Microorganism - Wikipedia, the free encyclopedia. A microorganism (from the Greek: ОјО№ОєПЃПЊП‚, mikros, "small" and бЅЂПЃОіО±ОЅО№ПѓОјПЊП‚, organism. Гіs, "organism") is a microscopiclivingorganism, which may be single celled[1] or multicellular. The study of microorganisms is called microbiology, a subject that began with the discovery of microorganisms in 1. A microorganism (from the Greek: μικρός, mikros, 'small' and ὀργανισμός, organismós, 'organism') is a microscopic living organism, which may be single celled [1] or multicellular. The study of microorganisms. Abstract. The synthesis, crystal structure and solid state properties of three different groups of magnetic organic–inorganic hybrid compounds are described and discussed. The reported examples are crystalline solids built. Comandanti; Capo di Stato Maggiore (CSM) Generale Dalbir Singh Suhag: Vice Capo di Stato Maggiore (VCSM) Tn. Gen. MMS Rai: Comandanti degni di nota: Feldmaresciallo K.M. Cariappa Feldmaresciallo Sam Manekshaw Generale K.S. Antonie van Leeuwenhoek, using a microscope of his own design. Microorganisms are very diverse and include all bacterial, archaean and most of the protozoan species on the planet. This group also contains some species of fungi, algae, and certain animals, such as rotifers. Data Structure By R S Salaria Pdf995The Milliarium Aureum (Classical Latin: [miːllɪˈaːrɪʊm ˈawrɛʊm], golden milestone) was a monument, probably of marble or gilded bronze, erected by the Emperor Caesar Augustus near the Temple of Saturn in the central. 99 12. Data Structure through C by Yashwant Kanekar, BPB Publications 13. Data Structure through C in depth by SK Srivastava, Deepali Srivastava, BPB Publications 14. Introduction to Data Structure and Algorithm with C++ by. Many macroscopic animals and plants have microscopic juvenile stages. Some microbiologists also classify viruses (and viroids) as microorganisms, but others consider these as nonliving.[2][3]Microorganisms live in every part of the biosphere, including soil, hot springs, "seven miles deep" in the ocean, "4. Earth's crust (see also endolith).[4] Microorganisms, under certain test conditions, have been observed to thrive in the vacuum of outer space.[5][6] The total amount of soil and subsurface bacterial carbon is estimated as 5 x 1. United Kingdom".[4] The mass of prokaryote microorganisms — which includes bacteria and archaea, but not the nucleated eukaryote microorganisms — may be as much as 0. On 1. 7 March 2. 01. Mariana Trench. the deepest spot in the Earth's oceans.[8][9] Other researchers reported related studies that microorganisms thrive inside rocks up to 5. United States,[8][1. Japan.[1. 1] On 2. August 2. 01. 4, scientists confirmed the existence of microorganisms living 8. Antarctica.[1. 2][1. According to one researcher, "You can find microbes everywhere — they're extremely adaptable to conditions, and survive wherever they are."[8]Microorganisms are crucial to nutrient recycling in ecosystems as they act as decomposers. As some microorganisms can fix nitrogen, they are a vital part of the nitrogen cycle, and recent studies indicate that airborne microorganisms may play a role in precipitation and weather.[1. Microorganisms are also exploited in biotechnology, both in traditional food and beverage preparation, and in modern technologies based on genetic engineering. A small proportion of microorganisms are pathogenic and cause disease and even death in plants and animals.[1. Microorganisms are often referred to as microbes, but this is usually used in reference to pathogens. Evolution[edit]Single- celled microorganisms were the first forms of life to develop on Earth, approximately 3–4 billion years ago.[1. Further evolution was slow,[1. Precambrianeon, all organisms were microscopic.[2. So, for most of the history of life on Earth, the only forms of life were microorganisms.[2. Bacteria, algae and fungi have been identified in amber that is 2. Triassic period.[2. The newly discovered biological role played by nickel, however — especially that engendered by volcanic eruptions from the Siberian Traps (site of the modern city of Norilsk) — is thought to have accelerated the evolution of methanogens towards the end of the Permian–Triassic extinction event.[2. Microorganisms tend to have a relatively fast rate of evolution. Most microorganisms can reproduce rapidly, and bacteria are also able to freely exchange genes through conjugation, transformation and transduction, even between widely divergent species.[2. This horizontal gene transfer, coupled with a high mutation rate and many other means of genetic variation, allows microorganisms to swiftly evolve (via natural selection) to survive in new environments and respond to environmental stresses. This rapid evolution is important in medicine, as it has led to the recent development of "super- bugs", pathogenicbacteria that are resistant to modern antibiotics.[2. Pre- microbiology[edit]The possibility that microorganisms exist was discussed for many centuries before their discovery in the 1. The existence of unseen microbiological life was postulated by Jainism, which is based on Mahavira's teachings as early as 6th century BCE.[2. Paul Dundas notes that Mahavira asserted the existence of unseen microbiological creatures living in earth, water, air and fire.[2. The Jain scriptures also describe nigodas, which are sub- microscopic creatures living in large clusters and having a very short life, which are said to pervade every part of the universe, even the tissues of plants and animals.[2. The earliest known idea to indicate the possibility of diseases spreading by yet unseen organisms was that of the Roman scholar Marcus Terentius Varro in a 1st- century BC book titled On Agriculture in which he warns against locating a homestead near swamps: … and because there are bred certain minute creatures that cannot be seen by the eyes, which float in the air and enter the body through the mouth and nose and they cause serious diseases.[2. In The Canon of Medicine (1. Ab. Е« Al. Д« ibn SД«n. ДЃ (Avicenna) hypothesized that tuberculosis and other diseases might be contagious.[3. In 1. 54. 