Chapter 1 a Brief History of Microbiology

Chapter 1 A Brief History of Microbiology

I. Microbiology Introduction A. General information 1. 1/3 of world’s population live on less than $1.00/day, are malnourished, and not immunized 2. approximately 12 million people worldwide die each yr. from infections 3. bacteria evolved over 3.5 billion yrs. ago 4. microbes make up by weight 2/3’s of Earth’s living material

5. through photosynthesis microbes produce about 50% of the O2 we use 6. normal flora – microorganisms that begin to colonize body at birth – live in/on body – healthy state 7. opportunistic pathogens – organism doesn’t usually cause disease; due to circumstances disease can occur – yeast infections, thrush, staph B. Study of microorganisms 1. mycology (study of fungi) 2. Parasitology (study of parasites) 3. virology (study of viruses – over 3600 known viruses) 4. bacteriology (study of bacteria – over 10 million known species) 5. protozoology (study of protozoa – like the amoeba) 6. phycology (study of algae) 7. helminthes (parasitic worms) II. The Early Years of Microbiology A. What does life really look like: 1. Antoni van Leeuwenhoek (Dutch) 1632-1723 a. lens grinder and tailor b. made/used simple microscopes c. looked at water and saw tiny animals, fungi, algae, and protozoa: animalcules 2. all are now called microbes/microorganisms B. How can microbes be classified 1. Carolus Linnaeus – 1707-1778 a. taxonomic system b. groups similar organisms together and gives them names c. still used today 2. Leeuwenhoek’s microorganisms grouped into 6 categories a. bacteria b. archaea c. fungi d. protozoa e. algae f. small multicellular animals C. Bacteria and archaea 1. prokaryote 2. unicellular 3. much smaller than eukaryotes 4. found where sufficient moisture is found 5. reproduce asexually 6. 2 kinds a. bacteria -cell walls composed of peptidoglycan -detritivores -can cause disease -most are beneficial b. archaea -cell walls composed of polymers other than peptidoglycan -found in extreme environments -do not cause disease D. Fungi 1. eukaryotic 2. consumer 3. have cell walls 4. includes: a. molds -multicellular -grow as long filaments -reproduce sexually and asexually by spores b. yeast -unicellular -reproduce asexually by budding or sexually by spores E. Protozoa 1. eukaryotic 2. unicellular 3. found in water, animals 4. asexual and sexual reproduction 5. most are capable of locomotion a. pseudopodia b. cilia c. flagella F. Algae 1. unicellular or multicellular 2. photosynthetic 3. simple reproductive structures 4. grouped based on color, storage products, and composition of cell wall G. parasitic worms (helminthes) 1. immature stage microscopic 2. adult stage often visible with naked eye H. viruses 1. only seen with electron microscope (1932) 2. acellular obligate parasites III. The Golden Age of Microbiology (late 1800’s-early 1900’s) A. Scientists searched for answers to 4 questions 1. Is spontaneous generation of microbial life possible? 2. What causes fermentation? 3. What causes disease? 4. How can we prevent infection and disease? 5. Discoveries led to: a. scientific method b. industrial microbiology (biotechnology) c. biochemistry d. etiology (cause of disease) e. infection control f. epidemiology (study of occurrence, distribution, and spread of human disease) g. immunology B. Some thought living things arose from 3 processes 1. asexual reproduction 2. sexual reproduction 3. nonliving matter – spontaneous generation or abiogenesis C. Aristotle – 384-322 B.C. 1. proposed spontaneous generation 2. lasted 2,000 years 3. not challenged until 17th century D. Redi’s experiments 1. involved jars of raw meat covered and uncovered 2. uncovered meat had flies and then maggots; covered meat did not 3. result – doubting of Aristotle’s theory E. Needham’s experiments 1. boiled beef gravy and infusions of plant material 2. broth placed in flask sealed with cork 3. broth turned cloudy with microbes in a few days 4. reinforced Atistotle’s theory F. Spallanzani’s experiments 1. repeated Needham’s experiments but melted neck of flask 2. broth remained microbe free 3. conclusion: a. Needham failed to heat vials enough to kill microbes and/or had not sealed flasks properly\ b. microorganisms exist in air and can contaminate experiments c. Spontaneous generation does not occur 4. critics: a. sealed flasks didn’t allow enough air for organisms to survive b. overheated and killed everything G. Pasteur’s experiments – finally proved biogenesis - 1859 1. repeated Spallanzani’s experiment but bent neck of flask 2. when “swan-necked” flasks remained upright (18 mos.) no microbial growth 3. when flask tilted, dust from bend in neck seeped back into flask and made infusion cloudy with microbes within a day H. Scientific Method 1. debate led in part to scientific method: a. observation leads to questions b. question generates hypothesis c. hypothesis tested through carefully controlled experiment d. results prove or disprove hypothesis -accepted hypothesis leads to theory/law -reject or modify hypothesis I. What causes fermentation? 1. spoiled win threatened livelihood of 19th century French vintners 2. some believed air caused fermentation 3. others said living organisms caused it 4. this debate also linked to debate about spontaneous generation 4. vintners funded research to prevent spoilage during fermentation a. reached out to Pasteur b. due to Pasteur’s research for vintners, he developed germ theory of fermentation - yeast ferment grape juice into alcohol -bacteria ferment grape juice into acids c. heat wine – Pasteurization – kills bacteria and reduces their # 5. Buchner’s experiment a. fermentation does not require living cells b. enzymes promote chemical reaction J. What causes disease? 