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Transcript
Introduction Microbiology 2011 What is a microbiology? • Study of living organisms of microscopic size, which include bacteria, fungi, algae, protozoa and the infectious agents at the borderline of life that are called viruses. Why study microbiology? • Nutrient production • Decomposition • Biotechnology – production of foods, drugs and vaccines • Genetic engineering • Bioremediation • Infectious disease 3 Why study microbiology? • Microorganism are closely associated with the health and welfare of human beings; some are beneficial and others are detrimental. • Microorganisms have some characteristics which make them ideal specimen for the study of numerous fundamental life processes. • Microorganisms have a wider range of physiological and biochemical potentialities than all other organism. • Eg. Some bacteria are able to utilize atmospheric nitrogen for the synthesis of proteins and other complex nitrogenous compounds. • Some microorganisms synthesize all their vitamins. Major Field of applied Microbiology 1. Medical Microbiology- causative agents of disease and diagnostic procedure for identification of causative agent; preventive measures. 2. Aquatic microbiology: water microbiological examination; degradation of waste, ecology. purification, biological 3. Aero microbiology: contamination and spoilage, dissemination of diseases. 4. Food microbiology: food preservation and preparation, food borne diseases and their prevention. 5. Agricultural microbiology: soil fertility, plant and animal disease. 6. Industrial microbiology: production of medicinal products such as antibiotics and vaccines, fermented beverages, industrial chemicals, production of proteins and hormones by genetically engineered microorganisms. 7. Exomicrobiology: exploration for life in outer space. 8. Geochemical microbiology: coal, minerals and gas formation, prospect for deposits of coal, oil and gas; recovery of minerals from low grade ions. History of microbiology • Microbiology began when people learnt to grind lenses from pieces of glass and combine them to produce magnification great enough to enable microbes to be seen. Antonie van Leeuwenhoek • First to observe living microbes • His single-lens magnified up to 300X (1632-1723) History • In 13th century Roger Bacon (1220-1292)Diseased is produced by invisible living creatures. • Girolamo Fracastro (1483-1553)- First to recognize the existence of tiny particles. These tiny particles cause a contagious disease by direct contact. Spontaneous Generation versus Biogenesis. • Aristotle (384-322 B.C)- animal might originate spontaneously from the soil, decaying food, warm rain and even dirty shirts. • Virgil (70-19B.C)- maggot could be produced by exposing meat to air and warmth. • Francesco Redi (1626-1697): he placed a meat in a jar and covered with a gauge. Attracted by the odor of the meat, flies laid eggs on the covering, and from the egg maggot developed. 1947, John Needham- while experimenting with meat exposed to hot ashes, • observed the appearance of organism not present at the start of the experiment. • He concluded that the bacteria originated from meat. • Lazarro Spallanzani(1729-1790): Boiled beef broth for an hour and then sealed the flasks. • No microbes appeared following incubation. • It failed to convince Needam, who insisted that air is essential to the spontaneous production of microscopic beings and that it had been excluded from the flask by sealing them. • Frantz Schule (1815-1873) passed air into his flask through red-hot tubes. In neither case did microbes appear. • H.Schroder and T. Von Dusch: performed a more convincing experiment by passing air through cotton into flask containing heated broth. Thus, the microbes were filtered out of air by the cotton fibres so that the growth did not occur and a basic technique of plugging bacteria culture. Spontaneous Generation Theory • Spontaneous generation – “Living things arise from nonliving things” – Belief that some forms of life could arise from vital forces present in nonliving or decomposing matter • Maggots found in rotting meat arose from a nonliving factor • Microorganisms found in broth that made it cloudy appeared from a nonliving factor • Germ theory of disease: – “Microorganisms can invade other organisms and cause disease” – Many diseases are caused by the growth of microbes in the body and not by sins, bad character, or poverty, etc. Germ Theory of Disease Theory of biogenesis • Louis Pasteur: – Worked in the wine industry • Had knowledge about yeast producing alcohol -Goose-neck flasks – Tipping the flask would allow the microbes to enter the infusion • Cause them to become cloudy • Main experiment that helped disprove spontaneous