Microbiology, The Science

1. Microbiology, The Science • The biology comes from bios referring to living organisms and logy means the study of, thus biology is the study of living organisms. • Micro means very small, viewed by microscope • Microbiology is the study of very small living organisms called microorganisms or microbes, these include bacteria, algea, protozoa, fungi and viruses. • Because many scientist do not consider viruses as living organisms, the terms infectious agents or infectious particles are often used in reference to viruses Dr. Adnan S. Jaran

2. A disease causing microorganisms called pathogens (3% of all known microbes) • The others are non pathogenic (97%), the beneficial microbes are 87% • Microbes live on and in our bodies e.g. skin, in the mouth and intestine are known as indigenous microflora (or indigenous microbiota). Some of them cause disease accidentally and known as opportunistic pathogens (10%) • Diseases caused by microbes are called infectious disease • Ubiquitous microbes means that they are virtually found every where in or on the body and in different environment of the globe Dr. Adnan S. Jaran

3. Many bacteria and fungi are Saprophytes, which aid in fertilization by returning inorganic nutrients to the soil. • Saprophytes break down dead and dying organic materials (plants and animals) into nitrates, phosphates, carbon dioxide, water and other chemicals necessary for plant growth • Saprophytes also destroy papers, feces and other biodegradable matters, although they cannot break down most plastics or glass • Nitrogen-fixing bacteria, that live in the root nodules of certain plants called legumes are able to return nitrogen from the air to the soil in the form of ammonia for use by other plants Dr. Adnan S. Jaran

4. Introduction to Microbiology The spread of certain diseases from one person to another long ago suggested the existence of invisible, transmissible agent of infection. Microscopic organisms (microbes) were not seen, however, until Antony Van Leeuwenhock (1632-1723) made microscopes with sufficient magnification, then after, the science of microbiology began. Dr. Adnan S. Jaran

5. Leeuwenhock observed motile microorganisms taken from a decayed tooth under the microscope. He observed major morphological classes of bacteria i.e. spheres, rods and spirals as well as large microbes i.e. protozoa, algae and yeast. In 1767 and after the convention of compound microscope, Linnaeus distinguished 6 species of microbes assigned to one class, and 600 types were figured in 1838. Dr. Adnan S. Jaran

6. Spontaneous Generation Until recent centuries it was widely believed that living organisms can arise spontaneously in decomposing organic matter. For visible organisms, this notion was dispelled in the 17th century. When Redi demonstrated that the appearance of maggots in decomposing meat depended on the deposition of eggs by flies. However, the idea of spontaneous generation persisted for the new world of microbes. Dr. Adnan S. Jaran

7. The answer for spontaneous generation has been shown by Spallanzani (1729-1799) who introduced the use of sterile culture media: he showed that an infusion of meat would remain clear indefinitely if boiled and properly sealed. Moreover, in 1837 Schwann showed that hot air passed through tubes and enter the boiled flask will not decompose the meat infusion. Pasteur in 19th century demonstrated that meat infusion remain clear if it kept far from air-dust and live germs. Since then, the spontaneous generation notion no more accepted. Dr. Adnan S. Jaran

8. Problem of Spores * Pasteur succeeded because he used sugar and yeast extract as infusion. Others used hay infusion and they never reached clear infusion after boiling. British physicist John Tyndall, brought a bale of hay to his laboratory and after then he could no longer achieve sterility, in the same room by boiling. Tyndall concluded that the hay had contaminated his laboratory with incredible kind of living organisms: one that could survive boiling. Dr. Adnan S. Jaran

9. In the same year, 1877, Ferdinand Cohn demonstrated that resistant forms as small, refractile endospores as showed that they where stages in the life cycle of the hay bacillus (Bacillus Subtilis). Then after, autoclaving (Sterilization by heat (120oC) & moisture under pressure) showed to be killing spores. Dr. Adnan S. Jaran

