Published on September 5, 2010
Slide 1: Biodiversity of Microorganisms Slide 2: : Introduction to Microbiology, History & scope Microbiology: - In the broadest sense, microbiology is the study of all organisms that are invisible to the naked eye-that is the study of microorganisms. - Its subjects are viruses, bacteria, many algae and fungi, and protozoa. - The importance of microbiology and microorganisms can not be overemphasized. - Microorganisms are necessary for the production of bread, cheese, beer, antibiotics, vaccines, vitamins, enzymes, etc. - Modern biotechnology rests upon a microbiological foundation. Microorganisms: - Microorganisms are everywhere; almost every natural surface is colonized by microbes, from body to ocean. Some microorganisms can live hot springs, and others in frozen sea ice. - Most microorganisms are harmless to humans; You swallow millions of microbes every day with no ill effects. In fact, we are dependent on microbes to help us digest our food. - Microbes also keep the biosphere running by carrying out essential functions such as decomposition of dead animals and plants. They make possible the cycles of carbon, oxygen, nitrogen and sulfur that take place in terrestrial and aquatic systems. - Microorganisms have also harmed humans and disrupted society over the millennia. Slide 3: - They sometimes cause diseases in man, animals and plants. They are involved in food spoilage. - Infectious diseases have played major roles in shaping human history (decline of Roman Empire & conquest of the New World. - The "Great Plague", reduced population of western Europe by 25%. - Smallpox and other infectious diseases introduced by European explorers to the Americas in 1500's were responsible for decimating Native American populations. - Until late 1800's, no one had proved that infectious diseases were caused by specific microbes. Discovery of Microorganisms: - Invisible creatures were thought to exist long before they were observed. - Antony van Leewenhoek (1632 – 1723) who invented the first microscope (50 – 300x), was the first to accurately observe and describe microorganisms. Spontaneous Generation Myths : Spontaneous Generation Myths Snakes from horse hairs in stagnant water Mice from grain and cheese wrapped in a sweater Maggots from rotting meat Fleas from hair Flies from fresh and rotting fruit Mosquitoes from stagnant pondwater Eels from slimy mud at the bottom of the ocean Locusts from green leaves Raccoons from hollow tree trunks Termites are generated from rotting wood Slide 5: Spontaneous Generation Conflict: - From earliest times, people believed that Living organisms could developed from nonliving or decomposing matter. - The SGT was challenged by Redi, Needham, Spallanzani - Louis Pasteur (1822-1895) settled the conflict once for all; heated the necks of flasks and drew them out . Role of Microorganisms in Disease: - Bassi – showed that silkworm disease was caused by a fungus. - Berkeley and Pasteur showed that Microorganisms caused disease. - Joseph Lister – developed system for sterile surgery - Robert Koch (1843 – 1910) established the relationship between Bacillus anthracis and anthrax; also isolated the bacillus that causes tuberculosis. - Charles Chamberland (1851-1908) discovered viruses and their role in disease. Slide 6: Supported by: Aristotle (384-322 BC) – Believed that imple invertebrates coould arise by spontaneous generation John Needham (1713-1781) – Boiled mutton broth, then sealed and still observed growth after a period of time Lazarro Spallanzani (1729-1799) No growth in sealed flask after boiling – proposed that air was needed for growth of organisms Felix Pouchet (1859) – Proved growth without contamination from air Slide 7: Disproved by: Francesco Redi (1626-1697) – maggot unable to grown on meat if meat was covered with gauze Schwann, Friedrich Schroder and von Dusch (1830s) – Air allowed to enter flask but only after passing through a heated tube or sterile wool John Tyndall (1820-1893) – Omission of dust no growth. Demonstrated heat resistant forms of bacteria (endospores) Slide 8: History of Microbiology Many believed spontaneous generation: life can arise from non-living matter In 1668, the Italian physician Francesco Redi performed an experiment to disprove spontaneous generation. Can you think of an experiment that could disprove