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  1. 1. Classification of Microbes <ul><li>What are Microbes? </li></ul><ul><li>A microbe is any living thing that spends its life at a size visible sometimes only with a microscope. </li></ul><ul><li>It is too tiny to be seen with the naked eye. Microbes are the oldest form of life on Earth. </li></ul><ul><li>The term microbe is short for microorganism, which means small organism. </li></ul><ul><li>To help people understand the different types of microbes, they are grouped or classified in various ways. </li></ul><ul><li>Microbes are very diverse and represent all the great kingdoms of life. </li></ul>
  2. 2. Prokaryotes (Bacteria) <ul><li>Eubacter &quot;True&quot; bacteria </li></ul><ul><ul><li>Human pathogens </li></ul></ul><ul><ul><li>Clinical or environmental </li></ul></ul><ul><ul><li>One kingdom </li></ul></ul><ul><li>Archaea </li></ul><ul><ul><li>Environmental organisms </li></ul></ul><ul><ul><li>Second kingdom </li></ul></ul>
  3. 3. Eukaryotes <ul><li>Other cell-based life e.g. </li></ul><ul><li>Plants </li></ul><ul><li>Animals </li></ul><ul><li>Fungi </li></ul>
  4. 4. Prokaryotic vs. Eukaryotic Cells <ul><li>Prokaryotic cells </li></ul><ul><ul><li>No Nucleus </li></ul></ul><ul><ul><li>No Organelles </li></ul></ul><ul><ul><li>Cell Wall of peptidoglycan </li></ul></ul><ul><ul><li>Binary Fission </li></ul></ul><ul><ul><li>1 circular chromosome </li></ul></ul><ul><li>Eukaryotic Cells </li></ul><ul><ul><li>Nucleus </li></ul></ul><ul><ul><li>Organelles </li></ul></ul><ul><ul><li>If cell wall, Cellulose or chitin </li></ul></ul><ul><ul><li>Mitosis </li></ul></ul><ul><ul><li>Linear chromosomes </li></ul></ul>
  5. 5. <ul><li>Here is an outline of the major groups of microorganisms: </li></ul><ul><li>Viruses </li></ul><ul><li>Bacteria </li></ul><ul><li>Algae </li></ul><ul><li>Fungi </li></ul><ul><li>Protozoa </li></ul>
  6. 6. Bacteria <ul><li>Bacteria consist of only one cell, but they're a very complex group of living things. </li></ul><ul><li>Some bacteria can live in temperatures above the boiling point and in cold below the freezing point. </li></ul><ul><li>There are thousands of species of bacteria, but all of them are basically one of three different shapes. </li></ul><ul><li>Some are rod- or stick-shaped; others are shaped like little balls. </li></ul><ul><li>Others still are helical or spiral in shape. </li></ul><ul><li>Some bacteria cells exist as individuals while others cluster together to form pairs, chains, squares or other groupings. </li></ul>
  7. 7. Classification of Microbes <ul><li>Taxonomic Hierarchy For eg: Escherichia coli </li></ul><ul><ul><li>Domain Bacteria </li></ul></ul><ul><ul><li>Kingdom Monera </li></ul></ul><ul><ul><li>Phylum Proteobacteria </li></ul></ul><ul><ul><li> Class Gammaproteobacteria </li></ul></ul><ul><ul><li> Order Enterobacteriales </li></ul></ul><ul><ul><li>Family Enterobacteriaceae </li></ul></ul><ul><ul><li> Genus Escherichia </li></ul></ul><ul><ul><li> Species E. coli </li></ul></ul>
  8. 8. Classification of bacteria <ul><li>There are several approaches to bacterial classification </li></ul><ul><li>A. Morphological classsification . </li></ul><ul><li>Based on morphology bacteria are divided into various groups </li></ul><ul><li>1. Filamentous or higher bacteria- Actinomycetes </li></ul><ul><li>2. True or lower bacteria </li></ul><ul><ul><li> I. Gram positive bacilli </li></ul></ul><ul><li> Aerobes- corynebacterium, bacillus </li></ul><ul><li> Anaerobes-Clostridium, lactobacillus </li></ul><ul><li>II. Gram positive cocci </li></ul><ul><li>III. Gram negative cocci </li></ul><ul><li>IV. Gram negative bacilli or rods </li></ul><ul><li> </li></ul>
  9. 9. Gram-positive rods Gram-negative rods Gram-positive cocci Gram-negative cocci
  10. 10. <ul><li>V. coccobacilli- Brucella </li></ul><ul><li>3. Comma chaped- vibrios </li></ul><ul><li>4. Spirochaetes- Borrelia, Treponema </li></ul><ul><li>5 . Mycoplasmas- Cell wall deficient </li></ul><ul><li>6 . Ricketsia and chlamydia- Obligate parasites </li></ul>
  11. 11. <ul><li>B.Nutritional classification </li></ul><ul><li>I. Based on Energy requirements </li></ul><ul><li>Phototrophs: Derive energy from sunlight </li></ul><ul><li>Chemotrophs: Use Chemicals </li></ul><ul><li>II. Based on ability to synthesize essential metabolites </li></ul><ul><li>Autotrophs: Synthesize organic coumpounds from carbon dioxide and nitrogen </li></ul><ul><li>Heterotrophs: Depend on preformed organic compounds eg pathogens </li></ul><ul><li>III. Based on oxygen requirements </li></ul><ul><li>Aerobes </li></ul><ul><li>Anaerobes </li></ul>
  12. 12. Gram-positive cocci Anaerobic Gram-positive rods Anaerobic Gram-negative rods Anaerobic Gram-positive cocci Anaerobic Gram-negative cocci
  13. 13. <ul><li>IV. Based on temperature </li></ul><ul><li>Psychrophiles: Below 20°C </li></ul><ul><li>Mesophiles: 25-40°C </li></ul><ul><li>Thermophiles: 55-80°C </li></ul><ul><li>C . Biochemical classification : </li></ul><ul><li>LF </li></ul><ul><li>NLF </li></ul><ul><li>LLF </li></ul><ul><li>Production of Indole, H2S, Catalase, Oxidase, