Microbiology Lecture 1 PDF

National University for Science Microbiology \ theory and Technology Second stage College of Pharmacy Lecture 1...

National University for Science Microbiology \ theory and Technology Second stage College of Pharmacy Lecture 1 Assist. Prof. Dr. Riyad E. Abed INTRODUCTION Did you know that you're mostly microbes? There are more microbial cells in your body than your own cells! Microbes are found everywhere: in and on your body, in streams and rocks, on your smart phone screen, and in your food. Despite their bad reputation, microbes are mostly useful or have a neutral effect on our lives. Microbiology is the science dealing with study of very small organisms that cannot be seen with naked eye these organisms are called microorganisms. The nature of microorganisms makes them both easy and difficult to study. Easy, because they reproduce so rapidly and can usually be grown in large numbers in the laboratory. Difficult, because we can’t observe or analyze them without special techniques, especially the use of microscopes. Microbiology is one of the largest and most complex of the biological sciences because it integrates subject matter from many diverse disciplines. Microbiologists study every aspect of microbes—their genetics, their physiology, characteristics that may be harmful or beneficial, the ways they interact with the environment, the ways they interact with other organisms, and their uses in industry and agriculture. Microbiology: is the study of microorganism, a large and diverse group of microscopic organisms that exist a single cell or cell cluster; it also includes viruses which are microscopic but not cellular. Microorganisms have a tremendous impact on all life and the physical and chemical makeup of our planet. They are responsible for cycling the chemical elements essential for life, including carbon, nitrogen, sulphur, hydrogen, and oxygen; more photosynthesis is carried out by microorganisms than by green plants. Furthermore, there are 100 million times as many bacteria in the oceans (13 × 10 28) as there are stars in the known universe. Microorganisms were first seen and described by the Dutch lens- maker Antoine van Leeuwenhoek (1632–1723). 1 Microbial Divisions The field of microbiology includes the study of bacteria, fungi, protozoa and viruses. Bacteriology: is the science dealing with the study of bacteria. Mycology: is the science dealing with the study of fungi. Protozology: is the science dealing with the study of protozoa. Virology: is the science dealing with the study of viruses. Immunology: is the study of host's defense mechanisms against disease, also study the interaction between human and disease agents (pathogenic microbes). The field of microbiology includes the followings: Microbial physiology: The study of microbial growth, microbial metabolism and microbial cell structure. Microbial genetics: The study of the genetic information in microorganisms. Cellular microbiology: Study of cell biology. Medical microbiology: The study of microbial pathogenesis, epidemiology, and immunology. Veterinary microbiology: The study of the role of microbes in animal medicine. Environmental microbiology: The study the function and diversity of microbes in their natural environments. Industrial microbiology: include industrial fermentation, Waste-Water treatment. And brewing. Food microbiology: The study of microorganisms causing fermentation, food spoilage and foodborne illness. Microscopy Beginning: - The human eye cannot see the things that has a diameter less than 100 Mm the eye cannot also differentiate between the separate particles when the distance between them less than 100 Mm. The diameter of most tissues cells are not more than 50 Mm the bacteria 15 Mm and viruses 0.25 Mm. History of Microbiology Pre-microbiology: The possibility that microorganisms existed was discussed for many centuries before their actual discovery in the 17th century. In 1546, Girolamo Fracastoro proposed that epidemic diseases were caused by transferable seed-like entities that could transmit infection by direct or indirect contact or even without contact over long distances. 2 Microorganisms were not described correctly until the 17th century. Why? The reason for this was that all these early studies lacked the microscope. The Microscope and Discovery of Microorganisms Antonie van Leeuwenhoek (1632–1723) was one of the first people to observe microorganisms, using a microscope of his own design, and made one of the most important contributions to biology. Robert Hooke was the first to use a microscope to observe living things. Hooke’s 1665 book, Micrographia, contained descriptions of plant cells. Before Van Leeuwenhoek’s discovery of microorganisms in 1675, it had been a mystery why grapes could be turned into wine, milk into cheese, or why food would spoil. Van Leeuwenhoek did not make the connection between these processes and microorganisms, but using a microscope, he did establish that there were forms of life that were not visible to the naked eye. Van Leeuwenhoek’s discovery, along with subsequent observations by Spallanzani and Pasteur, ended the long-held belief that life spontaneously appeared from non-living substances during the process of spoilage. Lazzaro