spontaneous generation? Slide 9: History of Microbiology Redi filled six jars with decaying meat. Slide 10: Louis Pasteur (1822 - 1895) trapped airborne organisms in cotton; he also heated the necks of flasks, drawing them out into long curves, sterilized the media, and left the flasks open to the air; no growth was observed because dust particles carrying organisms did not reach the medium, instead they were trapped in the neck of the flask; if the necks were broken, dust would settle and the organisms would grow; in this way Pasteur disproved the theory of spontaneous generation Slide 11: Koch’s Postulates: - Microorganism must be present in every case of the disease but absent from healthy individuals. - The suspected microorganism must be isolated and grown in pure cultures. - The disease must result when the isolated microorganism is inoculated into a healthy host. - The same microorganism must be isolated from the disease host. Isolation of Microorganisms: - During Koch’s studies, it became necessary to isolate suspected bacterial pathogens. - He cultured bacteria on the sterile surfaces of cut, boiled potatoes Not satisfactory. - Regular liquid medium solidified by adding gelatin gelatin melted @ T>28°C. - Fannie Eilshemius suggested use of agar; 100°C to melt, 50 °C to solidify. - Richard Petri developed petri dish, a container for solid culture media. Louis Pasteur (1822 – 1895): - Developed vaccines for Chickenpox, anthrax, rabies - Demonstrated that all fermentations were due to the activities of specific yeasts and bacteria. Slide 12: - Discovered that fermentative microorganisms were anaerobic and could live only in absence of oxygen. - Developed Pasteurization to preserve wine during storage. Important: Foods Other Developments… - Winogradsky made many contributions to soil microbiology; discovered that soil bacteria could oxidize Fe, S and ammonia to obtain energy. - Isolated Anaerobic nitrogen-fixing bacteria; studied the decomposition of cellulose. - Together with Beijerink, developed the enrichment-culture technique and the use of selective media. - Early 40’s, Microbiology established closer relationship with Genetics and Biochemistry; microorganisms are extremely useful experimental subjects. - e.g. Study of relationship between genes and enzymes; evidence that DNA is the genetic material; - Recently, Microbiology been a major contributor to the rise of Molecular Biology. - Studies on Genetic code; mechanisms of DNA, RNA, and Protein synthesis; regulation of gene expression; control of enzyme activity. - Development of Recombinant DNA Technology and Genetic Engineering. Slide 13: - Organisms divided into 5 Kingdoms: Monera – all procaryotes Plantae – multicellular Animalia - multicellular Protista – unicellular or colonial eucaryotic cells lacking true tissues; includes algae, protozoa & simpler fungi Fungi – eucaryoutic; includes molds, yeasts and mushrooms Scope of Microbiology: - Many microbiologists are primarily interested in the biology of microorganisms, while others focus on specific groups; - Microbiology has an impact on medicine, agriculture, food science, ecology, genetics, biochemistry, immunology, and many other fields. - Virologists - viruses - Bacteriologists - bacteria - Phycologists – algae - Mycologist -fungi Slide 14: - Protozoologists – protozoa - Medical Microbiology: deals with diseases of humans and animals; identify and plan measures to eliminate agents causing infectious diseases. - Immunology: study of the immune system that protects the body from pathogens. - Agricultural Microbiology: impact of microorganisms on agriculture; combat plant diseases that attack important food crops. Food and Dairy Microbiology: prevent microbial spoilage of food & transmission of food-borne diseases (e.g. salmonellosis); use microorganisms to make food such as cheeses, yogurts, pickles, beer, etc. - Industrial Microbiology: using microorganisms to make products such as antibiotics, vaccines, steroids, alcohols & other solvents, vitamins, amino acids, enzymes, etc. - Genetic Engineering: Engineered microorganisms used to make hormones, antibiotics, vaccines and other products. - Since viruses are acellular and possess both living and nonliving characteristics, they are considered neither prokaryotic nor eukaryotic. They will be discussed in separate section of the course.