Chapter 1. Microbes in Our Lives. Microbes in Our Lives. Microbes in Our Lives

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1 1 Microbes in Our Lives 2 Chapter 1 The Microbial World and You Microorganisms are organisms that are too small to be seen with the unaided eye Germ refers to a rapidly growing cell Lectures prepared by Christine L. Case Copyright Lectures prepared by Christine L. Case Microbes in Our Lives 3 Microbes in Our Lives 4 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) 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

2 Naming and Classifying Microorganisms 5 Naming and Classifying Microorganisms 6 Learning Objectives 1-2 Recognize the system of scientific nomenclature that uses two names: a genus and a specific epithet. 1-3 Differentiate the major characteristics of each group of microorganisms. 1-4 List the three domains. Linnaeus established the system of scientific nomenclature Each organism has two names: the genus and specific epithet Scientific Names 7 Escherichia coli 8 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 Honors the discoverer, Theodor Escherich Describes the bacterium s habitat the large intestine, or colon

3 Staphylococcus aureus 9 Scientific Names 10 Describes the clustered (staphylo-) spherical (cocci) cells Describes the gold-colored (aureus) colonies 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 Scientific Names 11 Types of Microorganisms 12 Which is a correct scientific name? Bacteria a. Baker s yeast b. Saccharomyces cerevisiae c. Saccharomyces cerevisiae d. S. cerevisiae Archaea Fungi Protozoa Algae Viruses Multicellular animal parasites

4 Figure 1.1 Types of microorganisms. 13 Bacteria 14 Bacteria Sporangia Prey Pseudopods Prokaryotes Peptidoglycan cell walls Binary fission For energy, use organic chemicals, inorganic chemicals, or photosynthesis CD4 + T cell HIVs Figure 1.1a Types of microorganisms. 15 Archaea 16 Bacteria Prokaryotic Lack peptidoglycan Live in extreme environments Include: Methanogens Extreme halophiles Extreme thermophiles (a) The rod-shaped bacterium Haemophilus influenzae, one of the bacterial causes of pneumonia.

5 Fungi 17 Figure 1.1b Types of microorganisms. 18 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 Sporangia (b) Mucor, a common bread mold, is a type of fungus. Protozoa 19 Figure 1.1c Types of microorganisms. 20 Eukaryotes Absorb or ingest organic chemicals May be motile via pseudopods, cilia, or flagella Prey Pseudopods (c) An ameba, a protozoan, approaching a food particle.

6 Algae 21 Figure 1.1d Types of microorganisms. 22 Eukaryotes Cellulose cell walls Use photosynthesis for energy Produce molecular oxygen and organic compounds (d) The pond alga Volvox. Viruses Acellular: are not cells, are not living 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 24 (e) Several human immunodeficiency viruses (HIVs), the causative agent of AIDS, budding from a CD4 + T cell.

7 Multicellular Animal Parasites 25 Figure 1.6 Parasitology: the study of protozoa and parasitic worms. 26 Eukaryotes Multicellular animals Parasitic flatworms and roundworms are called helminths Microscopic stages in life cycles 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). Classification of Microorganisms 27 Figure 10.1 The Three-Domain System. 28 Eukarya Three domains Bacteria Archaea Eukarya Protists Fungi Plants Animals Proteobacteria Mitochondria Gram-positive bacteria Bacteria Thermotoga Cyanobacteria Chloroplasts Origin of mitochondria Origin of chloroplasts Archaea Methanogens Hyperthermophiles Extreme halophiles Amebae Slime molds Plants Green algae Fungi Giardia Animals Diatoms Euglenozoa Ciliates Dinoflagellates Horizontal gene transfer occurred within the community of early cells. Mitochondrion degenerates Nucleoplasm grows larger

8 A Brief History of Microbiology 29 The First Observations 30 Ancestors of bacteria were the first life on Earth The first microbes were observed in : Robert Hooke reported that living things are composed of little boxes, or cells 1858: Rudolf Virchow said cells arise from preexisting cells Cell theory: All living things are composed of cells and come from preexisting cells The First Observations 31 Figure 1.2b Anton van Leeuwenhoek s microscopic observations : Anton van Leeuwenhoek described live microorganisms Lens Location of specimen on pin Specimen-positioning screw Focusing control Stage-positioning screw Microscope replica

9 The Debate over Spontaneous Generation Spontaneous generation: the hypothesis that living organisms arise from nonliving matter; a vital force forms life Biogenesis: the hypothesis that living organisms arise from preexisting life 33 Evidence Pro and Con 1668: Francesco Redi filled 6 jars with decaying meat Conditions Three jars covered with fine net Three open jars Results No maggots Maggots appeared 34 From where did the maggots come? What was the purpose of the sealed jars? Spontaneous generation or biogenesis? Evidence Pro and Con 35 Evidence Pro and Con : John Needham put boiled nutrient broth into covered flasks 1765: Lazzaro Spallanzani boiled nutrient solutions in flasks Conditions Results Conditions Results Nutrient broth heated, then placed in sealed flask Microbial growth Nutrient broth placed in flask, heated, then sealed No microbial growth From where did the microbes come? Spontaneous generation or biogenesis? Spontaneous generation or biogenesis?

10 Evidence Pro and Con 37 The Theory of Biogenesis : Louis Pasteur demonstrated that microorganisms are present in the air Conditions Results Pasteur s S-shaped flask kept microbes out but let air in This was a control experiment that allowed the vital force access to the broth Nutrient broth placed in flask, heated, NOT sealed Nutrient broth placed in flask, heated, then sealed Microbial growth No microbial growth Spontaneous generation or biogenesis? Figure 1.3 Disproving the Theory of Spontaneous Generation. Pasteur first poured beef broth into a long-necked flask. Next he heated the neck of the flask and bent it into an S-shape; then he boiled the broth for several minutes. 39 Microorganisms did not appear in the cooled solution, even after long periods. Bend prevented microbes from entering the flask. The Golden Age of Microbiology Beginning with Pasteur s work, discoveries included the relationship between microbes and disease, immunity, and antimicrobial drugs 40 Microorganisms were present in the broth. Microorganisms were not present in the broth after boiling. Microorganisms were not present even after long periods.

