A Brief History of Microbiology

Transcription

1 PowerPoint Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University C H A P T E R 1 A Brief History of Microbiology

2 Main chapter concepts Microbes are important! Very few actually cause disease How microbes are defined Living things that are found in all 3 domains and their characteristics Important players in early microbiological studies van Leeuwenhoek, Pasteur, Spallanzani, Needham, Koch, Gram, Nightingale, Lister, Jenner How Pasteur s work lead to scientific method Koch s postulates

3 What do you think of when you hear the word microorganism? Disease Food? Environment?

4 Microbes are a huge part of our lives!! Produce industrial chemicals such as ethanol and acetone Produce fermented foods such as vinegar, cheese, and bread Produce medical products such as insulin Produce our blue jeans (stone washing, dyes)

5 Only a FEW microorganisms are PATHOGENIC Cutaneous anthrax Strep throat Tetanus

6 Microbes are a huge part of our lives!! Important in nutrient cycling in the environment Decomposers and producers Microbes even aid in animal digestion!!

7 PLUS: Your body is an ecosystem of microbes!! You have 10X more bacterial cells in your body than your own cells! You carry at ~3lbs of bacteria

8 The human microbiome is currently a huge area of study Scientists are finding links to people s microbes to diseases such as diabetes, depression, gluten intolerance, and IBS Can we treat diseases by altering the microbes in people s bodies??? news.harvard.edu

9 So what exactly is a microorganism? Microorganisms = any living thing that is too small to be seen with the unaided eye fungus protist bacteria virus Parasitic worm

10 Microorganisms are living things that are too small to see with the unaided eye (and there are LOTS of them!!) More than a million bacteria can fit into the eye of a needle Microbial biomass is 10,000X greater than all human biomass! And we have cultured less than 1%

11 Biology rewind: What is life? All living things exhibit the following processes: Growth Reproduction Responsiveness Metabolism Evolve The basic unit of life is the cell

12 Biology rewind: All life is made of cells Anything considered alive must have at least one cell!! There are TWO types of cells: Bacteria, Archaeans Everything else No nucleus Has nucleus

13 Figure 1.4 Cells of the bacterium Streptococcus (dark blue) and two human cheek cells. Prokaryotic bacterial cells Nucleus of eukaryotic cheek cell Bacteria = 1-10μm Eukaryotic cell = 10μm 100μm

14 All living things fit into three categories called domains (Microbes can be found in all three) Prokaryotes Eukaryotes Image from:

15 Most of the microbes we will discuss in class and lab are found in these two domains Domain Bacteria Domain Archaea All species in these two domains are single-celled and prokaryotic

16 The prokaryotes: Bacteria and Archaea General characteristics Unicellular Lack nuclei (prokaryotic) Much smaller than cells with a nucleus (nucleus = eukaryotic) Found virtually everywhere; some even in extreme environments Reproduce asexually

17 Microorganisms are also found in the Domain Eukarya, which have a nucleus Protists Plants Animals Fungi Fungi Protozoans Algae

18 Domain Eukarya: Fungi General characteristics Eukaryotic (have a nucleus) Obtain food from other organisms Possess cell walls Single cellular and multicellular Sexual and asexual reproduction

19 Figure 1.5 Fungi. Hyphae Spores Budding cells Multicellular = many cells Unicellular = single celled

20 Domain Eukarya: The protozoans General characteristics Single-celled eukaryotes Similar to animals in nutritional needs and cellular structure Live freely in water; some live in animal hosts Asexual and sexual reproduction Most are capable of locomotion by psedudopods, cilia, and flagella

21 Figure 1.6 Locomotive structures of protozoa. Nucleus Pseudopods Cilia Amoeba sp. Flagellum Euplotes sp. Peranema sp.

22 Domain Eukarya: Algae (plant-like protists) General characteristics Eukaryotic Unicellular or multicellular Have a cell wall Photosynthetic Categorized on the basis of pigmentation and composition of cell wall (not all are considered plants!)

23 Figure 1.7 Algae Spirogyra sp. Diatoms

24 Other things of interest to microbiologists parasites viruses Eggs and larval stages very small, must be studied with microscope Were too small to be seen by early microbiologists Acellular, only made of nucleic acid and protein Not considered living!

