, making the cultures easy to divide and transfer, although isolating single bacteria from liquid media is difficult. The use of selective media (media with specific nutrients added or deficient, or with antibiotics added) can help identify specific organisms.

Most laboratory techniques for growing bacteria use high levels of nutrients to produce large amounts of cells cheaply and quickly. However, in natural environments, nutrients are limited, meaning that bacteria cannot continue to reproduce indefinitely. This nutrient limitation has led the evolution of different growth strategies (see r/K selection theory). Some organisms can grow extremely rapidly when nutrients become available, such as the formation of algal (and controversial) blooms that often occur in lakes during the summer.

Other organisms have adaptations to harsh environments, such as the production of multiple antibiotics by Streptomycin that inhibit the growth of competing microorganisms. In nature, many organisms live in communities (e. G. , films) that may allow for increased supply of nutrients and protection from environmental stresses. These relationships can be essential tort gar n to a particular organism or group of organisms (synchrony). Bacterial growth follows four phases. When a population of bacteria first enter a high-nutrient environment that allows growth, the cells need to adapt to their new environment.

The first phase of growth is the lag phase, a period of slow growth when the cells are adapting to the high-nutrient environment and preparing for fast growth. The lag phase has high biosynthesize rates, as proteins necessary for rapid growth are produced. The second phase of growth is the log phase, also known as the logarithmic or exponential phase. The log phase is marked by rapid exponential growth. The rate at which cells grow during this phase is known as the growth rate (k), and the time it takes the cells to double is known as the generation time (g).

During log phase, nutrients are metabolites at maximum speed until one of the nutrients is depleted and starts limiting growth. The third phase of growth is the stationary phase and is caused by depleted nutrients. The cells reduce their metabolic activity and consume non-essential cellular proteins. The stationary phase is a transition from rapid growth to a stress response state and here is increased expression of genes involved in DNA repair, antioxidant metabolism and nutrient transport. The final phase is the death phase where the bacteria runs out of nutrients and dies.

Genetics: Most bacteria have a single circular chromosome that can range in size from only 160,000 base pairs in the endometriosis bacteria Candidates Casseroles ruddier, to 12,200,000 base pairs in the soil-dwelling bacteria Geranium celluloses. Spirochetes of the genus Boreal are a notable exception to this arrangement, with bacteria such as Boreal buffering, the cause of Lime disease, containing a single linear chromosome. The genes in bacterial genomes are usually a single continuous stretch of DNA and although several different types of intros do exist in bacteria, these are much more rare than in eukaryote.

Bacteria may also contain plasmids, which are small extra-chromosomal Dana that may contain genes for antibiotic resistance or virulence factors. Bacteria, as asexual organisms, inherit identical copies of their parent’s genes (I. E. , they are clonally). However, all bacteria can evolve by selection on changes to their genetic material DNA caused by genetic recombination or mutations. Mutations come from errors made during the application of DNA or from exposure to mutagens. Mutation rates vary widely among different species of bacteria and even among different clones of a single species of bacteria.

Genetic changes in bacterial genomes come from either random mutation during replication or “stress-directed mutation”, where genes involved in a particular growth-limiting process have an increased mutation rate. Behavior: Secretion: Bacteria frequently secrete chemicals into their environment in order to modify it favorably. The secretions are often proteins and may act as enzymes that digest some form of food in the environment. Fluorescence: A few bacteria have chemical systems that generate light.

This fluorescence often occurs in bacteria that live in association with fish, and the light probably serves to attract fish or other large animals. Multicultural: Bacteria often function as multicultural aggregates known as films, exchanging a variety to molecular signals tort inter-cell communication, and engaging in coordinated multicultural behavior. The communal benefits of multicultural cooperation include a cellular division of labor, accessing resources that cannot effectively be utilized by single cells, collectively defending against antagonists, and optimizing population survival by differentiating into distinct cell types.

