Why Study Microbiology? Infectious and parasitic diseases cause more than 25% of annual deaths worldwide (second leading cause of death). - Lower respiratory infections - HIV-AIDS - Diarrheal diseases - Malaria - TB - Measles - Whooping cough

Why Study Microbiology? Many diseases – some we thought were under control – are re-emerging. - Travel - Global food market - Anti-vaccine movement - Homeless; crowding - Multi-drug resistance - Global climate change - Inadequate health resources

Why Study Microbiology? Microorganisms being linked to diseases that were once not recognized as infectious diseases.  Example: Peptic Ulcers  As late as the 1980’s, experts believed peptic ulcers were a result of lifestyle, “smoking, drinking alcohol, stress, and genetic predisposition.”  Causative agent: Helicobacter pylori

Microorganisms Beneficial  Used in food production  Source of antibiotics  Normal flora  Algae responsible for 80% of earth’s photosynthesis

Microorganisms Beneficial  Break down organic matter  Help plants grow – nitrogen cycle  Genetic engineering hosts

What Will We Study? Bacteria Yeasts Molds Control of organisms Immune response Epidemiology Viruses Protozoans and Helminths

Copyright © 2011 Pearson Education Inc. The Fields of Microbiology Table 1.3

Copyright © 2011 Pearson Education Inc. MICROBIOLOGY Figure 1.18 The study of organisms that are too small to be seen with the unaided eye known as microorganisms or microbes.

Figure 1.7: Streptococcus within a human cheek cell 10  m LM Prokaryotic bacterial cells Eukaryotic cheek cell

Copyright © 2011 Pearson Education Inc. FIRST OBSERVATIONS Figure , Antoni van Leeuwenhoek -Began making and using simple microscopes -Examined water and visualized tiny animals, fungi, algae, and single-celled protozoa; “animalcules” – -Now called microorganisms

Copyright © 2011 Pearson Education Inc. The Theory of Spontaneous Generation Some philosophers and scientists of the past thought living things arose from three processes: asexual reproduction, sexual reproduction, or from nonliving matter Aristotle proposed spontaneous generation – “Living things can arise from nonliving matter.” According to spontaneous generation, a “vital force” forms life.

Copyright © 2011 Pearson Education Inc. The Golden Age of Microbiology Many scientists began doubting Aristotle’s theory and performed experiments to disprove the theory of spontaneous generation – Redi – – decaying meat isolated from flies never developed maggots – Needham- – Believed animals could not reproduce spontaneously, but microbes could – Spallanzani- – Proved microbes exist in air and can contaminate experiments

Copyright © 2011 Pearson Education Inc. The Golden Age of Microbiology Louis Pasteur’s “Swan neck Flask” Experiment – disproved Spontaneous Generation theory

Copyright © 2011 Pearson Education Inc. The Golden Age of Microbiology Debate over spontaneous generation was linked to the question: What Causes Fermentation? – Spoiled wine threatened livelihood of vintners – Some believed air caused fermentation; others insisted living organisms caused fermentation

Copyright © 2011 Pearson Education Inc. The Golden Age of Microbiology Pasteur showed that microbes are responsible for fermentation. – Fermentation is the conversion of sugar – to alcohol (to make beer and wine) – or to acids (ie.lactic acid, acetic acid)

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings  Bacteria ferment sugar and produce acetic acid, thus spoiling wine by turning it to vinegar (acetic acid).  Pasteur demonstrated these spoilage bacteria could be killed by heat that was not hot enough to evaporate the alcohol in wine.  This is called pasteurization. Pasteurization Figure 1.4

Copyright © 2011 Pearson Education Inc. The Golden Age of Microbiology What Causes Disease? – Pasteur developed the germ theory of disease – Microbes cause disease, not “evil spirits” “bad air” or “punishments from the gods” – Pathogen – specific germ that causes disease (infectious agent)

Copyright © 2011 Pearson Education Inc. The Golden Age of Microbiology (Continued) Robert Koch ( ) Theorized that a “specific microbe causes a specific disease” Developed experimental steps to prove that Bacillus anthracis causes anthrax

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Koch’s Postulates 1.The causative agent must be seen in case of every disease. 2.The causative agent must be isolated in pure culture. 3.Inoculating the pure culture into healthy, susceptible animal must produce the same disease. 4.The causative agent must be recovered from the inoculated animal.

