discovery of microorganisms

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Information about discovery of microorganisms

Published on April 7, 2013

Author: nishikaa


DISCOVERY OF MICROORGANISMS : DISCOVERY OF MICROORGANISMS PRESENTATION BY: NISHIKA BHAN Sub-Topics: Sub-Topics Early discovery of pathogenic microorganisms. Development of bacteriology as a scientific discipline. Contributions made by eminent scientists. Evolution of the microbes : Evolution of the microbes Single-celled microorganisms were the first forms of life to develop on Earth, approximately 3–4 billion years ago. Further evolution was slow, and for about 3 billion years all organisms were microscopic. So, for most of the history of life on Earth the only forms of life were microorganisms. Pre-microbiology : Pre-microbiology The possibility that microorganisms exist was discussed for many centuries before their actual discovery in the 17th century. The existence of unseen microbiological life was postulated by Jainism which is based on Mahavira’s teachings as early as 6th century BCE. Paul Dundas noted that Mahavira asserted existence of unseen microbiological creatures living in earth, water, air and fire. However, the earliest known idea to indicate the possibility of diseases spreading by yet unseen organisms was that of the Roman scholar Marcus Varro in a 1st century BC book titled On Agriculture in which he warns against locating a homestead near swamps. contd.: contd. When Black Death bubonic plague reached Spain, in the 14th century, Ibn Khatima wrote that infectious diseases were caused by contagious "minute bodies" that enter the human body. Later, in 1546, Girolamo Fracastoro proposed that epidemic diseases were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or even without contact over long distances. PowerPoint Presentation: All these early claims about the existence of microorganisms were speculative and were not based on any data or science. Microorganisms were neither proven, observed, nor correctly and accurately described until the 17th century. The reason for this was that all these early studies lacked the microscope. History of microorganisms' discovery : History of microorganisms' discovery Anton van Leeuwenhoek was the first to observe microorganisms in 1675, using a microscope of his own design, and made one of the most important contributions to biology. Robert Hooke was the first to use a microscope to observe living things; his 1665 book Micrographia contained descriptions of plant cells. Contd.: Contd. Before Leeuwenhoek's discovery of microorganisms, it had been a mystery why grapes could be turned into wine, milk into cheese, or why food would spoil. Leeuwenhoek did not make the connection between these processes and microorganisms, but using a microscope, he did establish that there were forms of life that were not visible to the naked eye. Leeuwenhoek's discovery, along with subsequent observations by Lazzaro Spallanzani and Louis Pasteur, ended the long-held belief that life spontaneously appears from non-living substances. contd.: contd. In 1876, Robert Koch established that microbes can cause disease. He found that the blood of cattle who 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 microbe and a disease and these are now known as Koch's postulates. Robert Koch (1843–1910) examining a specimen in his laboratory.: Robert Koch (1843–1910) examining a specimen in his laboratory. The Role of Microorganisms in Disease: The Role of Microorganisms in Disease The importance of microorganisms in disease was not immediately obvious to people, and it took many years for scientists to establish the connection between microorganisms and illness. Recognition of the role of microorganisms depended greatly upon the development of new techniques for their study. Once it became clear that disease could be caused by microbial infections, microbiologists began to examine the way in which hosts defended themselves against microorganisms and to ask how disease might be prevented. This led to the development of immunology. Recognition of the Relationship between Microorganisms and Disease: Recognition of the Relationship between Microorganisms and Disease Although Fracastoro and a few others had suggested that invisible organisms produced disease, most believed that disease was due to causes such as supernatural forces and poisonous vapours. Discovery of pathogenic microorganisms: Discovery of pathogenic microorganisms Agostino Bassi (1773–1856) first showed that a microorganism could cause disease when he demonstrated in 1835 that a silkworm disease was due to a fungal infection. He also suggested that many diseases were due to microbial infections. In 1845 M. J. Berkeley proved that the great Potato Blight of Ireland was caused by a fungus. Contd.: Contd. Indirect evidence that microorganisms were agents of human disease came from the work of the English surgeon Joseph Lister (1827–1912) on the prevention of wound infections. Lister impressed with Pasteur’s studies on the involvement of microorganisms in fermentation, developed a system of antiseptic surgery designed to prevent microorganisms from entering wounds. Instruments were heat sterilized, and phenol was used on surgical dressings and at times sprayed over the surgical area. The approach was remarkably successful and transformed surgery. It also provided strong indirect evidence for the role of microorganisms in disease because phenol, which killed bacteria, also prevented wound infections. PowerPoint Presentation: The first direct demonstration of the role of bacteria in causing disease came from the study of anthrax by the German physician Robert Koch (1843–1910). He devised a criteria for establishing a causal link between a microbe and a disease and these are known as Koch's postulates. Koch's postulates: Koch's postulates Koch's postulates are four criteria designed to establish a causal relationship between a causative microbe and a disease. Formulated by Robert Koch and Friedrich Loeffler in 1884. Refined and published by Koch in 1890. Koch applied the postulates to establish the etiology of anthrax and tuberculosis, but they have been generalized to other diseases also. Koch's postulates : Koch's postulates The microorganism must be present in every case of the disease but absent from healthy organisms. The suspected microorganism must be isolated and grown in a pure culture. The same disease must result when the isolated microorganism is inoculated into a healthy host. The same microorganism must be isolated again from the diseased host. Development of Bacteriology as a Scientific Discipline: Development of Bacteriology