For example, bacteria in films can have more than 500 times increased resistance to antibacterial agents than individual “plankton” bacteria of the same species. Movement Many bacteria can move using a variety of mechanisms: flagella are used for swimming through fluids; bacterial gliding and twitching motility move bacteria across surfaces; and changes of buoyancy allow vertical motion. Swimming bacteria frequently move near 10 body lengths per second and a few as fast as 100. This sakes them at least as fast as fish, on a relative scale.

Interaction with Other Organisms: Despite their apparent simplicity, bacteria can form complex associations with other organisms. These symbiotic associations can be divided into parasitism, mutuality and commercialism. Due to their small size, commensally bacteria are ubiquitous and grow on animals and plants exactly as they will grow on any other surface. However, their growth can be increased by warmth and sweat, and large populations of these organisms in humans are the cause of body odor.

Predators Some species of bacteria kill and then consume other microorganisms, these species ladled predatory bacteria. These include organisms such as Mucosa’s acanthus, which forms swarms of cells that kill and digest any bacteria they encounter. Other bacterial predators either attach to their prey in order to digest them and absorb nutrients, such as Bioinformatics, or invade another cell and multiply inside the cytology, such as Deprecate.

These predatory bacteria are thought to have evolved from saprophytes that consumed dead microorganisms, through adaptations that allowed them to entrap and kill other organisms. Mutuality Certain bacteria form close spatial associations that are essential for their survival. One such naturalistic association, called interspecies hydrogen transfer, occurs between clusters of anaerobic bacteria that consume organic acids such as butyric acid or proportion acid and produce hydrogen, and anthropogenic Archie that consume hydrogen.

Only the intimate association with the hydrogen-consuming Archie keeps the hydrogen concentration low enough to allow the bacteria to grow. In soil, microorganisms that reside in the rhizomes (a zone that includes the root surface and the soil that adheres to the root after gentle shaking) carry out nitrogen fixation, converting nitrogen gas to nitrogenous compounds. This serves to provide an easily observable form of nitrogen for many plants, which cannot fix nitrogen themselves. Many other bacteria are found as symbiosis in humans and other organisms.

For example, the presence of over 1,000 bacterial species in the normal human gut flora of the intestines can contribute to gut immunity, synthesis vitamins such as folic acid, vitamin K and biotin, convert sugars to lactic acid (see Lasciviously), as well as fermenting complex indigestible carbohydrates. The presence of this gut flora also inhibits the growth of potentially pathogenic bacteria usually through competitive exclusion) and these beneficial bacteria are consequently sold as proportion dietary supplements Pathogens If bacteria form a parasitic association with other organisms, they are classed as pathogens.

Pathogenic bacteria are a major cause of human death and disease and cause infections such as tetanus, typhoid fever, diphtheria, syphilis, cholera, fodder illness, leprosy and tuberculosis. A pathogenic cause for a known medical disease may only be discovered many years after, as was the case with Helicopter pylori and peptic ulcer disease. Bacterial diseases are also important in agriculture, tit bacteria causing leaf spot, fire blight and wilts in plants, as well as John’s disease, mastitis, salmonella and anthrax in farm animals. Each species of pathogen has a characteristic spectrum of interactions with its human hosts.

Some organisms, such as Staphylococcus or Streptococcus, can cause skin infections, pneumonia, meningitis and even overwhelming sepsis, a systemic inflammatory response producing shock, massive vacillation and death. Yet these organisms are also part of the normal human flora and usually exist on the skin or in the nose without causing any disease at all. Other organisms invariably cause disease in humans, such as the Ricketiest, which are obligate intracellular parasites able to grow and reproduce only within the cells of other organisms.

One species of Ricketiest causes typhus, while another causes Rocky Mountain spotted fever. Chlamydia, another phylum of obligate intracellular parasites, contains species that can cause pneumonia, or urinary tract infection and may be involved in coronary heart disease. Finally, some species such as Pseudonymous organisms, Freeholder concordance, and Mycobacterium avian are opportunistic pathogens and cause disease mainly in people suffering from mispronunciation or cystic fibrosis.