Spallanzani (1729–1799) found that boiling broth would sterilize it and kill any microorganisms in it. He also found that new microorganisms could settle only in a broth if the broth was exposed to the air. Louis Pasteur (1822–1895) (father of biotechnology) expanded upon Spallanzani’s findings by exposing boiled broths to the air in vessels that contained a filter to prevent all particles from passing through to the growth medium. He also did this in vessels with no filter at all, with air being admitted via a curved tube (swan‐necked flasks) that prevented dust particles from coming in contact with the broth. By boiling the broth beforehand, Pasteur ensured that no microorganisms survived within the broths at the beginning of his experiment. Nothing grew in the broths in the course of Pasteur’s experiment. This meant that the living organisms that grew in such broths came from outside, as spores on dust, rather than spontaneously generated within the broth. Thus, Pasteur dealt the death blow to the theory of spontaneous generation and supported germ theory instead. He performed numerous experiments to discover why wine and dairy products became sour, and he found that bacteria were to blame. In the 1860’s, an English surgeon, Joseph Lister showed the role of MO in the wound contamination, and developed Lister system which came to be known as Antiseptic Surgery, 3 which includes the heat sterilization of instruments and the application of phenol to wound by means of dressings. Ferdinand Julius Cohn (1828 –1898) was a German biologist. His classification of bacteria into four groups based on shape (sphericals, short rods, threads, and spirals) is still in use today. In 1876, Robert Koch (1843–1910) established that microbes can cause disease. He found that the blood of cattle who were infected with anthrax always had large numbers of Bacillus anthracis. Koch found that he could transmit anthrax from one animal to another by taking a small sample of blood from the infected animal and injecting it into a healthy one, and this caused the healthy animal to become sick. He also found that he could grow the bacteria in a nutrient broth, then inject it into a healthy animal, and cause illness. Based on these experiments, he devised criteria for establishing a causal link between a microbe and a disease and these are now known as Koch’s postulates. Although these postulates cannot be applied in all cases, they do retain historical importance to the development of scientific thought and are still being used today. Koch postulates: 1. The suspected causative agent must be found in every case of disease. 2. This MO must be isolated from the infected individual and grown in a culture with no other types of MO. 3. When inoculation into normal healthy susceptible animal a pure culture of the agent must be producing the specific disease. 4. The same MO must be isolated from the experimentally infected host. Paul Ehrlich (1909) by him chemotherapy was introduced and the modern era of control treatment began with the use of chemicals that would kill or interfere with the growth of the disease agent without damaging the infected individual. In 1929, Alexander Fleming isolated a mold produced substance that inhibited bacteria but was nontoxic to lab animal. He named this antibacterial material Penicillin, which is one type of antibiotics. Up to data, many new approaches and techniques are developing that aid in the isolation, treatment, controlling, and prevention of infectious disease. Work with viruses could not be effectively performed until instruments were developed to help scientists see these disease agents. In the 1940s, the electron microscope was developed and perfected. In that decade, cultivation methods for viruses were also introduced, and the knowledge of viruses developed rapidly. With the development of vaccines in the 1950s and 1960s, such viral diseases as polio, measles, mumps, and rubella came under control. 4 The Importance of Microorganisms They have great impact on human lives and are used for different purposes as listed below: 1-Food: Nature uses microorganisms to carry out fermentation processes, and for thousands of years’ mankind has used yeasts, molds and bacteria to make food products such as bread, beer, wine, vinegar, yoghurt and cheese, as well as fermented fish, meat and vegetables. 2-Medicine: Microbes play a major role in the development, production, and future of medicine. Vaccines and antibiotics are only two of the hundreds of uses for microbes in the medical field. Microbes have played a significant role in the development of medical treatments. 3-Human health: relationship endo symbiotic human digestion: Microorganisms can form with other, larger organisms. For example, the bacteria that live within the digestive system contribute to gut immunity, synthesis carbohydrates, vitamins and ferment complex indigestible biotin and folic acid. Disease: Microorganisms are the cause of many infectious diseases. 4-Biotechnology: Production of foods, drugs, and vaccines using living organisms 5-Genetic engineering: Manipulating the genes of organisms to make new products 6-Bioremediation: Using living organisms to remedy an environmental problem Microbial Diversity: 6 Types of Microbes 5