10. In 20th century, biological studies of microbes showed that there are different kinds of microbes, which found in different ecological niches and have different actions, Microbiology then developed into there groups: microbes responsible for; fermentation, for diseases in man, animals and plants, and for the cycle of organic matter in the nature. These developments gave rise to applied fields of industrial, medical microbiology. and agricultural Dr. Adnan S. Jaran

11. The Role Of Microbes In Fermentation • The study of fermentation came early and start by use of fermentation in preserving food through accumulation of lactic acid (soured milk, cheese and silage). • In 1830s, Schwann & others showed that microbes are responsible for alcoholic fermentation by using grape juice. In 1857, Pasteur showed that different kinds of microbes are associated with different kinds of fermentation (yeast in alcoholic fermentation and small rods (lactobacilli) in lactic acid fermentation). Dr. Adnan S. Jaran

12. Fermentation refers to the microbial decomposition of vegetable matters which contains mostly carbohydrates, while putrefaction refers to the formation of more unpleasant products by the decomposition of high protein materials, such as meat and eggs. • Pasteur on his studies on microbial fermentation, developed the study of microbial metabolism or microbial physiology. In particular, Pasteur showed that life is possible without air, that some organisms (obligatory anaerobic) are even inhibited by air. Dr. Adnan S. Jaran

13. Selective Cultivation By study fermentation, investigators showed that type of substrate (media) affect growth of different microbes. In alcoholic fermentation using grape juice (high sugar concentration and low protein contents) lead to a condition now known as low pH, that favors the out-growth of acid-resistant yeasts and thus yields an alcoholic fermentation. In contrast, in milk neutralizing of acid by high protein contents favors the out-growth of faster-growing but more sensitive, which cause a lactic acid-fermentation. Contamination of the starting inoculum will affect the fermentation process and then the end-products. Dr. Adnan S. Jaran

14. Microbiology and Medicine • The germ theory of disease: The contagious diseases are transmitted or spread by seeds (microbes) either directly or indirectly (transmitted from diseased to healthy person). Dr. Adnan S. Jaran

15. Transmission of Infection • Demonstrated in 18th century by John Hunter, who inoculated himself with pus-material from a patient with gonorrhea (experimental animal was not used until 20 years later) and used for transmission of the tuberculosis causative agent (direct & indirect). • The indirect transmission of disease was recognized later in 1840s, physician move with unwashed hands between patients in hospitals lead to puerperal sepsis and cause of maternal death. In London, John Snow showed that cholera agent is spread through contaminated water with fecal matters. Dr. Adnan S. Jaran

16. Recognition of Microbes as agents of Infection • In 1836, Agostin Bassi showed that fungi cause of a disease of silk worms and 3 years later Schönlein discovered the association of fungus with human skin disease (favus). • The etiological role of bacteria in anthrax was established by Robert Koch in1867 confirmed by Pasteur and his colleagues. Dr. Adnan S. Jaran

17. Koch then isolated anthrax-bacillus in pure culture and showed that culture could transmit the disease to mice. Also Koch identified tubercle bacilli and introduced his postulates for distinguishing a pathogenic from adventitious microbes: • 1- The microbe is regularly found in the lesions of the disease. • 2- It can be isolated in a pure culture on artificial media. • 3- Inoculation of this culture produces a similar disease in experimental animals. • 4- The microbes can be recovered from the lesions in these animals. Dr. Adnan S. Jaran

18. In 1879, Albert Neisser discovered that the disease gonorrhea is caused by Neisseria gonorrhea. In 1892, Dimitri Ivanovisky discovered a virus called Tobacco Mozaic virus. • In 1910, Howard Rickets discovered an organism called Rickettsia caused a disease named Typhus. • In 1798, Edward Jenner used cowpox virus as a vaccine to protect people from smallpox. Edward Gaffky discovered that salmonella typhi cause Typhoid fever. Dr. Adnan S. Jaran

19. Leofler discovered that diphtheria is caused by Corynebacterium diphtheriae. • Ketasato discovered that the disease tetanus is caused by Clostridium tetani. Dr. Adnan S. Jaran