11 Fermentation and Pasteurization 41 Fermentation and Pasteurization 42 Pasteur showed that microbes are responsible for fermentation Fermentation is the conversion of sugar to alcohol to make beer and wine Microbial growth is also responsible for spoilage of food Bacteria that use alcohol and produce acetic acid spoil wine by turning it to vinegar (acetic acid) Pasteur demonstrated that these spoilage bacteria could be killed by heat that was not hot enough to evaporate the alcohol in wine Pasteurization is the application of a high heat for a short time 43 The Germ Theory of Disease : 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

12 The Germ Theory of Disease s: Applying Pasteur s 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 The Germ Theory of Disease : Robert Koch proved that a bacterium causes anthrax and provided the experimental steps, Koch s postulates, to prove that a specific microbe causes a specific disease

13 Vaccination 49 The Birth of Modern Chemotherapy : 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 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 The First Synthetic Drugs 51 A Fortunate Accident Antibiotics 52 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 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

14 Figure 1.5 The discovery of penicillin. 53 Modern Developments in Microbiology 54 Normal bacterial colony Area of inhibition of bacterial growth 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 Penicillium colony 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

15 Recombinant DNA Technology 57 Recombinant DNA Technology 58 Microbial genetics: the study of how microbes inherit traits Molecular biology: the study of how DNA directs protein synthesis Genomics: the study of an organism s 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 1941: George Beadle and Edward Tatum showed that genes encode a cell s 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 Nobel Prizes for Microbiology Research 59 Microbial Ecology 60 * The first Nobel Prize in Physiology or Medicine 1901* von Bering Diphtheria antitoxin 1902 Ross Malaria transmission 1905 Koch TB bacterium 1908 Metchnikoff Phagocytes 1945 Fleming, Chain, Florey Penicillin 1952 Waksman Streptomycin 1969 Delbrück, Hershey, Luria Viral replication 1997 Prusiner Prions 2005 Marshall & Warren H. pylori & ulcers 2008 zur Hausen HPV & cancer 2008 Barré-Sinoussi & Montagnier HIV Bacteria recycle carbon, nutrients, sulfur, and phosphorus that can be used by plants and animals

16 Bioremediation 61 Figure Composting municipal wastes. 62 Bacteria degrade organic matter in sewage Bacteria degrade or detoxify pollutants such as oil and mercury Solid municipal wastes being turned by a specially designed machine Biological Insecticides 63 Figure 11.15a Bacillus. 64 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 Insert Fig 11.15a (a) Bacillus thuringiensis. The diamond-shaped crystals shown next to the endospore are toxic to insects that ingest them. This electron micrograph was made using the technique of shadow casting described on page 62.

17 Biotechnology 65 Figure 28.8 Making cheddar cheese. 66 Biotechnology, the use of microbes to produce foods and chemicals, is centuries old 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. Applications of Microbiology, unnumbered figure, page Biotechnology 68 Xanthan 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 Xanthomonas campestris producing gooey xanthan.

18 Normal Microbiota 69 Figure 1.7 Several types of bacteria found as part of the normal microbiota on the surface of the human tongue. 70 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 Normal Microbiota 71 Biofilms 72 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 Microbes attach to solid surfaces and grow into masses They will grow on rocks, pipes, teeth, and medical implants

19 Figure 1.8 Biofilm on a catheter. Staphylococcus 73 Infectious Diseases 74 When a pathogen overcomes the host s resistance, disease results Emerging infectious diseases (EIDs): new diseases and diseases increasing in incidence Avian Influenza A 75 Figure 13.3b Morphology of an enveloped helical virus. 76 Influenza A virus Primarily in waterfowl and poultry Sustained human-to-human transmission has not occurred yet

20 MRSA 77 West Nile Encephalitis 78 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 Caused by West Nile virus First diagnosed in the West Nile region of Uganda in 1937 Appeared in New York City in 1999 In nonmigratory birds in 47 states Disease in Focus 22.2 Types of Arboviral Encephalitis, unnumbered figure. 79 Bovine Spongiform Encephalopathy 80 Caused by a prion Also causes Creutzfeldt-Jakob disease (CJD) New variant CJD in humans is related to cattle that have been fed sheep offal for protein Culex mosquito engorged with human blood.

21 Figure 22.18b Spongiform encephalopathies. 81 Escherichia coli O157:H7 82 Toxin-producing strain of E. coli First seen in 1982 Leading cause of diarrhea worldwide Holes Insert Fig 22.18b Ebola Hemorrhagic Fever 83 Figure Ebola hemorrhagic virus. 84 Ebola virus Causes fever, hemorrhaging, and blood clotting First identified near Ebola River, Congo Outbreaks every few years

22 Cryptosporidiosis 85 Figure Cryptosporidiosis. 86 Cryptosporidium protozoa First reported in 1976 Causes 30% of diarrheal illness in developing countries In the United States, transmitted via water Intestinal mucosa Oocyst Acquired immunodeficiency syndrome (AIDS) 87 Caused by human immunodeficiency virus (HIV) First identified in 1981 Worldwide epidemic infecting 33 million people; 7500 new infections every day Sexually transmitted infection affecting males and females HIV/AIDS in the United States: 26% are female, and 49% are African American