Unit 1 Part 1 Microbiology 2024 PDF

Microbiology Dr. Kevin Harris BSc., MSc., MBBS House Officer, Microbiology, GHPoS Unit 1 – Part I Introduction to Microbiology Learning Objectives ▪ General Introduction ▪ Fields of Microbiology ▪ The historical development of Microbiology ▪ Koch’s postulates What is Microbiology? Etymology ▪ from G...

Microbiology Dr. Kevin Harris BSc., MSc., MBBS House Officer, Microbiology, GHPoS Unit 1 – Part I Introduction to Microbiology Learning Objectives ▪ General Introduction ▪ Fields of Microbiology ▪ The historical development of Microbiology ▪ Koch’s postulates What is Microbiology? Etymology ▪ from Greek mikros ‘small’. ▪ from Greek bios ‘life’ ▪ from Greek logos ‘study of’. Put together ▪ The study of all living organisms that are too small to be visible with the naked eye. Who are these micro-organisms? ▪ Bacteria ▪ Archaea ▪ Viruses ▪ Fungi ▪ Prions ▪ Protozoa ▪ Algae More on classification later… What do they do? ▪ Anything ▪ Everything Where do we find them? ▪ EVERYWHERE!!!! The History of Microbiology First recordings ▪ Ancient Hebrew texts refer to “plagues” that beset the Pharaohs in Egypt more than 1,000BC ▪ The Greeks and Romans experienced major “plagues”. ▪ With each, enlightened observers noted resistance upon reexposure to the same disease process. ▪ The Greek historian Thucydides recorded such observations regarding smallpox. ▪ There is evidence that the Chinese exploited this knowledge in the sixteenth century in their practice of variolation. Fundamentals ▪ Fundamental principles of the scientific method were originally described by the Franciscan Monk Roger Bacon in 1269. Germ Theory ▪ Italian physician Girolamo Fracastoro (Fracastorius) had written a treatise on the germ theory of disease entitled “de Contagione” in 1546. ▪ Fracastorius surmised that tiny, free-living organisms, which he referred to as “seeds of disease,” existed in nature. ▪ Despite being invisible to human eyes, he postulated that these disease-causing organisms could be transmitted from person-to-person directly or via fomite intermediaries, thereby spreading contagion Reason? ▪ Microorganisms were neither proven, observed, nor correctly and accurately described until the 17th century. ▪ All these early studies lacked one thing… The Microscope! ▪ First person to report seeing microbes under the microscope. Robert Hooke – English Scientist ▪ 1665 - Hooke studied plant sections, particularly cork and saw a matrix of tiny cylindricallike structures. ▪ coined the term “Cell”. ▪ Researchers later discovered such structures in all types of living organisms but Hooke's naming remained. Antonie van Leeuwenhoek (1632–1723) ▪ A Dutch textile merchant and self-taught scientist credited with first identifying microorganisms, or “little animals,” using his newly developed microscope in 1677. ▪ Significance not fully appreciated until almost 200 years later when Pasteur and Koch first successfully cultured bacterial organisms from diseased tissues. Francesco Redi (1626-1697) – Italian Scientist ▪ Jar 1 – Left Open ▪ Jar 2 - Sealed ▪ Jar 3 – Covered with netting Redi’s Experiment ▪ Jar 1 – Maggots developed ▪ Flies were observed laying eggs on the meat in the open jar. ▪ Jar 2 – No Maggots developed ▪ Jar 3 - Maggots appeared on the netting ▪ Flies were observed laying eggs on the netting Spontaneous Generation Theory ▪ life forms can be generated from inanimate objects. ▪ Term was coined by Aristotle (383-322 BC.) ▪ Myths included maggots from rotting meat and mosquitoes from stagnant pond water. John Needham’s Rebuttal (1749) ▪ Spontaneous Generation Theory ▪ Placed a broth into a bottle, heated the bottle to kill anything inside, then sealed it. ▪ Days later, he reported the presence of life in the broth and announced that life had been created from non-life ▪ The truth? He did not heat it long enough to kill all the microbes. Lazzaro Spallanzani (1729–1799) – Italian Biologist ▪ Repeated Needham’s ▪ Rejected by spontaneous generation supporters ▪ Boiling altered broths so as to prevent spontaneous generation ▪ Absence of air prevented spontaneous generation Louis Pasteur (1822–1895) ▪ Disproved the Theory of Spontaneous Generation. ▪ Boiled meat broth in a flask, heated the neck of the flask in a flame until it became pliable, and bent it into the shape of an S. ▪ Result? NO MICROORGANISMS GREW. ▪ When Pasteur tilted the flask so that the broth reached the lowest point in the neck, where any airborne particles would have settled, the broth rapidly became cloudy with life. Louis Pasteur’s Experiment Ignaz Semmelweiss (1818–1865) ▪ The mortality rate for puerperal or “child bed” fever was 1 in 10. ▪ Death rate from puerperal fever in the physicians’ clinic decreased when the medical students were on vacation ▪ Showed washing hands with a dilute, chlorinated lime solution after autopsies removed the putrid odor ▪ In 1847, showed hand washing between patients reduced the mortality rate from puerperal fever by fourfold in 1 year Pioneers in the discovery of microorganisms. ▪ Robert Hooke (1635-1703) ▪ Antonie Van Leeuwenhoek (1632–1723) ▪ Lazzaro Spallanzani (1729–1799) ▪ Louis Pasteur (1822–1895) ▪ Robert Koch (1843–1910) Summary of History ▪ Hooke is credited as the first scientist to describe live processes under a microscope. ▪ Van Leeuwenhoek is largely credited with the discovery of microbes. ▪ Spallanzani and Pasteur performed several experiments to demonstrate that microbial life does not arise spontaneously. ▪ Koch conclusively showed that microbes can cause diseases. Germ Theory of Disease ▪ Koch’s