FA 2024 Chapter 1 Microbial World (PDF)

Microbiology: An Introduction Fourteenth Edition Chapter 1 The Microbial World and You Normal Intestinal...

Microbiology: An Introduction Fourteenth Edition Chapter 1 The Microbial World and You Normal Intestinal Bacteria Copyright © 2024 Pearson Education, Inc. All Rights Reserved Microbes in Our Lives Microorganisms are organisms that are too small to be seen with the unaided eye There are 5 main types of Microbes: 1.Bacteria 2. Fungi 3. Protozoa 4. microscopic Algae 5. Viruses and prions Copyright © 2024 Pearson Education, Inc. All Rights Reserved  Roles of Microbes A few are pathogenic (disease- producing) Some cause food spoilage Decompose organic waste Incorporate nitrogen gas in air into organic compounds Generate oxygen by photosynthesis Produce chemical products such as ethanol, acetone, and vitamins Produce fermented foods such as vinegar, cheese, yogurt, alcoholic beverages, and bread Produce products used in manufacturing (e.g., cellulose) and disease treatment (e.g., insulin) Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Microbiome An adult human is composed of 30 trillion body cells – Harbors another 40 trillion bacterial cells The microbiome (microbiota) is a group of microbes that live stably on/in the human body – Help to maintain good health – Can prevent growth of pathogenic microbes – May help train the immune system to discriminate threats Copyright © 2024 Pearson Education, Inc. All Rights Reserved Copyright © 2024 Pearson Education, Inc. All Rights Reserved  The Microbiome Normal microbiota: the collection of acquired microorganisms on or in a healthy human being – Begin to be acquired before birth – May colonize the body indefinitely – May colonize the body fleetingly (making them transient microbiota) Colonization can only occur at body sites that provide nutrients and the right environment for the microbes to flourish Copyright © 2024 Pearson Education, Inc. All Rights Reserved  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 Escherichia coli – Honors the discoverer, Theodor Escherich – Describes the bacterium’s habitat —the large intestine, or colon Staphylococcus aureus – Describes the clustered (staphylo-) spherical (coccus) cells – Describes the gold-colored (aureus) colonies Copyright © 2024 Pearson Education, Inc. All Rights Reserved Binomial Nomenclature Scientific names – Are italicized or underlined. – The genus is capitalized; the specific epithet (species name) is lowercase – Are “Latinized” and used worldwide – May be descriptive or honor a scientist. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Bacteria Prokaryotes – “Prenucleus” Single-celled (unicellular) Peptidoglycan cell walls Divide via binary fission Derive nutrition from organic or inorganic chemicals or photosynthesis May “swim” by using moving appendages called flagella Copyright © 2024 Pearson Education, Inc. All Rights Reserved Archaea Are prokaryotes Lack peptidoglycan cell walls – May lack cell wall entirely Often live in extreme environments Include: – Methanogens – Extreme halophiles – Extreme thermophiles Not known to cause disease in humans Copyright © 2024 Pearson Education, Inc. All Rights Reserved Fungi Eukaryotes – Distinct nucleus consisting of the cell’s genetic material (DNA) surrounded by a nuclear membrane 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 Copyright © 2024 Pearson Education, Inc. All Rights Reserved 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) – Some are photosynthetic Reproduce sexually or asexually Copyright © 2024 Pearson Education, Inc. All Rights Reserved Algae Eukaryotes Cellulose cell walls Found in freshwater, saltwater, and soil Use photosynthesis for energy – Produce oxygen and carbohydrates Sexual and asexual reproduction possible Copyright © 2024 Pearson Education, Inc. All Rights Reserved 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 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Multicellular Animal Parasites: Helminths Eukaryotes Multicellular animals Not strictly microorganisms Parasitic flatworms and roundworms are called helminths Some microscopic stages in their life cycles Which groups of microbes are prokaryotes? Which are eukaryotes? Copyright © 2024 Pearson Education, Inc. All Rights Reserved Classification of Microorganisms Developed by Carl Woese in 1978 Three domains based on cellular organization – Bacteria – Archaea – Eukarya ▪ Protists ▪ Fungi ▪ Plants ▪ Animals Copyright © 2024 Pearson Education, Inc. All Rights Reserved A Brief History of Microbiology 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 and documented with detailed drawings from 1673 to 1723 by Anton van Leeuwenhoek – “Animalcules” (bacteria, protozoa) viewed through magnifying lenses Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Debate