as a Scientific Discipline History of bacteriology : History of bacteriology Bacteria were first observed by Antonie van Leeuwenhoek in 1676, using a single-lens microscope of his own design. He called them "animalcules" and published his observations in a series of letters to the Royal Society. The name bacterium was introduced much later, by Christian Gottfried Ehrenberg in 1838. Louis Pasteur demonstrated in 1859 that the fermentation process is caused by the growth of microorganisms. Development of Bacteriology: Development of Bacteriology Schwann published a paper and then moved on to other research; twenty years later Louis Pasteur extended Schwann's work to other fermentations and to disease, publishing hundreds of papers and numerous books, training students and gathering associates into his laboratory and thus establishing a school of research on microscopic organisms. Second phase in the emergence of bacteriology: Second phase in the emergence of bacteriology The phase 1875–1890 is associated especially with Robert Koch. The methods and instruments of chemistry were supplemented and often replaced by novel ways of cultivating and representing microorganisms. The delicate blown-glass globe was taken from chemistry by Schwann and Pasteur for use in growing microbial cultures which was tricky to manage and precarious to transport. This became the simple, transportable glass dish known as Petri Dish, named after Koch's associate Richard Petri , now ubiquitous in biomedicine. Whereas Pasteur's difficult methods had been adopted by a mere handful of investigators outside his laboratory, now the new bacteriological technique has spread throughout the world. Emergence of Bacteriology: Emergence of Bacteriology In 1880 Pasteur's invention of artificial vaccines launched the study of immunity and immunization. But it also made bacteriology something it had not been before, namely, experimental biology (includes experimental study of species, inheritance and variation). In the 20 th century, the study of microbial variation and of the associated phenomenon of infection of bacteria by virus (bacteriophage) came to have momentous theoretical consequences for the life sciences through its central role in the origin of molecular biology and genetics. PowerPoint Presentation: From its earliest, dramatic achievements, bacteriology was an icon of the triumph of technical skill and experimental discipline over speculation and superstition. Yet as some bacteriologists themselves pointed out, bacteriological research has also been shaped by myths and beliefs concerning purity and danger, life and death: disease-causing germs as demons or enemies. The scope of meanings of microbiological research has continued ever since to range from the mundane (the quality of beer and the safety of milk) to the cosmic (the origin of life and the cycle of matter) to the political and social (relative importance of “seed” and “soil,” or germs and social conditions, in disease causation). PowerPoint Presentation: Alongside these wider meanings, the rise of bacteriology involved a conceptual transformation in medicine : from defining diseases by their circumstances, symptoms, and pathologies to defining them by their causes; from clinical and pathological to etiological definitions of disease. Bacteriology gave medicine and hygiene powerful reasons for focusing on the identification and control of specific causes. PowerPoint Presentation: With its array of products and services, bacteriology ushered in an era in the history of science in which experiment is often synonymous with invention. The intimate and constant interaction of Pasteur, Koch, Paul Ehrlich, and others with government and business became a compelling model for the organization of scientific life in the twentieth century. The establishment of the Pasteur Institute in Paris (1888), Koch's institute in Berlin (1891), the Lister Institute in London (1891), Ehrlich's institute in Frankfurt (1899), and the Rockefeller Institute in New York (1901) inaugurated a new kind of large, national, nonuniversity research institutions and an expansion in the scale and social role of the sciences of health and life, their growth into an omnipresent complex involving industry, commerce, the state, and the consumer. Contributions Made By Eminent Scientists: Contributions Made By Eminent Scientists PowerPoint Presentation: 1546 : Fracastoro suggests that invisible organisms cause disease. 1590–1608: Jansen develops first useful compound microscope. 1676 : Leeuwenhoek discovers “animalcules”. 1688 : Redi publishes work on spontaneous generation of maggots. PowerPoint Presentation: 1786 : Müller produces first classification of bacteria. 1798 : Jenner introduces cowpox vaccination for smallpox. 1838–1839 : Schwann and Schleiden, the Cell Theory. 1835–1844 : Bassi discovers that silkworm disease is caused by a fungus and proposes that many diseases are microbial in origin. 1857 : Pasteur shows that lactic acid fermentation is due to a microorganism. 1858 : Virchow states that all cells come from cells. 1861 : Pasteur shows that microorganisms do not arise by spontaneous generation. 1867 : Lister publishes his work on antiseptic surgery. PowerPoint Presentation: 1876–1877 : Koch demonstrates that anthrax is caused by Bacillus anthracis. 1880 : Laveran discovers Plasmodium, the cause of malaria. 1881 : Koch cultures bacteria on gelatin and Pasteur develops anthrax vaccine. 1882 : Koch discovers tubercle bacillus, Mycobacterium tuberculosis. 1884 : Koch’s postulates first published, Metchnikoff describes phagocytosis, Autoclave developed, and Gram stain developed. 1885 : Pasteur develops rabies vaccine, Escherich discovers Escherichia coli, a cause of diarrhea. 1886 : Fraenkel discovers Streptococcus pneumoniae, a cause of pneumonia. PowerPoint Presentation: 1896 : Van Ermengem discovers Clostridium botulinum, the cause of botulism. 1897 : Buchner prepares extract of yeast that ferments, Ross shows that malaria parasite is carried by the mosquito. 1899 : Beijerinck proves that a virus particle causes the tobacco mosaic disease. 1928 : Griffith discovers bacterial transformation. 1929 : Fleming discovers penicillin. 1944 : Waksman discovers streptomycin. 1946 : Lederberg and Tatum describe bacterial conjugation. 1977 : Recognition of archaea as a distinct microbial group by Woese and Fox. References : References Prescott L.M.,2002. Microbiology. Brock, T. D. 1988. Robert Koch: A life in medicine and bacteriology. Dobell, C. 1960. Antony van Leeuwenhoek and his “little animals.” History_of_bacteriology THANK-YOU: THANK-YOU

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