BB-123 Basic Microbiology PDF

BB-123: Basic Microbiology 1. Concept of origin of life: Golden age of Microbiology, Chemical evolution, Abiogenesis and biogenesis, Spontaneous generation theory, Contribution of Louise Pasture, Robert Koch, Alexander Fleming in the development of microbiology and their early discoveries, Eukaryoti...

BB-123: Basic Microbiology 1. Concept of origin of life: Golden age of Microbiology, Chemical evolution, Abiogenesis and biogenesis, Spontaneous generation theory, Contribution of Louise Pasture, Robert Koch, Alexander Fleming in the development of microbiology and their early discoveries, Eukaryotic and Prokaryotic microorganisms and their differentiation, Microscopy and characteristic of different types of microscopes. 3. Fungi: Brief outline on growth and reproduction, Importance in natural process. 6. Role of Microorganisms: Carbon, Nitrogen and sulfur cycle, Biosynthetic substances produced by microorganisms: Vinegar and penicillin production, Importance of microorganisms in industrial process and agriculture. 7. Microbes and diseases: Natural resistance, Pathogenicity and virulence, Microbial toxins. Ref: 2. Microbiology: M. J. Pelczar, Jr; E.C.S. Chan & N.R. Krieg. 3. Microbiology: An Introduction: G.J. Tortora et al. The Benjamin Cunnings Publishing Co. 1. Concept of origin of life: Golden age of Microbiology Contribution of Louise Pasture, Robert Koch, Alexander Fleming in the development of microbiology and their early discoveries, Eukaryotic and Prokaryotic microorganisms and their differentiation Chemical evolution Abiogenesis and biogenesis Spontaneous generation theory Microscopy and characteristic of different types of microscopes.  Microbiology Microbiology is the 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. It is concerned with their form, structure reproduction, physiology, metabolism, and classification. it includes the study of their distribution in nature, their relationship to each other and to other living organisms, their effects on human beings and on other animals and plants, their abilities to make physical and chemical changes in our environment, and their reactions in physical and chemical agents. Microorganisms are closely associated with the health and welfare of human beings; some microorganisms are beneficial, and others are detrimental. A pathogen is defined as an organism causing disease to its host. microbiome The microbiome is the community of microorganisms (such as fungi, bacteria and viruses) that exists in a particular environment. An adult human is composed of about 30 trillion body cells and harbors another 40 trillion bacterial cells. Microbes that live stably in and on the human body are called the human microbiome, or microbiota. Humans and many other animals depend on these microbes to maintain good health. Bacteria in our intestines, including E. coli, aid digestion and even synthesize some vitamins that our bodies require, including B vitamins for metabolism and vitamin K for blood clotting. Golden Age of Microbiology  The First Golden Age of Microbiology The period from 1857 to 1914 has been appropriately named the First Golden Age of Microbiology. Rapid advances, spearheaded mainly by Pasteur and Robert Koch, led to the establishment of microbiology. Discoveries included both the agents of many diseases and the role of immunity in preventing and curing disease.  Louis Pasteur Fermentation and Pasteurization One of the key steps that established the relationship between microorganisms and disease occurred when a group of French merchants asked Pasteur to find out why wine and beer soured. They hoped to develop a method that would prevent spoilage when those beverages were shipped long distances. At the time, many scientists believed that air converted the sugars in these fluids into alcohol. Pasteur found instead that microorganisms called yeasts convert the sugars to alcohol in the absence of air. This process, called fermentation, is used to make wine and beer. Souring and spoilage are caused by different microorganisms, called bacteria. In the presence of air, bacteria change the alcohol into vinegar (acetic acid). Pasteur’s solution to the spoilage problem was to heat the beer and wine just enough to kill most of the bacteria that caused the spoilage. The process, called pasteurization, is now commonly used to reduce spoilage and kill potentially harmful bacteria in milk and other beverages as well as in some alcoholic beverages. Pasteurization involves heating liquids at high temperatures for short amounts of time. Pasteurization kills harmful microbes in milk without affecting the taste or nutritional value. Fermentation is the chemical breakdown of a substance by bacteria, yeasts, or other microorganisms, typically involving effervescence and the giving off of heat. The Germ Theory of Disease Before the time of Pasteur, effective treatments for many diseases were discovered by trial and error, but the causes of the diseases were unknown. The realization that yeasts play a crucial role in fermentation was the first link between the activity of a microorganism and physical and chemical changes in organic materials. This discovery alerted scientists to the possibility that microorganisms might have similar relationships with plants and animals—specifically, that microorganisms might cause disease. This idea was known as the germ theory of disease. In 1865, Pasteur was called upon to help fight silkworm disease, which was ruining the silk industry in Europe. Decades earlier, amateur microscopist Agostino Bassi had proved that another silkworm disease was caused by a fungus. Using data provided by Bassi, Pasteur found that the more recent infection was caused by a protozoan, and he developed a method for recognizing afflicted silkworm moths. Robert Koch The first proof that bacteria actually cause disease came from Robert Koch in 1876. Koch, a German physician, was Pasteur’s rival in the race to discover the cause of anthrax, a disease that was destroying cattle and sheep in Europe. Koch discovered rod-shaped bacteria now known as Bacillus anthracis in the blood of cattle that had died of anthrax. He cultured the bacteria on nutrients and then injected samples of the culture into healthy animals. When these animals became sick and died, Koch isolated the bacteria in their blood and compared them with the originally isolated bacteria. He found that the two sets of blood cultures contained the same bacteria. Koch thus established Koch’s postulates, a sequence of experimental steps for directly relating a specific microbe to a specific disease. Vaccination The smallpox vaccine is an example. Almost 70 years before Koch established that a specific microorganism causes anthrax, Edward Jenner, a young British physician, embarked on an experiment to find a way to protect people from smallpox. The Second Golden Age of Microbiology After the relationship between microorganisms and disease was established, medical microbiologists next focused on the search for substances that could destroy pathogenic microorganisms without damaging the infected animal or human. Treatment of disease by using chemical substances is called chemotherapy. Chemicals produced naturally by bacteria and fungi that act against other microorganisms are called antibiotics. Chemotherapeutic agents prepared from chemicals in the laboratory are called synthetic drugs. Alexander Fleming A Fortunate Accident—Antibiotics The first antibiotic was discovered by accident. Alexander Fleming, a Scottish physician and bacteriologist, almost tossed out some culture plates that had been contaminated by mold. Fortunately, he noticed the curious pattern of growth on the plates—a clear area where bacterial growth had been inhibited encircled the mold. Fleming was looking at a mold that inhibited growth of a bacterium. The mold became known as Penicillium chrysogenum and the mold’s active inhibitor was called penicillin. Thus, penicillin is an antibiotic produced by a fungus. The Second Golden Age of Microbiology began in the 1940s, when the enormous usefulness of penicillin became apparent and the drug came into common use. Eukaryotic and Prokaryotic