generation Louis Pasteur • Louis Pasteur performed experiment that ended the argument of all time. • “There is no condition today in which you can affirm that microscopic beings come into the world without germ, without parents like themselves” • he prepared a flask with a long narrow goose neck opening. • The nutrient were heated in the flask • air untreated and unfiltered could pass in or out but germ settle in the goose neck and • no microbes appeared in the solution. Louis Pasteur •Pasteur discovered that some yeasts made good tasting wine •Mixtures of microbes competed with yeast and made wine taste oily or sour •Developed Pasteurization to deal with this problem –Heated the wine to 56°C without oxygen present for 30 minutes •Developed a rabies vaccine • Fermentation- with the final result of Pasteurization • He found fermentation of fruits and grains resulting in alcohol was brought about by microbes. • He suggested that undesirable types of microbes might be removed by heating not enough to hurt the flavor of the fruit juice but enough to destroy a very high percentage of microbial population. • Heating juice at a temperature of 62.8 degree (145ºF) for half an hour did the job. • Developed immunization for anthrax in cattle and rabies in human. • No one knew what caused infections when Louis Pasteur was a boy in the early 1800s. • No one knew that germs spread disease. • There were no antibiotics or other drugs. • Many people died from infections. • Pasteur discovered that bacteria cause many diseases. • He showed that bacteria get into living things and then multiply. • He proved that diseases could be cured by stopping the spread of bacteria. • This important discovery is called the germ theory of disease. • • • • • • HOW PASTEUR HELPED INDUSTRY Louis Pasteur was born in France in 1822. He studied physics and chemistry in Paris. As a professor of chemistry, he worked on problems that affected French industry. The wine-making industry in France was in trouble during the mid-1800s because much of the wine was spoiling. Pasteur discovered that germs were getting into the wine and turning it sour. He found that heat killed these germs and prevented the wine from spoiling.. • Pasteur later applied his discovery to milk. • His way of heating foods to kill bacteria is now called pasteurization. • Pasteur then discovered how to make vaccines to protect people and animals against disease. • He observed that animals infected with a disease sometimes became immune to the disease—that is, protected from getting the disease again. • Pasteur found that he could weaken germs in his laboratory. • When he put weakened germs into the bodies of animals, the animals became immune to the disease caused by the germs. • Pasteur made a vaccine to protect sheep against a disease called anthrax. Louis Pasteur (1822-1895) • Showed microbes caused fermentation and spoilage • Disproved spontaneous generation of microorganisms • Developed pasteurization • Demonstrated what is now known as Germ Theory of Disease • Developed a rabies vaccine and vaccine for Anthrax in cattle. 24 Robert Koch • Robert Koch – Linked a microscopic organism with a specific disease (anthrax) – Developed method to grow bacteria in pure cultures (cultures containing only one kind of organism) • Used solidified gelatin from potato slices mixed with agar • Creates a firm surface that microbes could grow on Robert Koch Robert Koch- Microbes cause disease in animals. • While studying the anthrax disease in cattle, Koch found rod shaped organisms in the blood of the disease animals. • To test if these organisms were the causative agent of the disease, he injected healthy mice with the blood of the diseased animal. • To his surprise he found that the disease was transmissible to the mice. • He removed a piece of spleen from the diseased mice and transferred it to a sterile serum and obtained a good growth of the rod-shaped organism. • By injecting these organism into healthy animals, he was able to reproduce the disease. • from these studies he was able to lay down certain basic criteria for the identification of microorganism as causative agent of disease. • These criteria are known as Koch’s postulates. Koch’s Postulates 1. A specific organism can always be found in association with a given disease. 2. The organism can be isolated and grown in pure culture in the laboratory. 3. The pure culture will produce the disease when inoculated into a susceptible animal. 4. It is possible to recover the organism in pure culture from the experimentally injected animals. Koch’s Postulate • The microorganism must be present in every case of the disease but absent from healthy organism. • 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 from the diseased host. END