over Spontaneous Generation Two opposing hypotheses regarding the origin of organisms: 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 Copyright © 2024 Pearson Education, Inc. All Rights Reserved  The Debate over Spontaneous Generation 1668: Francesco Redi filled jars with decaying meat Conditions Results Jars covered with fine net No maggots Opened jars Maggots appeared Sealed jars No maggots Where did the maggots come from? What was the purpose of the sealed jars? Copyright © 2024 Pearson Education, Inc. All Rights Reserved Spontaneous generation or biogenesis? The Debate over Spontaneous Generation 1745: John Needham put boiled nutrient broth into covered flasks 1765: Lazzaro Spallanzani boiled nutrient solutions in sealed flasks Conditions Results Nutrient broth heated, then placed in Microbial growth covered (not sealed) flask Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Theory of Biogenesis 1858: Rudolf Virchow stated that living cells arise from preexisting cells 1861: Louis Pasteur demonstrated that microorganisms are present in the air Conditions Results Nutrient broth placed in flask, heated, Microbial growth Not sealed Nutrient broth placed in flask, heated, No microbial growth then immediately sealed Spontaneous generation or biogenesis? Copyright © 2024 Pearson Education, Inc. All Rights Reserved Disproving Spontaneous Generation Microorganisms originate in air or fluids, not mystical forces For Long description, see slide 109: Appendix 8 Copyright © 2024 Pearson Education, Inc. All Rights Reserved The First Golden Age of Microbiology (1 of 3) 1857–1914 Discoveries and developments included the following: – relationship between microbes and disease – role of immunity in preventing disease – studies of the chemical activities of microorganism – improved microscopy – methods to culture (grow) microorganisms – first vaccines – aseptic techniques – first use of chemotherapeutic drugs Copyright © 2024 Pearson Education, Inc. All Rights Reserved Milestones in the First Golden Age of Microbiology For Long description, see slide 116: Appendix 15 (1 of 2) Copyright © 2024 Pearson Education, Inc. All Rights Reserved The First Golden Age of Microbiology Pasteurization 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 Copyright © 2024 Pearson Education, Inc. All Rights Reserved The First Golden Age of Microbiology (1857–1914) 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) Copyright © 2024 Pearson Education, Inc. All Rights Reserved  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. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Germ theory of disease: Koch’s postulates (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. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Vaccination 1796: Edward Jenner inoculated a person with cowpox virus, who was then immune to smallpox Vaccination is derived from the Latin word vacca, meaning cow The protection is called immunity Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Second Golden Age of Microbiology: Birth of Modern Chemotherapy Focus on treating diseases caused by microbes 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 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Birth of Modern chemotherapy: “Magic Bullet” The first synthetic drug: Paul Ehrlich speculated about a “magic bullet” that could destroy a pathogen without harming the host 1910: Ehrlich developed a synthetic arsenic-based drug, Salvarsan, to treat syphilis 1930s: Sulfonamides were synthesized A Fortunate Accident-Antibiotic: 1928: Alexander Fleming discovered the first antibiotic (by accident) Fleming observed that Penicillium fungus made an antibiotic, penicillin, that killed S. aureus Copyright © 2024 Pearson Education, Inc. All Rights Reserved Problems with Antimicrobial Chemicals Overuse can lead to resistance. Vancomycin resistant Staphylococcus aureus Some drugs can be toxic to humans – Especially true of many antiviral drugs Research used to overcome these problems has ushered in a Third Golden Age of Microbiology from the late 1980s to the present Copyright © 2024 Pearson Education, Inc. All Rights Reserved Bacteriology, Mycology, and Parasitology Bacteriology is the study of Parasitology bacteria Mycology is the study of fungi Parasitology is the study of protozoa and parasitic worms Immunology is the study of immunity – Vaccines and interferons Rebecca Lancefield are used to prevent and treat viral diseases A major advance in immunology occurred in 1933 when Rebecca Lancefield classified streptococci based on their cell wall components Copyright © 2024 Pearson Education, Inc. All Rights Reserved Virology Virology is the study of viruses Dmitri Iwanowski in 1892 and Wendell Stanley in 1935 discovered the cause of mosaic disease of tobacco to be a virus