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Chapter 1: The Microbial World & You. Learning Objectives Microbes in Our Lives 1-1List several ways in which microbes affect our lives.

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Presentation on theme: "Chapter 1: The Microbial World & You. Learning Objectives Microbes in Our Lives 1-1List several ways in which microbes affect our lives."— Presentation transcript:

1 Chapter 1: The Microbial World & You

2 Learning Objectives Microbes in Our Lives 1-1List several ways in which microbes affect our lives.

3 Microbes in Our Lives Microorganisms are organisms that are too small to be seen with the unaided eye Germ refers to a rapidly growing cell

4 Microbes in Our Lives A few are pathogenic (disease-causing) Decompose organic waste Are producers in the ecosystem by photosynthesis Produce industrial chemicals such as ethanol and acetone Produce fermented foods such as vinegar, cheese, and bread Produce products used in manufacturing (e.g., cellulase) and disease treatment (e.g., insulin)

5 Microbes in Our Lives Knowledge of microorganisms Allows humans to Prevent food spoilage Prevent disease occurrence Led to aseptic techniques to prevent contamination in medicine and in microbiology laboratories

6 Learning Objectives Naming and Classifying Microorganisms 1-2Recognize the system of scientific nomenclature that uses two names: a genus and a specific epithet. 1-3Differentiate the major characteristics of each group of microorganisms. 1-4List the three domains.

7 Naming and Classifying Microorganisms Linnaeus established the system of scientific nomenclature Each organism has two names: the genus and specific epithet

8 Scientific Names Are italicized or underlined The genus is capitalized; the specific epithet is lowercase Are Latinized and used worldwide May be descriptive or honor a scientist

9 Scientific Names After the first use, scientific names may be abbreviated with the first letter of the genus and the specific epithet: Escherichia coli and Staphylococcus aureus are found in the human body E. coli is found in the large intestine, and S. aureus is on skin

10 Types of Microorganisms Bacteria Archaea Fungi Protozoa Algae Viruses Multicellular animal parasites

11 Figure 1.1 Types of microorganisms. Bacteria Sporangia Prey Pseudopods CD4 + T cell HIVs

12 Bacteria Prokaryotes Peptidoglycan cell walls Binary fission For energy, use organic chemicals, inorganic chemicals, or photosynthesis

13 Bacteria Figure 1.1a Types of microorganisms. (a) The rod-shaped bacterium Haemophilus influenzae, one of the bacterial causes of pneumonia.

14 Archaea Prokaryotic Lack peptidoglycan Live in extreme environments Include: Methanogens Extreme halophiles Extreme thermophiles

15 Figure 4.5b Star-shaped and rectangular prokaryotes. Rectangular bacteria © 2013 Pearson Education, Inc.

16 Fungi Eukaryotes Chitin cell walls Use organic chemicals for energy Molds and mushrooms are multicellular, consisting of masses of mycelia, which are composed of filaments called hyphae Yeasts are unicellular

17 Figure 1.1b Types of microorganisms. Sporangia © 2013 Pearson Education, Inc. (b) Mucor, a common bread mold, is a type of fungus.

18 Protozoa Eukaryotes Absorb or ingest organic chemicals May be motile via pseudopods, cilia, or flagella

19 Prey Pseudopods © 2013 Pearson Education, Inc. Figure 1.1c Types of microorganisms. (c) An ameba, a protozoan, approaching a food particle.

20 Algae Eukaryotes Cellulose cell walls Use photosynthesis for energy Produce molecular oxygen and organic compounds

21 Figure 1.1d Types of microorganisms. © 2013 Pearson Education, Inc. (d) The pond alga Volvox.

22 Viruses Acellular Consist of DNA or RNA core Core is surrounded by a protein coat Coat may be enclosed in a lipid envelope Are replicated only when they are in a living host cell

23 Figure 1.1e Types of microorganisms. CD4 + T cell HIVs © 2013 Pearson Education, Inc. (e) Several human immunodeficiency viruses (HIVs), the causative agent of AIDS, budding from a CD4 + T cell.

24 Multicellular Animal Parasites Eukaryotes Multicellular animals Parasitic flatworms and roundworms are called helminths Microscopic stages in life cycles

25 Rod of Asclepius, symbol of the medical profession. A parasitic guinea worm (Dracunculus medinensis) is removed from the subcutaneous tissue of a patient by winding it onto a stick. This procedure may have been used for the design of the symbol in part (a). Figure 1.6 Parasitology: the study of protozoa and parasitic worms.

26 Classification of Microorganisms Three domains Bacteria Archaea Eukarya Protists Fungi Plants Animals

27 Figure 10.1 The Three-Domain System. Bacteria Mitochondria Cyanobacteria Chloroplasts Thermotoga Gram-positive bacteria Proteobacteria Horizontal gene transfer occurred within the community of early cells. Nucleoplasm grows larger Mitochondrion degenerates Giardia Euglenozoa Diatoms Dinoflagellates Ciliates Animals Fungi Amebae Slime molds Plants Green algae Eukarya Extreme halophiles Methanogens Hyperthermophiles Origin of chloroplasts Origin of mitochondria Archaea

28 The Germ Theory of Disease 1835: Agostino Bassi showed that a silkworm disease was caused by a fungus 1865: Pasteur believed that another silkworm disease was caused by a protozoan 1840s: Ignaz Semmelweis advocated handwashing to prevent transmission of puerperal fever from one obstetrical patient to another

29 The Germ Theory of Disease 1860s: Applying Pasteurs work showing microbes are in the air, can spoil food, and cause animal diseases, Joseph Lister used a chemical disinfectant to prevent surgical wound infections


