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Transcript
Micro – Chapter One Scope & History of Microbiology . . . my work, which I've done for a long time, was not pursued in order to gain the praise I now enjoy, but chiefly from a craving after knowledge, which I notice resides in me more than in most other men. And therewithal, whenever I found out anything remarkable, I have thought it my duty to put down my discovery on paper, so that all ingenious people might be informed thereof. Antony van Leeuwenhoek. Letter of June 12, 1716 Explain why the study of microbiology is important. Microorganisms have always been and will continue to be a major influence in our lives. Because of their relationship to our health and welfare, it is essential that we understand their characteristics. By studying their features we can also gain insight into the processes and relationships of all life forms. Outline the scope of microbiology. The study of microbes, but it is not just the study of bacteria… It also includes the study of viruses, algae, protists, fungi, and even the helminths (intestinal parasites). Also included are a great variety of diverse fields such as immunology and genetics that indirectly or directly relate to these microbes. There is tremendous diversity in this field of science. Detail some of the major events in the early history of microbiology. The Greeks, Romans, and Jews all contributed to early understandings of the spread of disease. Diseases such as bubonic plague, smallpox, and syphilis caused millions of deaths because of the lack of understanding of how to control or treat the infections. Also, the making of beer, bread, wine, and cheese are ancient practices which all rely on the actions of microorganisms (yeasts). Plague buboe Smallpox Syphilis (secondary) a.k.a. “Large Pox” The development of high– quality lenses (it was his hobby!) by Leeuwenhoek (even though his was not the first microscope) made it possible to observe microorganisms and later to formulate the cell theory. Cephalodella Video No. 1 About 200 species belong to this genus. They are found in many habitats including soft sandy substrates called psammon. They are fast swimmers with a typical turning movement. Some are raptorial. The shape of the toes, their proportion to body length, and the type of trophi (chitinous jaws) are important characteristics for identifying individual species. These bell-shaped ciliates live in fresh or salt water attached by a slender stalk to aquatic plants, surface scum, submerged objects, or aquatic animals. The stalk contains a contractile fibril called a myoneme that causes it to coil like a spring when stimulated. Vorticella eat bacteria and small protozoans, using their cilia to sweep their prey into mouth-like openings. Vorticella Video No. 1 explain the germ theory of disease and outline the historical developments that led to its formulation. The germ theory of disease states that microorganisms (germs) can invade other organisms and cause disease. Idea of spontaneous generation (that living things arise out of nonliving materials, with the help of a “life force” in the air) had to first be disproved. Enter in the clever studies of Redi and Spallanzani… Redi showed that flies must touch the meat (Redi had did not see the eggs, but he presumed they were there) to make maggots, and Spallanzani boiled gravy and sealed the flasks while they were boiling to show that when they cooled no animalcules would ever appear. There were still doubters, so now enter in Pasteur and his swan necked flasks…boil the liquid to kill everything, and yet air can still get in, and still no life forms. Ha! Koch's postulates: • the causative agent must be present in every case of the disease and must not be present in healthy animals. • the pathogen must be isolated from the diseased host animal and must be grown in pure culture. • the same disease must be produced when microbes from the pure culture are inoculated into healthy susceptible animals. • the same pathogen must be recoverable once again from this artificially infected animal and it must be able to be grown in pure culture. Koch's postulates not only proved the germ theory but also gave a tremendous boost to the development of microbiology by stressing a laboratory culture and identification of microorganisms. E.Coli Legionaires Disease staphylococcus Aseptic Technique-The handling of objects so as to maintain sterility. Joseph Lister made the link between lack of cleanliness in hospitals and deaths after operations, starting in the late 1860’s. For this reason, he is known as the ‘Father of Antiseptic Surgery’. Lister believed that it was microbes carried in the air that caused diseases to be spread in wards. highlight the events that marked the emergence of immunology, virology, chemotherapy, genetics, and molecular biology as branches of microbiology. -Immunology: smallpox vaccine by Jenner -Virology: discovery of pathogenic, filterable agents by Beijerinck & Iwanowski -Chemotherapy (using chemical substances to treat or cure diseases): pioneered by Ehrlich and Fleming with the discovery of sulfa drugs and antibiotics -Genetics and Molecular Biology: Griffith’s discovery of transformation and Avery who demonstrated that this genetic change was due to DNA Edward Jenner was a country doctor who had studied nature and his natural surroundings since childhood. He had always been fascinated by the rural old wives tale that milkmaids could not get smallpox. He believed that there was a connection between the fact that milkmaids only got a weak version of smallpox – the non-life threatening cowpox – but did not get smallpox itself. A milkmaid who caught cowpox got blisters on her hands and Jenner concluded that it must be the pus in the blisters that somehow protected the milkmaids. Jenner decided to try out a theory he had developed. A young boy called James Phipps would be his guinea pig. He took some pus from cowpox blisters found on the hand of a milkmaid called Sarah. She had milked a cow called Blossom and had developed the tell-tale blisters. Jenner ‘injected’ some of the pus into James. This process he repeated over a number of days gradually increasing the amount of pus he put into the boy. He then deliberately injected Phipps with smallpox. James became ill but after a few days made a full recovery with no side effects. It seemed that Jenner had made a brilliant discovery. He then encountered the prejudices and conservatism of the medical world that dominated London. They could not accept that a country doctor had made such an important discovery and Jenner was publicly humiliated when he brought his findings to London. However, what he had discovered could not be denied and eventually his discovery had to be accepted – a discovery that was to change the world. So successful was Jenner's discovery, that in 1840 the government of the day banned any other treatment for smallpox other than Jenner's. Jenner did not patent his discovery as it would have made the vaccination more expensive and out of the reach of many. It was his gift to the world. CREDIT:http://www.historylearningsite.co.uk/edward_jenner.htm On 12th February 1892, Dmitri Iwanowski, a Russian botanist, presented a paper to the St. Petersburg Academy of Science which showed that extracts from diseased tobacco plants could transmit disease to other plants after passage through ceramic filters fine enough to retain the smallest known bacteria. This is generally recognized as the beginning of Virology. Unfortunately, Iwanowski did not fully realize the significance of these results. (from: http://www.microbiologybytes.com/introduction/introduction.html) A few years later, in 1898, Martinus Beijerinick confirmed & extended Iwanowski's results on tobacco mosaic virus & was the first to develop the modern idea of the virus, which he referred to as contagium vivum fluidum ('soluble living germ'). (CREDIT: http://www.microbiologybytes.com/introduction/introduction.html) The "magic bullet" concept comes from the experience of 19th century German chemists with selectively staining tissues for histological examination, and in particular, selectively staining bacteria. In the late 1890’s Paul Ehrlich reasoned that if a compound could be made that selectively targeted a disease causing organism, then a toxin for that organism could be delivered along with the agent of selectivity. Hence, a "magic bullet" would be created that killed only the organism targeted. CREDIT: http://en.wikipedia.org/wiki/Paul_Ehrlich Alexander Fleming’s observations in 1928 that a neglected colony of Staphylococcus bacteria had been invaded by a fungus that seemed to kill the bacteria led to the isolation and purification of what we now know as Penicillin. German scientists were making synthetic antibiotics (sulfa drugs) in the late 1930’s, but they didn’t work on all bacterial infections (nor did penicillin). Penicillium culture Staphylococcus culture