Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 Chapter 1 The History and Scope of Microbiology

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2 The Importance of Microorganisms most populous group of organisms and are found everywhere on the planet play a major role in recycling essential elements source of nutrients and some carry out photosynthesis benefit society by their production of food, beverages, antibiotics and vitamins

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3 What is microbiology? study of organisms too small to be clearly seen by the unaided eye (i.e., microorganisms) these organisms are relatively simple in their construction and lack highly differentiated cells and distinct tissues

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 Members of the microbial world procaryotic cells lack a true membrane-delimited nucleus eucaryotic cells have a membrane- enclosed nucleus, are more complex morphologically and are usually larger than procaryotic cells

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5 Classification schemes five kingdom scheme includes Monera, Protista, Fungi, Animalia and Plantae with microbes placed in the first three kingdoms three domain alternative, based on a comparison of ribosomal RNA, divides microorganisms into Bacteria (true bacteria), Archaea and Eucarya (eucaryotes)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 6 Figure 1.1

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 7 Domain Bacteria – all procaryotic most are single-celled most have peptidoglycan in cell wall can survive broad range of environments most are non-pathogenic and play major role in nutrient recycling cyanobacteria produce oxygen as a result of photosynthesis

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 Domain Archaea – all procaryotic procaryotic distinguished from Bacteria by unique ribosomal RNA sequences lack peptidoglycan in cell wall many found in extreme environments no pathogenic species known

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 9 Domain Eucarya – all eucaryotic animals, plants and eucaryotic microorganisms –Microorganisms include protists (unicellular algae, protozoa, slime molds and water molds) and fungi –Most are larger than procaryotic cells

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10 Viruses acellular smallest of all microbes cause a range of diseases including some cancers (e.g. hepatitis B & C)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 11 Figure 1.2a

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 12 Figure 1.2b

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13 Figure 1.2c

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 14 Discovery of Microorganisms Antony van Leeuwenhoek ( ) –first person to observe and describe microorganisms accurately Figure 1.3 (a)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15 Figure 1.3 (b) and (c)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 16 The Conflict over Spontaneous Generation spontaneous generation –living organisms can develop from nonliving or decomposing matter Francesco Redi ( ) –disproved spontaneous generation for large animals –showed that maggots on decaying meat came from fly eggs

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 17 But could spontaneous generation be true for microorganisms? John Needham ( ) –his experiment: mutton broth in flasks  boiled  sealed –results: broth became cloudy and contained microorganisms Lazzaro Spallanzani ( ) –his experiment: water and seeds in flasks  sealed  placed in boiling water for 45 min –results: no growth of microorganisms

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 18 Louis Pasteur ( ) his experiments –filtered air through cotton : found objects resembling plant spores –placed nutrient solution in flasks –created flasks with long, curved necks –boiled the solutions –left flasks exposed to air results: no growth of microorganisms

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 19 Louis Pasteur ( ) Figure 1.5Figure 1.4

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 20 Final blow to theory of spontaneous generation John Tyndall ( ) –demonstrated that dust carries germs (microorganisms) –showed that if dust was absent, nutrient broths remained sterile, even if directly exposed to air –also provided evidence for the existence of exceptionally heat-resistant forms of bacteria (endospore)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 21 The role of microorganisms in disease was not immediately obvious establishing connection depended on development of techniques for studying microbes once established, led to study of host defenses - immunology

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 22 The golden age of microbiology ( ) Many disease producing organisms discovered Microbial metabolism studies undertaken Microbiological techniques refined A better understanding of the role of immunity and ways to control and prevent infection by microbes

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 23 Recognition of the relationship between microorganisms and disease Agostini Bassi ( ) –showed that a disease of silkworms was caused by a fungus

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 24 More evidences… M. J. Berkeley (ca. 1845) –demonstrated that the great Potato Blight of Ireland was caused by a water mold Heinrich de Bary (1853) –showed that smut and rust fungi caused cereal crop diseases Louis Pasteur –showed that the pébrine disease of silkworms was caused by a protozoan

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 25 Other evidences… Joseph Lister –provided indirect evidence that microorganisms were the causal agents of disease –developed a system of surgery designed to prevent microorganisms from entering wounds as well as methods for treating instruments and surgical dressings –his patients had fewer postoperative infections

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 26 Final proof… Robert Koch ( ) –established the relationship between Bacillus anthracis and anthrax –used criteria developed by his teacher Jacob Henle ( ) –these criteria now known as Koch’s postulates still used today to establish the link between a particular microorganism and a particular disease

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 27 Koch’s postulates The microorganism must be present in every case of the disease but absent from healthy individuals. The suspected microorganism must be isolated and grown in a pure culture. The same disease must result when the isolated microorganism is inoculated into a healthy host. The same microorganism must be isolated again from the diseased host.

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 29 The development of techniques for studying microbial pathogens Koch’s work led to discovery or development of: –agar –petri dish –nutrient broth and nutrient agar –methods for isolating microorganisms (streak plate method)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 30 Other developments… Charles Chamberland ( ) –developed porcelain bacterial filters used by Ivanoski and Beijerinck to study tobacco mosaic disease determined that extracts from diseased plants had infectious agents present which were smaller than bacteria and passed through the filters Infectious agents were eventually shown to be viruses

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 31 Immunological Studies Edward Jenner (ca. 1798) –used a vaccination procedure to protect individuals from smallpox * This work preceded the work establishing the role of microorganisms in disease

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 32 Other developments… Pasteur and Roux –discovered that incubation of cultures for long intervals between transfers caused pathogens to lose their ability to cause disease Pasteur and his coworkers –developed vaccines for chicken cholera, anthrax, and rabies

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 33 More developments… Emil von Behring ( ) and Shibasaburo Kitasato ( ) –developed antitoxins for diphtheria and tetanus –evidence for humoral immunity Elie Metchnikoff ( ) –discovered bacteria-engulfing phagocytic cells in the blood –evidence for cellular immunity

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 34 The Development of Industrial Microbiology and Microbial Ecology Louis Pasteur –demonstrated that alcohol fermentations and other fermentations were the result of microbial activity –developed the process of pasteurization to preserve wine during storage

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 35 Additional Developments… Sergei Winogradsky ( ) and Martinus Beijerinck ( ) –studied soil microorganisms and discovered numerous interesting metabolic processes (e.g., nitrogen fixation, chemolithotrophy) –pioneered the use of enrichment cultures and selective media

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 36 The Scope and Relevance of Microbiology importance of microorganisms –first living organisms on planet –live everywhere life is possible –more numerous than any other kind of organisms –global ecosystem depends on their activities –influence human society in many ways

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 37 Microbiology has basic and applied aspects Basic aspects are concerned with individual groups of microbes, microbial physiology, genetics, molecular biology and taxonomy Applied aspects are concerned with practical problems – disease, water, food and industrial microbiology

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 38 Microbiology actually represents many fields of study Examples –medical microbiology is concerned with diseases of humans and animals –immunology is concerned with how the immune system protects a host from pathogens

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 39 More fields… –microbial ecology is concerned with the relationship of organisms with their environment –microbial genetics and molecular biology are concerned with the understanding of how genetic information functions and regulates the development of cells and organisms

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 40 The Future of Microbiology: Challenges and opportunities for future microbiologists infectious disease new and improved industrial processes microbial diversity and microbial ecology –less than 1% of earth’s microbial population has been cultured

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 41 More challenges and opportunities… biofilms genome analysis microbes as model systems assessment of implications of new discoveries and technologies