20. Microbiology Branches Basic Microbiology: 1. Deal with all microorganisms. 2. Classification of microorganisms. 3. Visualization of microorganisms (microscopes & staining). 4. Metabolism and metabolic pathways. 5. Nutrition, growth and its requirements. 6. Techniques of sterilization & the disinfection. Dr. Adnan S. Jaran

21. Medical Microbiology 1. Is the study of organisms that cause diseases to humans (pathogenic organisms). 2. The relationship between microorganism and the disease, e.g. S. typhi cause typhoid fever. 3. Characteristics of microorganism causing disease, and how microorganism cause disease as invasion of tissue or by producing toxic products. 4. Mechanism of disease establishment called Pathogenesis. Dr. Adnan S. Jaran

22. 5. Virulence factor of the microorganism called Pathogenicity, e.g. ability to invade host tissue, production of toxins as by-products. 6. Epidemiology of the disease, deal with source of the disease and method of spread. 7. Diagnosis of disease, based on: 8. Proper sampling. 9. Stain and culturing. Dr. Adnan S. Jaran

23. 10. Recovery of pathogenic organism. 11. Treatment of the disease by antimicrobial agents, e.g. antibiotics. 12. Prevention of infection: by vaccination & quarantine. 13. Control of infection: by isolation of human or animal, and by proper treatment. Food Microbiology: 1. Microorganism (M.O.) used in food processing and ripening are not pathogenic. Dr. Adnan S. Jaran

24. 2. M.O. can cause food infection & poisoned food, e.g. Staphylococcus aureus. 3. M.O. can cause Spoilage of food. 4. Preservation of food: drying, salting, freezing, jamming, canning & use of preservatives (chemicals such as sodium benzoate & sodium nitrite). The method of preservation must be suitable for the food type and must retain food quality and prevent its destruction by M.O. Dr. Adnan S. Jaran

25. Industrial Microbiology: 1. Deal with M.O. used in the industry. 2. Characteristics of the bacterial strains. 3. Maintain the bacterial strains unchanged. 4. Concern with quality of the products & its quantity. 5. Deal with storage condition of the products. 6. Shelf-life of the products: for how long the material will be stored under proper condition without being destructed or spoiled. 7. Mostly industrial microbiology use fermentation process to produce certain product. Dr. Adnan S. Jaran

26. Pharmaceutical Microbiology: 1. It’s the use of M.O. in the production of pharmaceutical products such as antibiotics, alcohols, enzymes and vitamins. 2. Deal with check of contamination and spoilage of pharmaceutical preparation by adding preservative. 3. Use different sterilization techniques and preservation of pharmaceutical products. 4. Proper use of antibiotic and chemotherapeutic agent (give proper type of antibiotic in proper time for proper organism in proper dose for proper duration). Dr. Adnan S. Jaran

27. Agricultural Microbiology: 1. Deal with the N (nitrogen), C (carbon) and S (sulfur) cycle in nature. 2. Fertility of soil. 3. Disease of plants. 4. M.O. in ruminants used for digestion in the rumen. Dr. Adnan S. Jaran

28. Sanitary Microbiology: 1. Deal with proper disposal of sewage and garbage. 2. Disposal of waste and wastewater. 3. Safety of water and food. 4. Control of flies and vectors, e.g. mosquitoes. Microbial physiology and genetics: 1. Research in microbial physiology lead to better understanding of the functions of microbes 2. DNA structure and genetic manipulation with virus and bacteria Dr. Adnan S. Jaran

29. Environmental microbiology (microbial ecology): • It becomes important branch because the concern about pollution of soil, air, water, sewage, food and dairy products • Also cycling of elements by microbial, environmental and geochemical processes • In addition, the biodegradation of toxic chemicals by various microorganisms is being used as method for cleaning up hazardous materials found in soil and water Dr. Adnan S. Jaran