Significance in technology and industry: Bacteria, often lactic acid bacteria such as Lasciviously and Lactose’s, in combination with yeasts and molds, have been used for thousands of years in the preparation of fermented foods such as cheese, pickles, soy sauce, sauerkraut, vinegar, wine and yogurt. The ability of bacteria to degrade a variety of organic compounds is remarkable and has been used in waste processing and premeditation. Bacteria capable of digesting the hydrocarbons in petroleum are often used to clean up oil spills.

Fertilizer was added to some of the beaches in Prince William Sound in an attempt to promote the growth of these naturally occurring bacteria after the 1989 Exxon Valued oil spill. These efforts were effective on beaches that were not too thickly covered in oil. Bacteria are also used for the premeditation of industrial toxic wastes. In the chemical industry, bacteria are most important in the production of anagrammatically pure chemicals for use as pharmaceuticals or agrochemicals. Bacteria can also be used in the place of pesticides in the biological pest control.

This commonly involves Bacillus hurriedness (also called SST), a Gram-positive, soil dwelling bacterium. Subspecies of this bacteria are used as a Lepidopterist-specific insecticides under trade names such as Dipped and Directed. Because of their specificity, these pesticides are regarded as environmentally friendly, with little or no effect on humans, wildlife, pollinators and most other beneficial insects. Because of their ability to quickly grow and the relative ease with which they can be manipulated, bacteria are the workhorses for the fields of molecular biology, genetics and biochemistry.

By making mutations in bacterial DNA and examining the resulting phenotypes, scientists can determine the function of genes, enzymes and metabolic pathways in bacteria, then apply this knowledge to more complex organisms. This aim of understanding the biochemistry of a cell reaches its most complex expression in the synthesis of huge amounts of enzyme kinetic and gene expression data into mathematical models of entire organisms. This is achievable in some well-studied bacteria, with models of Escherichia coli metabolism now being produced and tested.

This understanding of bacterial metabolism and genetics allows the use of biotechnology to bioengineering cetera for the production of therapeutic proteins, such as insulin, growth factors, or antibodies. THE PRACTITIONER: Which includes most of the gram-negative, chemotherapeutic bacteria, are presumed to have arisen from a common photosynthetic ancestor. They are now the largest taxonomic group of bacteria. The name Practitioner was taken from the mythological Greek god Protest, who could assume many shapes. Distinctive groups of Practitioner are designated by Greek letters.

The 0 (alpha) Practitioner: includes most of the practitioner that are capable of growth at very low level of nutrients. Some have unusual morphology, including protrusions such as stalks or buds known as prosthetic. The alpha practitioner also include agriculturally important bacteria capable of including nitrogen fixation in symbiosis with plants, and several plant and human pathogens. Spiritually: a soil bacterium that grows in close association with the roots of many plants, especially tropical grasses.

It uses nutrients excreted by plants and in return fixes nitrogen from the atmosphere. This form of nitrogen fixation is most significant in some tropical grasses and in sugar cane, although the organism can be isolated from the root system of many amperage-climate plants, such as corn. Extractor and Coelenterate: are industrially important aerobic organisms that convert ethanol into acetic vinegar. Ricketiest: obligate intracellular parasites-that is, they reproduce only within a mammalian cell. The ricketiest are gram-negative rod-shaped bacteria, or sociability.

They are transmitted to humans by bites of insects and ticks, as are the Collegial. They are also responsible for a number of diseases known as the spotted fever group. These include the epidemic typhus, caused by Ricketiest prioritize and transmitted by lice. Railhead: are gram negative, ricketiest like bacteria that live obligate within white blood cells. Railhead species are transmitted by ticks to humans and cause relationship, a sometimes fatal disease. Collaborate and Hyperthyroidism: are found in low nutrient aquatic environments, such as lakes.

