Introduction to Microbiology PDF

MICROBIOLOGY & PARASITOLOGY Introduction to Microbiology Microbiology-The Science Dennis Espineli Salcedo, PhD School of Medical Technology CONTENTS 1. Introduction 2. What Is Microbiology? 3. Why Study Microbiology? 4. First Microorganisms on Earth 5. Earliest Known...

MICROBIOLOGY & PARASITOLOGY Introduction to Microbiology Microbiology-The Science Dennis Espineli Salcedo, PhD School of Medical Technology CONTENTS 1. Introduction 2. What Is Microbiology? 3. Why Study Microbiology? 4. First Microorganisms on Earth 5. Earliest Known Infectious Diseases 6. Pioneers in the Science of Microbiology 7. Careers in Microbiology What Is Microbiology? Biology is the study of living organisms. Microbiology is an advanced biology course dealing with the study of microbes, which are extremely small (microscopic) living organisms and certain nonliving entities. Living microbes are known as cellular microbes or microorganisms; examples include bacteria, archaea, some algae, protozoa, and some fungi. Nonliving microbes are known as acellular microbes or infectious particles; examples include viroids, prions, and viruses. Microbes are ubiquitous (i.e., they are found virtually everywhere). Acellular and Cellular Microbes  What Is Microbiology? The microbes that cause disease are sometimes referred to as “germs.” The scientific term for disease-causing microbes is pathogens. Microbes that do not cause disease are called nonpathogens; majority of microbes are nonpathogens.  What Is Microbiology? Microbes that live on and in our bodies are referred to as our indigenous microbiota Some members of our indigenous microbiota are opportunistic pathogens Opportunistic pathogens are microbes that can cause disease, but usually do not; they can be thought of as microbes that are awaiting the opportunity to cause disease Pathogens cause two categories of diseases: 1. Infectious diseases 2. Microbial intoxications Categories of Diseases Caused by Pathogens  What Is Microbiology? Microbes play significant roles in our lives; they are essential for life on this planet. Examples: Photosynthetic algae and bacteria (such as cyanobacteria) produce much of the oxygen in our atmosphere. Microorganisms are involved in the decomposition of dead organisms and waste products. Saprophytes are organisms that live on dead and/or decaying organic matter. The use of microbes to clean up toxic wastes and other industrial waste products is known as bioremediation. Microbes as Saprophytes  Why Study Microbiology? Many microbes play essential roles in various elemental cycles, such as the carbon, nitrogen, oxygen, sulfur, and phosphorus cycles. Algae and bacteria serve as food for tiny animals; they are important links in food chains. Microbes that live in the intestinal tracts of animals aid in the digestion of food and produce beneficial substances. For many years, microorganisms have been used as “cell models”; the more the scientists learned about microbial cells, the more they learned about cells in general. Microbes and Nitrogen Fixation  Why Study Microbiology? (cont.) Microbes are used in many industries, such as food, beverage, chemical, and antibiotic industries and in genetic engineering. In genetic engineering, a gene(s) from one organism is inserted into a bacterial or yeast cell; the cell that receives the new gene(s) is then capable of producing the gene product(s) coded for by the new gene(s). The use of living organisms or their derivatives to make or modify useful products or processes is called biotechnology. Products Requiring Microbial Participation in the Manufacturing Process Microbes and the Food Chain  First Microorganisms on Earth Fossils of primitive microorganisms date back about 3.5 billion years. Candidates for the first microorganisms on Earth are archaea and cyanobacteria. Infectious diseases of humans and animals have existed for as long as humans and animals have inhabited the planet. Earliest known account of pestilence occurred in Egypt in about 3180 BC. Pioneers in the Science of Microbiology Anton van Leeuwenhoek (1632–1723) The first person to see live bacteria and protozoa. The Father of Microbiology. The Father of Bacteriology. The Father of Protozoology. He was a fabric merchant, a surveyor, a wine assayer, and a minor city official in Delft, Holland. As a hobby, he ground tiny glass lenses, which he mounted in small metal frames, thus creating what today are known as single-lens microscopes or simple microscopes.  Spontaneous Generation Theory John Needham By 1745 an English scientist used microscopic observations to support the theory of abiogenesis. To test this, he boiled meat broth for several minutes in a loosely sealed flask. (allow to cool down the flask) Immediately after boiling he saw under the microscope that the broth had no living things. After a few days he examined the flask and found microorganism.  Spontaneous Generation Theory Disproving Spontaneous Generation Francesco Redi Proved that maggots did not come from a piece of meat Lazaro Spallanzani Heated the soup before culturing.  Louis Pasteur Swan Neck Experiment Pasteur filled a flask with medium, heated it to kill all life, and then drew out the neck of the flask into a long S. This prevented microorganisms in the air from entering the flask yet allowed air to flow freely. If the swan neck was broken, microbes could enter the flask and grow Pioneers in the Science of Microbiology Louis Pasteur (1822–1895) French chemist who made numerous contributions to microbiology Investigated different fermentation products Developed the pasteurization process Discovered life forms that could exist without oxygen (anaerobes) Developed several vaccines, including rabies and anthrax vaccines Pioneers in the Science of Microbiology Robert Koch (1843–1910) German physician who made numerous contributions to microbiology Made significant contributions to the germ theory of disease Discovered that Bacillus anthracis produced spores Developed methods of fixing and staining bacteria Developed methods to cultivate bacteria  Koch’s Postulates During the mid- to late-1800s, Robert Koch and his colleagues established an experimental procedure to prove that a specific microbe is the cause of a specific infectious disease. This scientific procedure, published in 1884, became known as Koch’s Postulates.  Koch’s Postulates Building on the early work of Louis Pasteur and the germ theory of disease, Robert Koch established the basic scientific requirements used to demonstrate that each specific disease is caused by a specific microorganism. The first direct demonstration of the role of bacteria in causing disease came from the study of anthrax by the German physician. These requirements were based on Koch’s experiments with anthrax isolated from diseased hosts and are known as “Koch’s Postulates”.  Koch’s Postulates (cont’d) If an organism fulfills Koch’s Postulates, it has been proven to be the cause of that infectious disease. Koch’s Postulates helped prove the germ theory of disease. Koch gave a tremendous boost to the development of microbiology by stressing laboratory culture and identification of microorganisms. Circumstances do exist in which Koch’s Postulates cannot be fulfilled.  Careers in Microbiology A microbiologist is a scientist who studies microbes. There are many career fields within the science of microbiology: Bacteriology Phycology Protozoology Mycology Parasitology Virology). Medical microbiology Involves the study of pathogens, the disease they cause, and the body’s defenses against disease Concerned with epidemiology, transmission of pathogens, disease-prevention measures, aseptic techniques, treatment of infectious diseases, immunology, and production of vaccines