MICROBIO 310 1st Edition Lecture 3Outline of Last Lecture II. 1.2 Microbial CellsIII. 1.3 Microorganisms and Their EnvironmentsIV. 1.4 Evolution and the Extent of Microbial LifeOutline of Current Lecture I. 1.5 The Impact of Microorganisms on HumansII. 1.6 The Historical Roots of MicrobiologyIII. 1.7 Pasteur and the Defeat of Spontaneous Generation IV. 1.8 Koch, Infectious Disease, and Pure Culture Microbiology Current Lecture1.5 The Impact of Microorganisms on Humans• Microorganisms can be both beneficial and harmful to humans• Emphasis typically on harmful microorganisms (infectious disease agents, or pathogens)• Many more microorganisms are beneficial than are harmful• Microorganisms as disease agents– Control of infectious disease during last century 1.5 The Impact of Microorganisms on Humans• Microorganisms and Agriculture– Many aspects of agriculture depend on microbial activities • Positive impactsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.– nitrogen-fixing bacteriaconvert N2 into nitrites/nitrates– cellulose-degrading microbes in the rumen (stomach compartment of cows)– regeneration of nutrients in soil and water• Negative impacts– diseases in plants and animals• Microorganisms and Food – Negative impacts• Food spoilage by microorganisms requires specialized preservation of many foods– Positive impacts• Microbial transformations (typically fermentations) yield:– dairy products (e.g., cheeses, yogurt, buttermilk)– other food products (e.g., sauerkraut, pickles, leavened breads, beer)• Microorganisms, Energy, and the Environment– The role of microbes in biofuels production • For example: methane, ethanol, hydrogen– The role of microbes in cleaning up pollutants (bioremediation)• Microorganisms and Their Genetic Resources – Exploitation of microbes for production ofantibiotics, enzymes, and various chemicals– Genetic engineering of microbes to generate products of value to humans, such as insulin (biotechnology)o Uses recombinant DNAgenetically modified organisms (GMO)1.6 The Historical Roots of Microbiology• Microbiology began with the microscope• Robert Hooke (1635–1703): the first to describe microbes– Illustrated the fruiting structures of molds • Antoni van Leeuwenhoek (1632–1723): the first to describe bacteria – Further progress required development of more powerful microscopes• Ferdinand Cohn (1828–1898): founded the field of bacterial classification and discovered bacterial endospores1.7 Pasteur and the Defeat of Spontaneous Generation• Louis Pasteur (1822–1895)– Discovered that living organisms discriminatebetween optical isomers– Discovered that alcoholic fermentation was a biologically mediated process (originally thought to be purely chemical)– Disproved theory of spontaneous generation• Led to the development of methods for controlling the growth of microorganisms (aseptic technique)– Developed vaccines for anthrax, fowl cholera, and rabies1.8 Koch, Infectious Disease, and the Rise of Pure Cultures• Robert Koch (1843–1910)– Demonstrated the link between microbes and infectious diseases• Identified agents that cause anthrax and tuberculosis– Developed techniques (solid media) for obtaining pure cultures of microbes, some still in existence today– Koch’s postulates o 1. The suspected pathogen must be present in all cases of the disease andabsent from healthy animals.o 2. The suspected pathogen must be grown in pure culture.o 3. Cells from the pure culture of the suspected pathogen must cause disease in a healthy animal.o 4.The suspected pathogen must be reisolated and shown to be the same as the original.– Awarded Nobel Prize for Physiology andMedicine in 1905• Koch’s Postulates Today– Koch’s postulates apply for diseases that have an appropriate animal model– Remain as the “gold standard” in medical microbiology, but not always possible to satisfy all postulates for every infectious disease– Animal models not always available• For example: cholera, rickettsias, chlamydias• Koch and the Rise of Pure Cultures– Discovered that using solid media provided a simple way of obtaining pure cultures– Began with potato slices, but eventually devised uniform and reproducible nutrient solutions solidified with gelatin and