They feature stalks that anchor the organs to surfaces. This arrangement increases their nutrient uptake because they are exposed to a continuously changing flow of water and because the stalk increases the surface to volume ratio of the cell. Rhizome and Crematorium: includes agriculturally important bacteria that pacifically infect the roots of leguminous plants, such as beans, peas, or clover. The presence of bacteria leads to formation of nodules in which the bacteria and plant tort a symbiotic relationship, resulting in the fixation to nitrogen trot the air tort use by the plant.

Pardonable: contains several members that are human pathogens. The best known is Pardonable Hansel, a gram-negative bacillus that causes cat-scratch disease. Barnacle: small nonmetal sociability. All species of Barnacle are obligate parasites of mammals and cause the disease brucellosis. Of medical interest is the ability of Barnacle to survive phagocytes, an important element of the body defense against bacteria. Interacted and Interactions: genera of notifying bacteria that are great importance to the environment and to agriculture.

They are chemotherapy’s capable of using inorganic chemicals as energy sources and carbon dioxide as the only source of carbon, from which they synthesize all of their complex chemical make-up. Wallach’s: most common infectious bacterial genus in the world. They live only inside the cells of their hosts, usually insects. Therefore, Albania escape detection by the use of usual culture methods. The 0 (beta) Practitioner: use nutrient substances that diffuse away from areas of anaerobic decomposition of organic matter, such as hydrogen gas, ammonia, and methane. Several important pathogenic bacteria are found on this group.

Tabulations: sulfur-oxidation bacteria are important in the sulfur cycle. These chemotherapeutic bacteria are capable of obtaining energy by oxidation the reduced forms of sulfur, such as hydrogen sulfide, or elemental sulfur, into sulfates. Spiritual: the habitat of genus Spiritual is mainly fresh water. An important rapscallion difference from the helical spirochetes is that Spiritual bacteria are motile by conventional polar flagella, rather than axial filaments. Exasperations: sheathed bacteria, which include Exasperations ants, are found in freshwater and in sewage.

Exasperations probably contributes to bulking, an important problem in sewage treatment. Freeholder: motile by a single polar flagellum or tuft of flagella. The best known species is the aerobic, gram negative rod Freeholder icepack. It has an extraordinary nutritional spectrum and is capable of degrading more than 100 different organic molecules. This capability is often a factor in contamination of equipment and drugs in the hospitals, these bacteria may eventually grow in disinfectant solutions. Bordello: the nonmetal, aerobic gram negative rod Bordello pressures.

This serious pathogen is the cause of pressures, or whooping cough. Engineers: aerobic, gram-negative Cisco that usually inhabit the mucous membrane of the mammals. Pathogenic species include concusses bacterium Engineers generator, the causative agent for generator. Google: important in the context of aerobic sewage-treatment processes, such as the activated sludge system. As they grow, Google bacteria form fluffy, slimy masses that are essential to the operation of such systems. The 0 (gamma) Practitioner: constitute the largest subgroup of the practitioner and include a great variety of physiological types.

Begonia: grows in aquatic sediments at the interface between anaerobic and aerobic layers. Morphologically, it resembles filamentous contractible, but is not photosynthetic. Motility is by gliding. Franciscans: genus of small polymorphic bacteria that grow only on complex media enriched with blood or tissue extracts. Pseudonymous: gram-negative aerobic odds or Cisco. The most important genus in this group is the Pseudonymous. Pseudonyms: consists to aerobic, gram negative rods that are motile by polar telltale, either single or tufts. They are very common in soil and other natural environments.

Extractor and Samoan: free living in soil, large, ovoid, heavily capitulated bacteria are frequently used in laboratory demonstrations of nitrogen fixation. They would require energy sources such as carbohydrates, that are in limited supply in the soil. Marmoreal: strictly aerobic sociability that is, intermediate in shape between Cisco and rods. Marmoreal lacuna is implicated in conjunctivitis, an inflammation in conjunctiva, the membrane that covers the eye and lines the eyelids. Legionary: originally isolated during a search for the cause of an outbreak of pneumonia now known as legislation.