6, Girolamo Fracastoro proposed that epidemicdiseases were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or even without contact over long distances. All these early claims about the existence of microorganisms were speculative and while grounded on indirect observations, they were not based on direct observation of microorganisms or systematized empirical investigation, e. Microorganisms were neither proven, observed, nor accurately described until the 1. The reason for this was that all these early studies lacked the microscope. History of microorganisms' discovery[edit]Louis Pasteur showed that Spallanzani's findings held even if air could enter through a filter that kept particles out. Antonie Van Leeuwenhoek (1. Robert Hooke, a contemporary of Leeuwenhoek, also used microscopes to observe microbial life; his 1. Micrographia describes these observations and coined the term cell. Before Leeuwenhoek's discovery of microorganisms in 1. Leeuwenhoek did not make the connection between these processes and microorganisms, but using a microscope, he did establish that there were signs of life that were not visible to the naked eye.[3. Leeuwenhoek's discovery, along with subsequent observations by Spallanzani and Pasteur, ended the long- held belief that life spontaneously appeared from non- living substances during the process of spoilage. Lazzaro Spallanzani (1. He also found that new microorganisms could only settle in a broth if the broth was exposed to air. Louis Pasteur (1. Spallanzani's findings by exposing boiled broths to the air, in vessels that contained a filter to prevent all particles from passing through to the growth medium, and also in vessels with no filter at all, with air being admitted via a curved tube that would not allow dust particles to come in contact with the broth. By boiling the broth beforehand, Pasteur ensured that no microorganisms survived within the broths at the beginning of his experiment. Nothing grew in the broths in the course of Pasteur's experiment. This meant that the living organisms that grew in such broths came from outside, as spores on dust, rather than spontaneously generated within the broth. Thus, Pasteur dealt the death blow to the theory of spontaneous generation and supported germ theory. In 1. 87. 6, Robert Koch (1. He found that the blood of cattle which were infected with anthrax always had large numbers of Bacillus anthracis. Koch found that he could transmit anthrax from one animal to another by taking a small sample of blood from the infected animal and injecting it into a healthy one, and this caused the healthy animal to become sick. He also found that he could grow the bacteria in a nutrient broth, then inject it into a healthy animal, and cause illness. Based on these experiments, he devised criteria for establishing a causal link between a microorganism and a disease and these are now known as Koch's postulates.[3. Although these postulates cannot be applied in all cases, they do retain historical importance to the development of scientific thought and are still being used today.[3. On 8 November 2. 01. Earth—the oldest complete fossils of a microbial mat (associated with sandstone in Western Australia) estimated to be 3. Classification and structure[edit]Microorganisms can be found almost anywhere in the taxonomic organization of life on the planet. Bacteria and archaea are almost always microscopic, while a number of eukaryotes are also microscopic, including most protists, some fungi, as well as some animals and plants. Viruses are generally regarded as not living and therefore not considered as microorganisms, although the field of microbiology also encompasses the study of viruses. Prokaryotes[edit]Prokaryotes are organisms that lack a cell nucleus and the other membrane bound organelles. They are almost always unicellular, although some species such as myxobacteria can aggregate into complex structures as part of their life cycle. Consisting of two domains, bacteria and archaea, the prokaryotes are the most diverse and abundant group of organisms on Earth and inhabit practically all environments where the temperature is below +1. В°C. They are found in water, soil, air, animals' gastrointestinal tracts, hot springs and even deep beneath the Earth's crust in rocks.[4. Practically all surfaces that have not been specially sterilized are covered by prokaryotes. The number of prokaryotes on Earth is estimated to be around five million trillion trillion, or 5 Г— 1. Earth.[4. 1]Bacteria[edit]Almost all bacteria are invisible to the naked eye, with a few extremely rare exceptions, such as Thiomargarita namibiensis.[4. They lack a nucleus and other membrane- bound organelles, and can function and reproduce as individual cells, but often aggregate in multicellular colonies.[4. Their genome is usually a single loop of DNA, although they can also harbor small pieces of DNA called plasmids. How should salinity influence fish growth? Development and growth (continuous in fish) are controlled by ‘internal factors’ including CNS, endocrinological and neuroendocrinological systems. Among vertebrates, they also are highly dependent on environmental conditions. Among other factors, many studies have reported an influence of water salinity on fish development and growth. In most species, egg fertilization and incubation, yolk sac resorption, early embryogenesis, swimbladder inflation, larval growth are dependent on salinity. In larger fish, salinity is also a key factor in controlling growth. Do the changes in growth rate, that depend on salinity, result from an action on: (1) standard metabolic rate; (2) food intake; (3) food conversion; and/or (4) hormonal stimulation? Better growth at intermediate salinities (8–2. Numerous studies have shown that 2. However, recent ones indicate that the osmotic cost is not as high (roughly 1. Data are also available in terms of food intake and stimulation of food conversion, which are both dependent on the environmental salinity. Temperature and salinity have complex interactions. Many hormones are known to be active in both osmoregulation and growth regulation, e. All of these factors are reviewed. As often, multiple causality is likely to be at work and the interactive effects of salinity on physiology and behaviour must also be taken into account. Copyright © 2. 00. Elsevier Science Inc. All rights reserved.
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