Lecture Objectives: Why study microbiology? What is microbiology? Roots of microbiology

Transcription

1 1 Lecture Objectives: Why study microbiology? What is microbiology? Roots of microbiology Why study microbiology? ENVIRONMENTAL MEDICAL APPLIED SCIENCE BASIC SCIENCE

2 The science of microbiology Microbiology can be highly interdisciplinary Biochem. Ecology Molecular Bio Microbiology Physiology Genetics Geology Chemistry Computer Sci. Engineering What is Microbiology Study of life too small to be seen unaided by eye! Need a microscope to see them <0.1 mm too small to see Using techniques of microbiology!isolate microorganisms!study their characteristics

3 Where to find microbes Ex. 1. In nature: Where to find microbe Ex. 2. In your intestines:

4 Characteristics of a living organism All living organisms are composed of one or more cells the cell theory of life. Viruses are not cellular, and are not considered to be living organisms. They are still considered a microorganism. Characteristics of life Cell: The fundamental unit of living organisms with characteristic functions and structures. Cell functions: 1. Metabolism biochemical reactions catalyzed by enzymes 2. Reproduction

5 Characteristics of life 3. Differentiate! Formation of a spore; part of cell life cycle. 4. Communicate! Or interact by means of chemicals released or taken up Characteristics of life 5. Movement! Living organisms are often capable of self-propulsion 6. Evolve! Cells evolve to display different or new biological properties.

6 Characteristics of life Cells have structures: Cytoplasm aqueous fluid containing enzymes, organelles, chemicals Nuclear area with DNA Cell membrane (plasma membrane) boundary between cell and environment Classifying life Three domains of organisms are now recognized: Bacteria numerous and diverse Archaea many live in extreme environments Eukarya fungi, algae, protozoa, plants, animals

7 Figure 1.6 Tree of Life Prokaryotes Figure 1.7 Drawings of representative microorganisms, as they appear by light microscopy

8 Classifying life: Eukaryotes We are eukaryotes Some are big some are small. Hallmarks of eukaryotes:! Nuclei! Membrane bound organelles Some microbial eukaryotes:! Yeast! Fungi! Protozoa! Diatoms Classifying life: Archaea Archaea are microorganisms No nuclei Different than bacteria! To be discussed later. Often live in extreme environments Mostly non-pathogenic methanoarchaea

9 Classifying life: Bacteria Bacteria are microorganisms Most are harmless No nucleus Pathogenic:! Escherichia coli (E. coli)! Streptococcus (strep throat)! Yersinia pestis (plague)! Salmonella (food poison) Non-pathogenic:! Thermus aquaticus (PCR)! Lactobacillus (dairy products)! Nitrosomonas (fish aquariums) Nitrifying bacteria Let s define a microorganism Microorganism:! Can be eukaryotic, archaeal, or bacterial. Prokaryotes:! Lack membrane-bound nucleus! Self replicate We will focus is on the Prokaryotes! Bacteria and Archaea virus prokaryote Nucleus 2!m

10 History of microbiology Infectious diseases, population control, and antiquity.! Cholera, syphilis, casualties of war, trade. Black Death! 1331 History of microbiology How did people figure out that there were microbes? Major break through was when people could see microorganisms. Antony van Leeuwenhoek ( )! Built the first solar light microscope in 1676.! Magnification 300X

11 Antony van Leeuwenhoek Average guy with extreme curiosity. Excellent eye-sight Key player in advancing the field of microbiology He saw the unseen for the first time! E.g.:! Corpuscle! Bacteria! Spermatozoa! Algae He reported his observations too. In sometimes painful details. Antony van Leeuwenhoek First observation of growing microorganisms. Also anaerobic growth Experimented with pepper water in open and sealed glass tubes. Used is microscope to make is observations.

12 Microbes and disease Greek physician Galen said disease was caused by imbalance of 4 humours:! Blood! Phlegm! Yellow bile! Black bile Fracastoro: (Italy)! Wrote about spread of disease! Proposed epidemics were spread by tiny spores. Pasteur and Sterilization. During the mid 1800 s there were hints that a transferable or infectious agent caused disease. Along came Robert Koch! Showed, without a doubt, that anthrax was caused by a bacterium. John Snow and epidemiology British epidemiologist around 1850 Proposed that cholera might come from water Used surveys and maps Linked the disease to sewage in water Therefore cholera must have come from sewage. Still couldn t prove that is was a caused by a microorganism!

13 Robert Koch--from modest doctor to pioneering microbiologists He was the first to prove that a microbe caused disease. In the blood of animals dying of anthrax there was always one type of bacterium: Bacillus anthracis But, did these bacteria cause the disease? Or did something else cause the disease and then this bacterium came along; take advantage of the weakened animal; and grow? Supplemental Reading on Web Page from Microbe Hunters Koch s Postulates

14 Koch s Postulates: Defined 1. The suspected pathogenic organism should be present in all cases of the disease and absent from healthy animals 2. the suspected organism should be grown in pure culture 3. Cells from a pure culture of the suspected organism should cause disease in a healthy animal 4. The organism should be re-isolated and shown to be the same as the original. Koch s Postulates: Part II 1. Blood of diseased animal. 2. Injected into healthy animal 3. Found same bacterium in the blood 4. Repeat 5. What s the problem: How do you know disease comes from one bacterium? 10 9 cells/ml. Is there only 1 type in there? How do we address this problem? We need a way to separate individual bacteria. Then we need to culture the isolate and then repeat postulate #3. Solution:! Dilute sample to one cell! Use Koch s method for isolating individual bacteria! The streak plate This was another major advancement in the field of microbiology

15 The Streak Plate Need a solid surface to keep bacteria from moving away.! Agar, petri dish Means of separating cells.! Sterile stick or metal loop Sterilization method! Heat Once all these techniques were developed, Koch went on to isolate the bacteria that caused Anthrax, Tuberculosis, and Cholera. He received the 1905 Nobel Prize for the Tb work Study Questions: 1. Why was the microscope key to microbiology? 2. What are the 6 characteristics of living cells? Which characteristics are universal? 3. Which of the 3 Domains contain microorganisms? How do microorganisms within these domains differ and how are they the same? 4. What are Koch's postulates and how are they used? 5. What is pure culture, and why is so important for microbiology? What would be different if Koch didn't start with a pure culture? 6. How did solid media help with obtaining pure cultures? 7. What is sterile technique, and why is it important? In other words, what would happen if sterile techniques weren't used?