The Microbial World and You 1 The Microbial World and You

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

Microbes in Our Lives Microorganisms are organisms that are too small to be seen with the unaided eye Microbes include bacteria, fungi, protozoa, microscopic algae, and viruses

Microbes in Our Lives A few are pathogenic (disease-producing) Decompose organic waste Generate oxygen by photosynthesis Produce chemical products such as ethanol, acetone, and vitamins Produce fermented foods such as vinegar, cheese, and bread Produce products used in manufacturing (e.g., cellulase) and disease treatment (e.g., insulin)

Designer Jeans: Made by Microbes? Denim fading: Trichoderma Cotton production: Gluconacetobacter Bleaching: mushroom peroxidase Indigo: Escherichia coli Plastic: bacterial polyhydroxyalkanoate

Applications of Microbiology 1.1

Applications of Microbiology 1.2

Microbes in Our Lives Knowledge of microorganisms allows humans to Prevent food spoilage Prevent disease Understand causes and transmission of disease to prevent epidemics

Check Your Understanding Describe some of the destructive and beneficial actions of microbes. 1-1

Naming and Classifying Microorganisms 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.

Naming and Classifying Microorganisms Carolus Linnaeus established the system of scientific nomenclature in 1735 Each organism has two names: the genus and the specific epithet

Nomenclature 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

Nomenclature Escherichia coli Honors the discoverer, Theodor Escherich Describes the bacterium's habitat—the large intestine, or colon

Nomenclature Staphylococcus aureus Describes the clustered (staphylo-) spherical (coccus) cells Describes the gold-colored (aureus) colonies

Nomenclature 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

Check Your Understanding Distinguish a genus from a specific epithet. 1-2

Types of Microorganisms Bacteria Archaea Fungi Protozoa Algae Viruses Multicellular Animal Parasites

Figure 1.1 Types of microorganisms. Bacteria Sporangia Food particle Pseudopod CD4 + T cell HIVs

Bacteria Prokaryotes Single-celled Peptidoglycan cell walls ”Prenucleus" Single-celled Peptidoglycan cell walls Divide via binary fission Derive nutrition from organic or inorganic chemicals or photosynthesis

Figure 1.1a Types of microorganisms. Bacteria

Archaea Prokaryotes Lack peptidoglycan cell walls Often live in extreme environments Include: Methanogens Extreme halophiles Extreme thermophiles

Fungi Eukaryotes Chitin cell walls Absorb organic chemicals for energy Distinct nucleus Chitin cell walls Absorb organic chemicals for energy Yeasts are unicellular Molds and mushrooms are multicellular Molds consist of masses of mycelia, which are composed of filaments called hyphae

Figure 1.1b Types of microorganisms. Sporangia

Protozoa Eukaryotes Absorb or ingest organic chemicals May be motile via pseudopods, cilia, or flagella Free-living or parasitic (derive nutrients from a living host)

Figure 1.1c Types of microorganisms. Food particle Pseudopod

Algae Eukaryotes Cellulose cell walls Found in freshwater, saltwater, and soil Use photosynthesis for energy Produce oxygen and carbohydrates

Figure 1.1d Types of microorganisms.

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 Inert outside living hosts

Figure 1.1e Types of microorganisms. CD4 + T cell HIVs

Multicellular Animal Parasites Eukaryotes Multicellular animals Not strictly microorganisms Parasitic flatworms and roundworms are called helminths Some microscopic stages in their life cycles

Check Your Understanding Which groups of microbes are prokaryotes? Which are eukaryotes? 1-3

Classification of Microorganisms Developed by Carl Woese Three domains based on cellular organization Bacteria Archaea Eukarya Protists Fungi Plants Animals

Figure 10.1 Three-Domain System.

Check Your Understanding What are the three domains? 1-4

A Brief History of Microbiology Learning Objectives 1-5 Explain the importance of observations made by Hooke and van Leeuwenhoek. 1-6 Compare spontaneous generation and biogenesis. 1-7 Identify the contributions to microbiology made by Needham, Spallanzani, Virchow, and Pasteur.

The First Observations 1665: Robert Hooke reported that living things are composed of little boxes, or "cells" Marked the beginning of cell theory: All living things are composed of cells The first microbes were observed from 1623–1673 by Anton van Leeuwenhoek "Animalcules" viewed through magnifying lenses

Figure 1.2b Anton van Leeuwenhoek's microscopic observations. Lens Location of specimen on pin Specimen- positioning screw Focusing control Stage- positioning screw Microscope replica

Check Your Understanding What is the cell theory? 1-5

The Debate over Spontaneous Generation Spontaneous generation: the hypothesis that life arises from nonliving matter; a "vital force" is necessary for life Biogenesis: the hypothesis that living cells arise only from preexisting living cells

The Debate over Spontaneous Generation 1668: Francesco Redi filled jars with decaying meat Conditions Results Jars covered with fine net No maggots Open jars Maggots appeared Sealed jars From where did the maggots come? What was the purpose of the sealed jars? Spontaneous generation or biogenesis?

