IGMC 201 Introduction to Microbial World PDF

IGMC 201 INTRODUCTION TO MICROBIAL WORLD OUTLINES 1. Microbial World 2. Branches 3. Diversity 4. Characteristics of microbes 5. Importance 6. Binomial System of Scientific Nomenclature 7. Tools in microbiology 8. History/discovery of microbes MICROBIAL WORLD This r...

IGMC 201 INTRODUCTION TO MICROBIAL WORLD OUTLINES 1. Microbial World 2. Branches 3. Diversity 4. Characteristics of microbes 5. Importance 6. Binomial System of Scientific Nomenclature 7. Tools in microbiology 8. History/discovery of microbes MICROBIAL WORLD This refers to the world of microorganisms. "Microbe" is a short form of microorganism, meaning a small organism. This term was first used in 1878 by Sedillot. The study of microorganisms is called Microbiology, a subject that began with Antony van Leeuwenhoek’s discovery of microorganisms in 1675 using a microscope of his own design. Microorganisms are organisms that are too tiny to be seen with the naked eye except with the help of a microscope. They are the oldest form of life on the surface of the Earth. BRANCHES OF STUDY  1. Bacteriology: Study of bacteria 2. Mycology: Study of fungi and yeast 3. Virology: Study of viruses 4. Parasitology: Study of parasitic protozoans and helminths 5. Immunology: Study of the humoral and cellular immune response to disease agents and allergens Diversity of Microorganisms Microorganisms are very diverse; they include: Bacteria Fungi Algae Protozoa Virus Microbes can be found almost everywhere (in air, soil, food, water, and in the body, etc.). Characteristics of Bacteria 1. They are Prokaryotes. 2. They are single-celled.  3. Reproduce by binary fission. Example: Escherichia coli Characteristics of Fungi 1. Fungi are eukaryotic, non-vascular, non-motile, and heterotrophic organisms. 2. They may be unicellular or filamentous. 3. They reproduce by means of spores. 4. Fungi lack chlorophyll and hence cannot perform photosynthesis. Characteristics of Algae 1. They are eukaryotic. 2. Have cellulose cell walls. 3. They are photosynthetic. 4. Produce molecular oxygen and organic compounds. 5. They are part of the food chain. Characteristics of Protozoa 1. They are eukaryotic. 2. They are unicellular and microscopic. 3. May be motile by means of pseudopod, cilia, or flagella. Characteristics of Virus 1. Non-cellular. 2. Contain a protein coat called the capsid. 3. Have a nucleic acid core containing DNA or RNA (one or the other - not both). 4. Capable of reproducing only when inside a host cell. Importance of Microorganisms 1. Useful in studying molecular biology, biochemistry, and genetics. 2. Used in vaccine development. 3. Production of antibiotics. 4. Production of important biological enzymes (insulin). 5. Production of beer, wine, cheeses, and yoghourt. 6. Maintenance of soil fertility/digestion in cattle and humans. 7. Help in degrading toxic waste materials. Binomial System of Scientific Nomenclature Linnaeus introduced the binomial system of scientific nomenclature, which involves the genus and species epithet. Each organism has two names: the genus and species epithet. The names are italicized or underlined. The genus name is capitalized and species is in lowercase. Examples: Staphylococcus aureus: Describes the clustered arrangement of cells and golden-yellow color of colonies. Escherichia coli: Honors the discoverer, Theodor Escherich, and describes its habitat, the colon. After the first use, scientific names may be abbreviated with the first letter of the genus and full species epithet (e.g., E. coli). Tools of Microbiology 1. Compound light Microscope: Used to view live specimens. 2. Electron Microscope: Used to view non-living specimens. 3. Incubator: Used to keep microbes warm for growth. 4. Staining dye: Used to see structures better. 5. Microbial Culture: The act of growing microbes. 6. Petri dish: Container for microbe culture. 7. Culture media: Food for the microbes, e.g., Agar (from red algae) and nutrient broths. 8. Autoclave: For sterilisation of materials. HISTORY/DISCOVERY OF MICROORGANISMS The history of microorganisms involved four major eras: 1. Discovery era 2. Transition era 3. Golden era 4. Modern era DISCOVERY ERA Aristotle (384-322 BC) and others believed that living organisms could develop from non-living materials (e.g., maggots arising from decaying meat). This belief gave rise to the debate referred to as the "Spontaneous Generation Theory," which states that living organisms arise from non-living matter. Antony van Leeuwenhoek discovered microorganisms in 1675. TRANSITION ERA In this era: Francesco Redi (1697) showed that maggots would not arise from decaying meat when it is covered. John Needham (1781) supported the spontaneous generation theory. Lazzaro Spallanzani (1799) demonstrated that air carried germs to the culture medium and showed that boiled broth would not give rise to microscopic forms of life. GOLDEN ERA Louis Pasteur showed that microbes caused fermentation. He studied spoilage and introduced "Pasteurization" to prevent it. He is considered the father of medical microbiology. Pasteur suggested that mild heating at 62.8°C (145°F) for 30 minutes rather than boiling was enough to destroy undesirable organisms without ruining the taste of the product. Pasteur also invented the processes of pasteurization, fermentation, and developed effective vaccines (rabies and anthrax). Contributions of Louis Pasteur: 1. Coined the terms “microbiology,” “aerobic,” and “anaerobic.” 2. Disproved the theory of spontaneous generation. 3. Demonstrated that anthrax was caused by bacteria and produced the vaccine for the disease. 4. Developed a live attenuated vaccine for anthrax. Koch's Postulate In 1876, Robert Koch provided proof that a bacterium causes anthrax using experimental steps now called Koch’s Postulates: 1. The microbe must always be present in every case of the disease. 2. It must be isolated in pure culture on artificial media. 3. When inoculated into a healthy animal host, it should produce the same disease. 4. It must be isolated from the diseased animal again. MODERN ERA This era is known as the "Nobel Laureates Years." Major discoveries include: 1901: Von Behring discovered diphtheria antitoxin. 1902: Ronald Ross discovered the cause of malaria. 1905: Robert Koch identified the tuberculosis bacterium. 1908: Metchnikoff discovered phagocytosis. 1945: Flemming discovered penicillin. 1962: Watson and Crick identified DNA structure. 1968: Holley and Khorana deciphered the genetic code. 1997: Pruisne identified prions. 2002: Brenner and Hervitz studied genetic regulation of organ development and cell death. Other Discoveries Fanne Eilshemius Hesse (1850–1934), one of Koch's assistants, first proposed the use of agar in culture media. Richard Petri (1887) developed the Petri dish, a container used for solid culture media. Edward Jenner (1749–1823) was the first to prevent smallpox through vaccination. Alexander Flemming (1945) discovered penicillin from Penicillium notatum, which destroyed several pathogenic bacteria. Paul Erlich (1920) discovered the treatment for syphilis using arsenic. He studied toxins and antitoxins in quantitative terms, laying the foundation of biological standardization. Thanks for listening