31 The Germ Theory of Disease 1876: Robert Koch proved that a bacterium causes anthrax and provided the experimental steps, Kochs postulates, to prove that a specific microbe causes a specific disease


33 Vaccination 1796: Edward Jenner inoculated a person with cowpox virus, who was then protected from smallpox Vaccination is derived from vacca, for cow The protection is called immunity

34 The Birth of Modern Chemotherapy Treatment with chemicals is chemotherapy Chemotherapeutic agents used to treat infectious disease can be synthetic drugs or antibiotics Antibiotics are chemicals produced by bacteria and fungi that inhibit or kill other microbes

35 The First Synthetic Drugs Quinine from tree bark was long used to treat malaria Paul Ehrlich speculated about a magic bullet that could destroy a pathogen without harming the host 1910: Ehrlich developed a synthetic arsenic drug, salvarsan, to treat syphilis 1930s: sulfonamides were synthesized

36 A Fortunate AccidentAntibiotics 1928: Alexander Fleming discovered the first antibiotic Fleming observed that Penicillium fungus made an antibiotic, penicillin, that killed S. aureus 1940s: Penicillin was tested clinically and mass produced

37 Normal bacterial colony Area of inhibition of bacterial growth Penicillium colony Figure 1.5 The discovery of penicillin.

38 Modern Developments in Microbiology Bacteriology is the study of bacteria Mycology is the study of fungi Virology is the study of viruses Parasitology is the study of protozoa and parasitic worms

39 Modern Developments in Microbiology Immunology is the study of immunity Vaccines and interferons are being investigated to prevent and cure viral diseases The use of immunology to identify some bacteria according to serotypes was proposed by Rebecca Lancefield in 1933


41 Recombinant DNA Technology Microbial genetics: the study of how microbes inherit traits Molecular biology: the study of how DNA directs protein synthesis Genomics: the study of an organisms genes; has provided new tools for classifying microorganisms Recombinant DNA: DNA made from two different sources In the 1960s, Paul Berg inserted animal DNA into bacterial DNA, and the bacteria produced an animal protein

42 Recombinant DNA Technology 1941: George Beadle and Edward Tatum showed that genes encode a cells enzymes 1944: Oswald Avery, Colin MacLeod, and Maclyn McCarty showed that DNA is the hereditary material 1961: François Jacob and Jacques Monod discovered the role of mRNA in protein synthesis

43 Nobel Prizes for Microbiology Research * The first Nobel Prize in Physiology or Medicine 1901* von BeringDiphtheria antitoxin 1902 Ross Malaria transmission 1905 Koch TB bacterium 1908 Metchnikoff Phagocytes 1945 Fleming, Chain, Florey Penicillin 1952 Waksman Streptomycin 1969 Delbrück, Hershey, LuriaViral replication 1997 Prusiner Prions 2005Marshall & Warren H. pylori & ulcers 2008zur HausenHPV & cancer 2008Barré-Sinoussi & MontagnierHIV

44 Microbial Ecology Bacteria recycle carbon, nutrients, sulfur, and phosphorus that can be used by plants and animals

45 Bioremediation Bacteria degrade organic matter in sewage Bacteria degrade or detoxify pollutants such as oil and mercury

46 Figure 27.10 Composting municipal wastes. Solid municipal wastes being turned by a specially designed machine

47 Biological Insecticides Microbes that are pathogenic to insects are alternatives to chemical pesticides in preventing insect damage to agricultural crops and disease transmission Bacillus thuringiensis infections are fatal in many insects but harmless to other animals, including humans, and to plants

48 Biotechnology Biotechnology, the use of microbes to produce foods and chemicals, is centuries old

49 Figure 28.8 Making cheddar cheese. The milk has been coagulated by the action of rennin (forming curd) and is inoculated with ripening bacteria for flavor and acidity. Here the workers are cutting the curd into slabs. The curd is chopped into small cubes to facilitate efficient draining of whey. The curd is milled to allow even more drainage of whey and is compressed into blocks for extended ripening. The longer the ripening, the more acidic (sharper) the cheese.

50 Biotechnology Recombinant DNA technology, a new technique for biotechnology, enables bacteria and fungi to produce a variety of proteins, including vaccines and enzymes Missing or defective genes in human cells can be replaced in gene therapy Genetically modified bacteria are used to protect crops from insects and from freezing

51 Normal Microbiota Bacteria were once classified as plants, giving rise to use of the term flora for microbes This term has been replaced by microbiota Microbes normally present in and on the human body are called normal microbiota

52 Figure 1.7 Several types of bacteria found as part of the normal microbiota on the surface of the human tongue. © 2013 Pearson Education, Inc.

53 Normal Microbiota Normal microbiota prevent growth of pathogens Normal microbiota produce growth factors, such as folic acid and vitamin K Resistance is the ability of the body to ward off disease Resistance factors include skin, stomach acid, and antimicrobial chemicals

54 Biofilms Microbes attach to solid surfaces and grow into masses They will grow on rocks, pipes, teeth, and medical implants

55 Figure 1.8 Biofilm on a catheter. Staphylococcus

56 Infectious Diseases When a pathogen overcomes the hosts resistance, disease results Emerging infectious diseases (EIDs): new diseases and diseases increasing in incidence

57 Drug Resistance – The New Threat in Microbiology (i.e. MRSA) Methicillin-resistant Staphylococcus aureus 1950s: Penicillin resistance developed 1980s: Methicillin resistance 1990s: MRSA resistance to vancomycin reported VISA: vancomycin-intermediate-resistant S. aureus VRSA: vancomycin-resistant S. aureus

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