The Debate over Spontaneous Generation 1745: John Needham put boiled nutrient broth into covered flasks Conditions Results Nutrient broth heated, then placed in covered flask Microbial growth From where did the microbes come? Spontaneous generation or biogenesis?

The Debate over Spontaneous Generation 1765: Lazzaro Spallanzani boiled nutrient solutions in sealed flasks Conditions Results Nutrient broth placed in flask, sealed, then heated No microbial growth Spontaneous generation or biogenesis?

The Theory of Biogenesis 1858: Rudolf Virchow said cells arise from preexisting cells

The Theory of Biogenesis 1861: Louis Pasteur demonstrated that microorganisms are present in the air Conditions Results Nutrient broth placed in flask, heated, NOT sealed Microbial growth Nutrient broth placed in flask, heated, then immediately sealed No microbial growth Spontaneous generation or biogenesis?

The Theory of Biogenesis Pasteur also used S-shaped flasks Keep microbes out but let air in Broth in flasks showed no signs of life Neck of flask traps microbes Microorganisms originate in air or fluids, not mystical forces

Figure 1.3 Disproving the Theory of Spontaneous Generation.

Check Your Understanding What evidence supported spontaneous generation? 1-6 How was spontaneous generation disproved? 1-7

A Brief History of Microbiology Learning Objectives 1-8 Explain how Pasteur's work influenced Lister and Koch. 1-9 Identify the importance of Koch's postulates. 1-10 Identify the importance of Jenner's work. 1-11 Identify the contributions to microbiology made by Ehrlich and Fleming.

The Golden Age of Microbiology 1857–1914 Beginning with Pasteur's work, discoveries included the relationship between microbes and disease, immunity, and antimicrobial drugs

The Golden Age of Microbiology Pasteur showed that microbes are responsible for fermentation Fermentation is the microbial conversion of sugar to alcohol in the absence of air Microbial growth is also responsible for spoilage of food and beverages Bacteria that use air spoil wine by turning it to vinegar (acetic acid)

The Golden Age of Microbiology 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 to kill harmful bacteria in beverages

Figure 1.4 Milestones in the Golden Age of Microbiology (1 of 3).

The Germ Theory of Disease 1835: Agostino Bassi showed that a silkworm disease was caused by a fungus 1865: Pasteur showed 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

The Germ Theory of Disease 1860s: Applying Pasteur's work showing that microbes are in the air, can spoil food, and cause animal diseases, Joseph Lister used a chemical antiseptic (phenol) to prevent surgical wound infections

Figure 1.4 Milestones in the Golden Age of Microbiology (2 of 3).

The Germ Theory of Disease 1876: Robert Koch discovered that a bacterium causes anthrax and provided the experimental steps, Koch's postulates, to demonstrate that a specific microbe causes a specific disease

Figure 1.4 Milestones in the Golden Age of Microbiology (3 of 3).

Vaccination 1796: Edward Jenner inoculated a person with cowpox virus, who was then immune from smallpox Vaccination is derived from the Latin word vacca, meaning cow The protection is called immunity

Check Your Understanding Summarize in your own words the germ theory of disease. 1-8 What is the importance of Koch's postulates? 1-9 What is the significance of Jenner's discovery? 1-10

The Birth of Modern Chemotherapy: Dreams of a "Magic Bullet" Treatment of disease with chemicals is called 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 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

A Fortunate Accident—Antibiotics 1928: Alexander Fleming discovered the first antibiotic (by accident) Fleming observed that Penicillium fungus made an antibiotic, penicillin, that killed S. aureus 1940s: Penicillin was tested clinically and mass-produced

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

Check Your Understanding What was Ehrlich's "magic bullet"? 1-11

Modern Developments in Microbiology Learning Objectives 1-12 Define bacteriology, mycology, parasitology, immunology, and virology. 1-13 Explain the importance of microbial genetics and molecular biology.

Bacteriology, Mycology, and Parasitology Bacteriology is the study of bacteria Mycology is the study of fungi Parasitology is the study of protozoa and parasitic worms

Figure 1.6 Parasitology: the study of protozoa and parasitic worms.

Immunology Immunology is the study of immunity Vaccines and interferons are used to prevent and cure viral diseases A major advance in immunology occurred in 1933 when Rebecca Lancefield classified streptococci based on their cell wall components

Figure 1.7 Rebecca Lancefield (1895–1981), who discovered differences in the chemical composition of a polysaccharide in the cell walls of many pathogenic streptococci.

Virology Virology is the study of viruses Dmitri Iwanowski in 1892 and Wendell Stanley in 1935 discovered the cause of mosaic disease of tobacco as a virus Electron microscopes have made it possible to study the structure of viruses in detail

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 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

Recombinant DNA Technology 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 1953: James Watson and Francis Crick proposed a model of DNA structure 1961: François Jacob and Jacques Monod discovered the role of mRNA in protein synthesis

Figure 1.4 Milestones in the Golden Age of Microbiology.