Electron microscopes have made it possible to study the structure of viruses in detail Copyright © 2024 Pearson Education, Inc. All Rights Reserved Molecular Genetics Microbial genetics: the study of how microbes inherit traits Molecular biology: the study of how genetic information is carried in molecules of D N A Oswald Avery, Colin MacLeod, and Maclyn McCarty showed that DNA is the hereditary material James Watson and Francis Crick proposed a model of DNA structure Copyright © 2024 Pearson Education, Inc. All Rights Reserved  The Third Golden Age of Microbiology Genomics: the study of an organism’s genes – Has provided new tools for discovering, detecting, and classifying microorganisms – Has enabled study of microbiomes in diverse ecological niches as well as their role in disease 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 – Enables manufacture of large amounts of human hormones and other proteins within bacteria or other microbes Copyright © 2024 Pearson Education, Inc. All Rights Reserved 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 Sewage treatment: Using microbes to recycle water. Sewage is 99.9% water, with a few hundredths of 1% suspended solids Treatment of sewage removes undesirable components so water can be released or reused – Large solids are removed physically – Microbes are used to convert left over liquid and organic materials into by-products such as carbon dioxide, nitrates, phosphates, sulfates, ammonia, hydrogen sulfide, and methaneCopyright © 2024 Pearson Education, Inc. All Rights Reserved 3. Bioremediation: Using microbes to clean up pollutants Bacteria degrade organic matter in sewage Bacteria degrade or detoxify pollutants such as oil and mercury 4. 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 The bacteria produce protein crystals toxic to insects The toxin gene has been inserted into some plants to confer insect resistance. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Biotechnology and Recombinant DNA Technology Biotechnology is the use of microbes for practical applications, such as producing foods and chemicals Recombinant D N A 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 – Agricultural applications: Genetically modified bacteria are used to protect crops from insects and from freezing Copyright © 2024 Pearson Education, Inc. All Rights Reserved  Normal Microbiota Microbes normally present in and on the human body are called 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 of our immune system Copyright © 2024 Pearson Education, Inc. All Rights Reserved Biofilms Microbes attach to solid surfaces and grow into complex masses They will grow on rocks, pipes, teeth, and medical implants Some biofilms are beneficial – Protect mucous membranes from harmful organisms – Provide food in aquatic ecosystems Some biofilms are harmful – Clog water pipes – Cause infections on medical implants – Often bacteria in biofilms are resistant to antibiotics Copyright © 2024 Pearson Education, Inc. All Rights Reserved  Emerging Infectious Diseases Infectious disease: disease that results when a pathogen invades a host and overcomes the host's resistance. Emerging infectious diseases (EID s): new diseases and diseases increasing in incidence Factors contributing to emergence of diseases include: – Evolutionary changes such as antibiotic resistance – Modern transportation enabling rapid dispersal of diseases – Increased human exposure to infectious agents due to deforestation and construction Copyright © 2024 Pearson Education, Inc. All Rights Reserved  Emerging Infectious Diseases Coronavirus Disease—2019 (COVID- 19) – First recognized in China in December 2019 – Severe acute respiratory coronavirus- 2 (SAR S-CoV-2) – March 2020: COVID-19 was declared a pandemic by the World Health Organization (W H O) Two prior emergences of zoonotic coronaviruses that cause severe respiratory disease: ▪ 2002: Severe acute respiratory syndrome (SAR S) – SAR S-Coronavirus ▪ 2012: Middle East respiratory syndrome (M E R S) – MERS-Coronavirus Copyright © 2024 Pearson Education, Inc. All Rights Reserved  Emerging Infectious Zika virus disease – Spread by bite of an infected Aedes mosquito; also transmitted by sexual contact – Disease is typically mild, with fever, rash, and joint pain – Infection during pregnancy can result in severe birth defects Antibiotic-Resistant Infections – Methicillin-resistant Staphylococcus aureus (MRSA) ▪ 1950s: Penicillin resistance developed ▪ 1980s: Methicillin resistance ▪ 1990s: MRSA resistance to vancomycin reported – VRSA: vancomycin-resistant S. aureu Ebola virus disease – Virus: Ebolavirus – Causes fever, hemorrhaging, and intravascular blood clotting – Transmitted via contact withCopyright © 2024 Pearson Education, Inc. All Rights Reserved infected blood or body fluids