The search was difficult because these bacteria did not go on usual laboratory isolation media then available. Collegial: requires a mammalian host cell in order to reproduce. They are not transmitted among humans by insect or tick bites. Brainless: facultative anaerobic gram negative rods. Many are slightly curved. They are found mostly in aquatic habitats. Brio: rods that are often slightly curved. One important pathogen is the Brio cholera, the causative agent of cholera. The disease is characterized by a profuse and watery diarrhea.

Intolerableness: facultative anaerobic, gram negative rods that are, if motile, perspicuously flagellated. They have simple nutritional requirements. This is an important bacterial group, often commonly called enteric. This reflects the fact that they inhabit the intestinal tracts of humans and other animals. Most enteric are active ferments of glucose and other carbohydrates. Escherichia: the bacterial species Escherichia Coli s one of the most common inhabitants of the human intestinal tract and is probably the most familiar organism in microbiology.

Its presence in water or food is an indication of fecal contamination. E. Coli is not usually pathogenic. However, it can be a cause of urinary tract infections, and certain strains produce interventions. Salmonella: potentially pathogenic. Common inhabitants of intestinal tracts of many animals, especially poultry and cattle. Under unsanitary conditions, they can contaminate food. Shillelagh: responsible for a disease called dysentery, or shillelaghs. Unlike salmonella, they are found only in humans. Kielbasa: commonly found in soil or water.

The species Kielbasa pneumonia occasionally causes a serious form of pneumonia in human. Seriate: Seriate mercenaries a bacterial species distinguished by its production of red pigment. In hospital situations the organism can be found on catheters, in saline irrigation solutions, and in other supposedly sterile solutions. Protest: bacteria growing on agar exhibit a swimming type of growth. Swarmed cells with many flagella and reduced motility. This genus of bacteria is implicated in many infections of the urinary tract and in wounds. Yearnings: Yearnings Estes causes plague, the Black Death of medieval Europe.

Urban rats in some parts of the world and ground squirrels in the American Southwest carry these bacteria. Fleas usually transmit the organisms among animals and to humans. Erwin: primarily plant pathogens; some cause plant soft-rot diseases. These species produce enzymes that hydrology the pectin between individual plant cells. This causes the plant cells to separate from each other, a disease that plant pathologists term plant rot. Interrogator: E. Cloacae and E. Arrogance can cause urinary tract infections and hospital acquired infections.

They are widely distributed in humans and animals, as well as water, sewage and soil. Pastureland: nonmetal; best known as human and animal pathogens. Pastured: pathogen to domestic animals. It causes sepsis in castles, fowl cholera in chickens. The best known species is Pastured multimedia, which can be transmitted to humans by dog and cat bites. Hemophilia: commonly inhabit the mucous membrane of the upper respiratory tract, mouth, vagina and the intestinal tract. The best known species that affects humans is Hemophilia influenza, named long ago because of the erroneous belief hat it was responsible for influenza.

The 0 (delta) practitioner: they include some bacteria that are predators on other bacteria. Bacteria in this group are also important contributors to the sulfur cycle. Bowdlerize: it attacks other gram negative bacteria. It attaches tightly, and after penetrating the outer layer of gram negative bacteria, it reproduces within the peripheral. Desultoriness: obligate anaerobic bacteria that use oxidized forms of sulfur, such as sulfates, or elemental sulfur. The product of this reduction is hydrogen sulfide. Desultoriness: the best studied sulfur reducing genus.

Which is found in anaerobic sediments, and also in intestinal tracts of humans and animals. Macromolecules: fruiting and gliding bacteria. Most complex life cycle of all bacteria, part of which is predatory upon other bacteria. Mucosa’s: vegetative cells of the mycobacterium move by gliding and leave behind slime trail. The 0 (epsilon) Practitioner: slender gram negative rods that are helical or fibroid. Fibroid is a term applied to helical bacteria that do not have a complete turn. Comparable: microelectronic fibrils; each cell has one polar flagellum.

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