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Chapter 1 Introduction • Ubiquitous – they are everywhere • Air, water, Soil ( microbes are all around us) • Normal flora – found in the gastrointestinal tract, genitourinary tract, respiratory tract, skin. • Beneficial aspects and harmful aspects • Normal flora protect us from diseases. They suppress the growth of pathogens. • E. coli in the large intestine makes vitamin K – used for blood clotting. • Aquatic environments. Unicellular algae – bottom of the food chain. • Unicellular algae > tiny fish > large fish > shark. • Algae are autotrophs. They use CO2 and water to make sugar. • Soil microbes are involved in recycling chemical elements. • Breakdown cellulose and release CO2. • Making food products (yogurt, cheese, bread). Yeast + flour > dough • Small ball of dough -----large ball of dough • Therapeutic substances – genetic engineering is used to force E. coli to make human insulin. • Bioremediation – microbes are used to clean up chemical pollutants (oil spills) in the environment. • Insecticide – BT toxin is sprayed on plants. • Sewage treatment – breakdown organic matter to produce methane. • Harmful aspects • Tuberculosis, Lyme disease • Spoilage of food products. Milk ----- sour. Lactose --- acids. • History of microbiology • 1665 Robert Hooke – plant materials (leaves and stems). Little boxes – cells. • 1673 – 1723 Anton van Leeuwenhoek observe microbes under the microscope. • Rain water, scrapings from his teeth. • Called the microbes animalcules. • Spontaneous generation theory – life could arise from nonliving matter. • Decaying meat give birth to maggots (larvae of flies) Fine net No maggots Needham 1745 • Rudolph Virchow – theory of biogenesis. • Life could arise only from pre-existing living cells. • 1861 Louis Pasteur disproved the spontaneous generation theory. Pasteur’s experiment S shaped curve S shaped curveS shaped curve S shaped curve • Microbes are found in the air, in liquids and on solids. • Foundation for the aseptic procedure used in the lab to prevent contamination • 1857 – discovered fermentation. • Yeast converted sugars in the grapes to alcohol and CO2 in the absence of O2. • 1864 – came up with pasteurization. Beverages such as milk are heated enough to kill microbes without destroying the flavor of the beverages. Germ theory of disease • A belief microbes could cause diseases. • 1860s Joseph Lister treated surgical wounds with disinfectant. • 1876 Robert Koch proved the germ theory of disease. • Animals such as cattle were dying of a disease. • Drew blood from the animals that had died of the disease. • Isolated a rod-shaped bacterium (isolate #1) • Grew bacterium in the lab and obtained a pure culture of the bacterium. • Injected bacterium into healthy animals. • They got sick and died. He isolated rod shaped bacterium from these animals (isolate #2) • Compared the 2 isolates and found that they were identical. • Anthrax. Bacillus anthracis. • The above steps are known as Koch’s postulates. • They are used even today to determine the causative agent of a mysterious infectious disease. • 1928 Alexander Fleming discovered penicillin. • • • • Naming organisms 1735 Carolus Linnaeus – binomial Genus and species Latin – describe the organism, honor a scientist. • Staphylococcus aureus • Escherichia coli Diversity of Microorganisms • Bacteria – prokaryotic • Pre-nucleus – DNA is NOT surrounded by a membrane • Unicellular • Heterotroph – get energy from organic molecules. • Cell walls - peptidoglycan • • • • • Fungi – yeasts and molds Eukaryotic – true nucleus Unicellular/multicellular Cell walls – chitin All are heterotrophs • • • • • • Protozoa – eukaryotic Unicellular Heterotophs Algae – eukaryotic Unicellular/multicellular Autotrophs - photosynthesize • • • • • • Viruses – acellular Either have DNA or RNA Obligate intracellular parasites Helminths – multicellular Worms Eggs are microscopic Classification of organisms • • • • • 1969 Robert whittaker 5 kingdom system Classification based on Cell type - prokaryotic/eukaryotic Cellular organization – unicellular/multicellular • Nutritional requirements – photosynthetic/nonphotosynthetic Classification of organisms • Prokaryotae (monera) – prokaryotic organisms – bacteria • Protista - protozoa • Fungi – Yeasts and molds • Plant – ferns, trees, flowering plants • Animal – worms, insects, vertebrates • • • • • • 3 domains Ribosomal RNA sequence Archaea, Bacteria, Eukarya Bacteria – prokaryotic Normal flora, pathogens Peptidoglycan • • • • • • Archaea Prokaryotic Unusual, extreme environments Salt lakes, dead sea Do not have peptidoglycan cell wall pseudomurein • Eukarya • All the eukaryotic organisms • Protozoa, fungi, plants and animals