25 Let s talk a little about the history of the field of microbiology Ugh!! History... Why do we have to talk about boring history?? The history of microbiology is the history of the field of science! Studying microbes gave us the scientific method Many of the same principles started in the past are still used today!

26 The existence of microbes was unknown until the late 1600 s Illustration by artist Robert Seymour of the concept of miasma during a Cholera outbreak

27 Antoni van Leeuwenhoek is credited with discovering the first microbes His findings started the Early Years of microbiology Scientists principally focused on identifying and classifying microbes

28 The discovery and identification of microbes led to the Golden Age of Microbiology ( ) Scientists searched for answers to four questions Is spontaneous generation of microbial life possible? What causes fermentation? What causes disease? How can we prevent infection and disease?

29 Spontaneous generation: Life comes from nonlife Aristotle perpetuated idea of abiogenesis, that life can come from nonlife, which was accepted for over 2000 years

30 Francesco Redi proposed the first experiments to suggest that the spontaneous generation of large organisms is not true (late1600s) Meat exposed to flies = maggots Meat not exposed = no maggots Meat covered with gauze = maggots on gauze

31 Well, maybe microbes can still spontaneously generate? Needham vs. Spallanzani Needham boiled beef infusions then sealed with cork = days later, microbes Spanllazani boiled beef infusions then sealed the glass containers = no microbes Detractors of Spanllazani said there is a life force in the air

32 So is spontaneous generation legit???? Louis Pasteur to the rescue!!!

33 Louis Pasteur performed a series of important experiments that put spontaneous generation to rest His S-shaped flasks were the innovation that finally helped to disprove spontaneous generation

34 The debate over spontaneous generation helped to give rise to the scientific method Make an observation Generate hypothesis (statement that can tested) Hypothesis is then tested through experimentation Results support or don t support hypothesis

35 Sure, you ve heard about the scientific method. But do you really KNOW what science is all about??? TRUE or FALSE?? Science is the search for the truth? FALSE Once a fact is shown by science, it cannot be disproved. FALSE Science is not a system of beliefs. TRUE

36 To set up good experiments, you need to keep in mind several factors Hypothesis = an explanation for an observation that can be proved or disproved through experimentation Bad hypothesis: Grass is green Good hypothesis: The grass is green because of chlorophyll Variable = a factor that exists in different amounts or types (can be changed by researcher (independent) or is being measured during experiment (dependent) Controls = groups that are treated the same as experiment except for one variable

37 Let s help Pasteur science himself out of his next big question What s ruining all of the wine??? It was known that fermentation led to the production of alcohol, but sometimes the process produced acid too. Known: Fermenting grapes makes wine Fermentation generally takes place in absence of air Both bacteria and yeast were found in bad wine

38 Figure 1.14 How Pasteur applied the scientific method in investigating the nature of fermentation.

39 Pasteur s experiments led to the development of pasteurization Pasteurization = Process of heating liquids just enough to kill most bacteria, but not to destroying the physical properties of the product This led to the field of industrial microbiology where microbes are used to make products for us

40 Pasteur developed the germ theory of disease Germ theory: microorganisms can be responsible for diseases Robert Koch (German doctor) Championed the etiology (the study of the cause of disease) Was successful in demonstrating the fatal disease Anthrax, was caused by a microorganism

41 Koch s came up with a series of steps to prove that an agent can cause a disease Koch s postulates (followed today): Suspected causative agent must be found in every case of the disease and be absent from healthy hosts Agent must be isolated and grown outside the host When agent is introduced into a healthy, susceptible host, the host must get the disease Same agent must be found in the diseased experimental host

42 Many additional great techniques came out of Koch s lab that are still used today Flagella stain Use of sterilized inoculation loop to transfer bacteria Use of Petri dishes to hold solid media to grow microbes

43 The concept of pure culture and isolation of bacteria also came out of Koch s work

44 Hans Gram (who worked with Koch) developed one of the most important microbial stains Gram-positive Gram-negative Hans Christian Gram

45 Many people contributed to new ideas of preventing infection and disease First aseptic technique in medicine; cleaned wounds with phenol Introduced aseptic technique to nursing, founded nursing school Made the first vaccine for smallpox using cowpox virus Joseph Lister Florence Nightingale Edward Jenner

46 The study of microbiology is very important today to many fields of science Biochemistry Genetics, molecular biology, biotechnology (gene therapy) Bioremediation (cleaning up environmental waste) Disease