studies, in combination with those of Pasteur’s, established this “germ theory” of disease. ▪ States that diseases are caused by minute infectious agents called germs/microorganisms. Robert Koch (1843–1910) ▪ Established that microbes can cause disease. ▪ Famous for isolating ▪ Bacillus anthracis (1877) ▪ Mycobacterium tuberculosis (1882) ▪ Vibrio cholerae (1883) ▪ Also famous for his development of Koch’s postulates. Koch’s Findings ▪ Koch studied anthrax - a disease of cattle ▪ Blood of cattle that were infected with anthrax always had large numbers of Bacillus anthracis. ▪ A small sample of blood from an infected animal is injected it into a healthy one, the healthy animal became sick. Koch’s Findings ▪ He also found that he could grow the bacteria in a nutrient broth, then inject it into a healthy animal, and cause illness. ▪ The infectious agent (Bacillus anthracis) could then be isolated from the newly infected animal in pure culture. ▪ This sequence of isolation, reinfection and recovery of the infectious agent is called Koch’s postulates. Koch’s Postulates 1. The microorganism must be found in in all organisms suffering from the disease, but should not be found in healthy organisms. 2. The microorganism must be isolated from a diseased organism and grown in pure culture. 3. The cultured microorganism should cause disease when introduced into a healthy organism. 4. The microorganism must be re-isolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent. Limitations? How is this relevant to you? ▪ Food & beverage ▪ Healthcare ▪ Biotech ▪ Environmental Sciences Food and beverage ▪ The first realization of the role of microorganisms was in 1837, with the discovery of the role of yeast in alcoholic fermentation. ▪ Lactic bacteria convert the unstable malic acid that is naturally present in wine into the stable lactic acid which gives the stability that is characteristic of high-quality wines that improve on storage. ▪ Lactobacillus species are used heavily in the dairy industry ▪ Meat starter cultures are used to make dried, fermented products such as salami, pepperoni, chorizo and dried ham. Food and beverage ▪ Many microorganisms carry out fermentation processes ▪ Yeasts ▪ Moulds ▪ Bacteria ▪ Fermentation involved in bread, beer, wine, vinegar, yogurt. Food and beverage ▪ Yeasts have a primary role in baking & alcohol. ▪ Baked goods like bread rise because of the presence of yeast as a raising agent. ▪ Yeasts feed on the sugars present in the bread dough, producing the gas carbon dioxide. Food and beverage ▪ Several different yeasts are used in brewing ▪ Beer ▪ ferment the sugars present in malted barley to produce alcohol. ▪ Winemaking ▪ ferments sugars in grape juice, with carbon dioxide as a byproduct. ▪ Sparkling wine is made by adding further yeast to the wine when it is bottled. The carbon dioxide formed in this second fermentation is trapped as bubbles. Healthcare & Biotech ▪ Antibiotics (1928). ▪ Produced in nature by molds such as Penicillium and bacteria such as Streptomyces and Bacillus. ▪ Vaccines ▪ The microbes that are the cause of infectious diseases are usually the ultimate source of vaccines. ▪ Monoclonal antibodies Healthcare ▪ Probiotic cultures have become popular in dairy products because of their health benefits. ▪ These cultures are all very carefully selected strains. Biotech ▪ genetic engineering of living organisms or their components to produce valuable products for various applications Biotech ▪ Oil spills ▪ Bacteria can break down oil to carbon dioxide and water. ▪ Not achieved by a single organism ▪ Vaccines ▪ Treatment of wastewater ▪ Biocontrol Biotech ▪ Agents of biological warfare ▪ In 1763 Lord Jeffrey Amherst, commander of British troops in North American during the French and Indian War used smallpox as a biological weapon against the hostile Native American forces in Pennsylvania. Fields of Applied Microbiology ▪ Public Health Microbiology: Concerns with monitoring, control and spread of diseases in communities. ▪ Biotechnology: Scientific manipulation of living organisms especially at molecular and genetic level to produce useful products. Fields of Applied Microbiology ▪ Industrial Microbiology: Concerned with industrial uses of microbes in production of alcoholic beverages, vitamins, NH2-acids, enzymes, antibiotics and other drugs. ▪ Agricultural Microbiology: Study of relationships of microbes and crops and on control of plant diseases and improvement of yields. ▪ Food Microbiology: Deals with interaction of microorganisms and food in relation to food’ processing, food spoilage, food borne disease and their prevention Fields of Applied Microbiology ▪ Dairy Microbiology: Deals with production and maintenance in quality control of dairy products. ▪ Aquatic Microbiology: Study of microorganisms found in fresh estuarine and marine waters. ▪ Air Microbiology: Deals with the role of aerospora in contamination and spoilage of food and dissemination of plant and animal diseases through air. Fields of Applied Microbiology ▪ Exomicrobiology: Deals with exploration for microbial life in outer space. ▪ Medical Microbiology: Causative agents of disease, diagnostic procedure for identification of causative agents, preventive measures. ▪ Immunology: Deals with the immune system that protects against infection and to study serology reactions. References ▪ Opal, S. M. (2010). A brief history of microbiology and immunology. In Vaccines: A biography (pp. 31-56). Springer, New York, NY. ▪ https://microbenotes.com/fields-of-microbiology/ (accessed 05-01-2023) That ends part 1 of today’s session!