1. Pasteur a. germ theory of disease - 1857 -microorganisms cause disease -linked to discovery that bacteria spoiled wine b. led to etiology – study of cause of disease c. known as Father of Microbiology 2. Robert Koch studied causative agents of disease – 1843-1910 a. studied anthrax b. examined colonies of microorganisms c. proved bacteria caused anthrax K. Koch’s contributions 1. simple staining techniques 2. 1st photomicrograph of bacteria 3. 1st photomicrograph of bacteria in diseased tissue 4. techniques of estimating CFU/mL (colony forming units per milliliter) 5. use of steam to sterilize media 6. use of petri dishes 7. developed solid culture surface (agar) 8. techniques to transfer bacteria 9. bacteria as distinct species L. Koch’s postulates – series of steps one must take to prove cause of any infectious disease 1. suspected causative agent must be found in every case of the disease and be absent from healthy host 2. agent must be isolated and grown outside host 3. when agent is introduced into a healthy, susceptible host, host must get disease 4. same agent must be found in diseased experimental host M. Gram’s Stain – 1844 1. Danish scientist Hans Christian Gram developed more important staining technique than Koch’s 2. involves applications of series of dyes 3. some microbes turn purple – Gram positive 4. some microbes turn pink – Gram negative 5. gram procedure used to separate organisms into 2 groups 6. most widely used staining technique N. How can we prevent infection and disease? 1. Semmelweis and handwashing – 1818-1865 a. ob dr. b. wash hands with chlorinated lime water c. mortality rate dropped from 18.3% to 1.3% 2. Joseph Lister’s antiseptic technique - 1827-1912 a. sprayed wounds/surgical incisions/dressings with carbolic acid b. death rate dropped by 2/3’s 3. Florence Nightingale and nursing a. set standards of hygiene b. opened 1st nursing school 4. John Snow - 1854 a. during cholera epidemic in London discovered it spread by contaminated water b. laid groundwork for our public health systems and water treatment c. led to infection and epidemiology 5. Edward Jenner’s smallpox vaccine -1796 a. cowpox material from milkmaid scratched into skin of James Phipps and his son b. neither got smallpox c. led to field of immunology 6. Paul Ehrlich’s magic bullets – 1854-1915 a. salvarsan – cpd. of arsenic to cure syphilis and sleeping sicknesses b. led to field of chemotherapy 7. Pasteur - vaccines for anthrax, fowl cholera, rabies, and chicken pox III. The Modern Age of Microbiology A. Beijerinck – 1932 – discovered viruses B. Polio vaccine 1. Jonas Salk – 1955 – injection 2. Albert Sabin – 1961 – oral polio vaccine C. What are the basic chemical reactions of life? 1. biochemistry – study of metabolism a. began with Pasteur’s and Buchner’s works b. microbes used as model systems for biochemical reactions c. practical applications -design of herbicides and pesticides -diagnosis of illness and monitoring responses to treatment -treatment of metabolic diseases -drug design D. How do genes work? 1. microbial genetics 2. molecular biology 3. recombinant DNA technology 4. gene therapy E. Microbial genetics 1. Avery, MacLeod, and McCarty: genes are contained in molecules of DNA 2. Beadle and Tatum: a gene’s activity is related to function of the specific protein coded for by that gene 3. Translation of genetic information into protein explained 4. rates and mechanisms of genetic mutation investigated 5. control of genetic expression by cells described F. molecular biology 1. explanation of cell function at molecular level – genome sequencing 2. Linus Pauling proposed gene sequences could: a. provide understanding of evolutionary relationships/processes b. establish taxonomic categories c. identify microbes that have never been cultured (some can’t be cultured in lab setting such as bacteria that causes Cat Scratch Disease) 3. Woese determined cells belong to bacteria, archaea, or eukaryotes G. Recombinant DNA technology – genetic engineering 1. genes in microbes, plants, and animals manipulated for practical applications 2. production of human blood-clotting factor by E.coli to aid hemophiliacs H. gene therapy 1. inserting a missing gene 2. repairing a defective one by inserting desired gene into host cells I. What roles do microorganisms play in the environment? 1. bioremediation uses living bacteria, fungi, and algae to detoxify polluted environments 2. recycling of chemicals such as carbon, nitrogen, and sulfur J. How do we defend against disease? 1. serology a. study of blood serum -clear, yellowish, fluid part of blood. Does not contain cells or clotting factor. Does include some proteins, electrolytes, antibodies, antigens, hormones, and any extra substances such as drugs and microorganisms b. blood has chemicals and cells that fight infection 2. immunology -the study of body’s defense against specific pathogens 3. chemotherapy a. Sir Alexander Fleming – 1881-1955 - accidentally discovered penicillin - 1928 - comes from green mold Penicillium notatum b. Domagk – discovered sulfa drugs K. Future of Microbiology 1. New concerns in microbiology a. emerging infectious diseases (diseases recently surfaced in populations): SARS, Ebola, West Nile virus, Hepatitis C b. re-emerging infectious diseases (diseases that have existed in past but are now showing a resurgence in incidence or a spread in geographic range): Group A Strep, mumps, Staphylococcus aureus, rabies, malaria, TB, cholera, salmonella, Pertussis (whooping cough), Pneumococcus, E. coli, giardiasis c. super microbes – drug resistant d. polymicrobial diseases – 1 disease caused by more than 1 infectious agent: acute necrotizing ulcerative gingivitis, some respiratory diseases, some middle ear infections, Multiple Sclerosis, Pertussis, Hepatitis, gastroenteritis, genital infections e. bioterrorism 2. What prevents certain life forms from being grown in labs? 3. Can microorganisms be used in ultraminiature technologies such as computer circuit boards? 4. How can understanding of microbial communities help us understand communities of larger? organisms?