Check Your Understanding Define bacteriology, mycology, parasitology, immunology, and virology. 1-12 Differentiate microbial genetics from molecular biology. 1-13

Microbes and Human Welfare Learning Objectives 1-14 List at least four beneficial activities of microorganisms. 1-15 Name two examples of biotechnology that use recombinant DNA technology and two examples that do not.

Recycling Vital Elements Microbial ecology is the study of the relationship between microorganisms and their environment Bacteria convert carbon, oxygen, nitrogen, sulfur, and phosphorus into forms used by plants and animals

Bioremediation: Using Microbes to Clean Up Pollutants Bacteria degrade organic matter in sewage Bacteria degrade or detoxify pollutants such as oil and mercury

Figure 27.8 Composting municipal wastes.

Insect Pest Control by Microorganisms Microbes that are pathogenic to insects are alternatives to chemical pesticides Prevent insect damage to agricultural crops and disease transmission Bacillus thuringiensis infections are fatal in many insects but harmless to animals and plants

Bacillus thuringiensis. The diamond-shaped Figure 11.21 Bacillus. Endospore Collapsed B. thuringiensis Toxic crystal 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.

Modern Biotechnology and Recombinant DNA Technology Biotechnology is the use of microbes for practical applications, such as producing foods and chemicals Recombinant DNA technology enables bacteria and fungi to produce a variety of proteins, 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

Check Your Understanding Name two beneficial uses of bacteria. 1-14 Differentiate biotechnology from recombinant DNA technology. 1-15

Microbes and Human Disease Learning Objectives 1-16 Define normal microbiota and resistance. 1-17 Define biofilm. 1-18 Define emerging infectious disease.

Normal Microbiota Bacteria were once classified as plants, giving rise to 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

Figure 1.8 Several types of bacteria found as part of the normal microbiota on the surface of the human tongue.

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

Biofilms Microbes attach to solid surfaces and grow into masses They will grow on rocks, pipes, teeth, and medical implants Biofilms can cause infections and are often resistant to antibiotics

Figure 1.9 Biofilm on a catheter. Staphylococcus

Emerging Infectious Diseases When a pathogen invades a host and overcomes the host's resistance, disease results Emerging infectious diseases (EIDs): new diseases and diseases increasing in incidence

Emerging Infectious Diseases Middle East respiratory syndrome (MERS) Caused by Middle East respiratory syndrome coronavirus (MERS-CoV) Common to SARS Severe acute respiratory syndrome 100 deaths in the Middle East from 2012 to 2014

Emerging Infectious Diseases Avian influenza A (H5N1) Influenza A virus Primarily in waterfowl and poultry Sustained human-to-human transmission has not yet occurred

Figure 13.3b Morphology of an enveloped helical virus. Spikes

Emerging Infectious Diseases Methicillin-resistant Staphylococcus aureus (MRSA) 1950s: Penicillin resistance developed 1980s: Methicillin resistance 1990s: MRSA resistance to vancomycin reported VISA: vancomycin-intermediate S. aureus VRSA: vancomycin-resistant S. aureus

Emerging Infectious Diseases West Nile encephalitis (WNE) 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 48 states Transmitted between birds and to horses and humans by mosquitoes

Diseases in Focus 22.2 (1 of 3)

Emerging Infectious Diseases Bovine spongiform encephalopathy Caused by a prion An infectious protein that also causes Creutzfeldt-Jakob disease (CJD) New variant of CJD in humans is related to cattle that have been given feed made from prion-infected sheep

Figure 22.18b Spongiform encephalopathies. Holes

Emerging Infectious Diseases E. coli O157:H7 Toxin-producing strain of E. coli First seen in 1982; causes bloody diarrhea Leading cause of diarrhea worldwide

Figure 25. 11 Pedestal formation by Enterohemorrhagic E Figure 25.11 Pedestal formation by Enterohemorrhagic E. coli (EHEC) O157:H7.

Emerging Infectious Diseases Ebola hemorrhagic fever (EHF) Ebola virus Causes fever, hemorrhaging, and blood clotting Transmitted via contact with infected blood or body fluids First identified near Ebola River, Congo 2014 outbreak in Guinea; hundreds killed

Figure 23.21 Ebola hemorrhagic virus.

Emerging Infectious Diseases Cryptosporidiosis Cryptosporidium protozoa First reported in 1976 Causes 30% of diarrheal illness in developing countries In the United States, transmitted via water

Figure 25.17 Cryptosporidiosis. Intestinal mucosa Oocyst

Emerging Infectious Diseases AIDS (acquired immunodeficiency syndrome) Caused by human immunodeficiency virus (HIV) First identified in 1981 Sexually transmitted infection affecting males and females Worldwide epidemic infecting 35 million people; 6000 new infections every day HIV/AIDS in the United States: 26% are female, and 49% are African American

Check Your Understanding Differentiate normal microbiota and infectious disease. 1-16 Why are biofilms important? 1-17 What factors contribute to the emergence of an infectious disease? 1-18