Copyright © 2011 Pearson Education Inc. The Golden Age of Microbiology Koch’s Other Contributions – Simple staining techniques – First photomicrograph of bacteria – First photomicrograph of bacteria in diseased tissue – Techniques for estimating CFU/ml – Use of steam to sterilize media – Use of Petri dishes – Techniques to transfer bacteria – Bacteria as distinct species

Copyright © 2011 Pearson Education Inc. Bacterial colonies on agar Figure 1.16

Copyright © 2011 Pearson Education Inc. The Golden Age of Microbiology How Can We Prevent Infection and Disease? – Semmelweis and handwashing – Lister’s antiseptic technique – Nightingale and nursing – Snow – infection control and epidemiology – Jenner’s vaccine – field of immunology

Copyright © 2011 Pearson Education Inc. The Golden Age of Microbiology (Continued) How can we prevent infection and disease?  Ignaz Semmelweis advocated handwashing to prevent transmission of puerperal fever (childbed fever) in OB patients  and-saved-women-s-lives and-saved-women-s-lives  Joseph Lister used a chemical disinfectant and aseptic technique to prevent surgical wound infections after seeing Pasteur’s work showing microbes are in the air

Copyright © 2011 Pearson Education Inc. The Golden Age of Microbiology (Continued)  Florence Nightingale introduced antisepsis and aseptic technique into nursing practices  John Snow– was a pioneer in public hygiene, infection control and epidemiology during a cholera outbreak  Edward Jenner developed vaccinations by inoculating a person with cowpox virus in hopes it would then protect him from smallpox. The protection is called immunity

Copyright © 2011 Pearson Education Inc. The Golden Age of Microbiology (Continued) How do we treat infectious diseases?  Paul Ehrlich’s “magic bullets” – field of chemotherapy  Alexander Fleming discovered the first antibiotic from observing the mold Penicillium killed Staphylococcus.

Copyright © 2011 Pearson Education Inc. The Golden Age of Microbiology Discovery of viruses  Dmitri Ivanovsky, Russian botanist (1892) – suggested a plant infection might be caused by a filterable toxin produced by bacteria  Martinus Beijerinck, Dutch microbiologist (1898) – convinced that the filtered solution contained a new form of infectious agent, which he named virus meaning poison By the end of the 19th century, viruses were defined in terms of their infectivity, their ability to be filtered, and their requirement for living hosts. The first images of viruses were obtained upon the invention of electron microscopy in 1931

Copyright © 2011 Pearson Education Inc. The Modern Age of Microbiology Microbial Genetics Genomics- the study of an organism’s genes Eduard Buchner (1897) – Discovered enzymes catalyzed fermentation Beadle and Tatum (1942) - Enzymes (proteins) are encoded in genes Avery, MacLeod, and McCarty (1944) - DNA is the hereditary material -not protein Jacob and Monod (1961) - Discovered the role of mRNA in protein synthesis

Copyright © 2011 Pearson Education Inc. The Modern Age of Microbiology Genome Sequencing- the study of the order of genes in a genome  Pauling (1965)  Provided understanding of evolutionary relationships and processes  Carl Woese (1970’s)  Discovered three cell groups (instead of two)  bacteria, archaea, eukaryotes

Copyright © 2011 Pearson Education Inc. The Modern Age of Microbiology  Genetic engineering – Manipulate genes in microbes, plants, and animals for practical applications – Paul Berg (1960s) – Studied recombinant DNA technology DNA from two or more sources is incorporated into a single recombinant molecule – Gene therapy – Inserting a missing gene or repairing a defective one in humans by inserting desired gene into host cells

Copyright © 2011 Pearson Education Inc. The Modern Age of Microbiology What Role Do Microbes Play in the Environment? – Microbial Ecology- the study of interrelationships between organisms and their environment – Bioremediation uses living bacteria, fungi, and algae to detoxify polluted environments

Copyright © 2011 Pearson Education Inc. Bioremediation Oil spill Spraying bacteria or fertilizer on spill Clean rocks

Copyright © 2011 Pearson Education Inc. Scientific disciplines and applications Figure 1.19

Copyright © 2011 Pearson Education Inc. The Future of Microbiology The more questions we answer, the more questions we have” Why can’t we grow some microbes in the lab? What can we learn from microbial communities What microbial genes cause pathogenicity How do we defend against microbes at the genetic level How do we reduce threat of new and re-emerging infectious diseases?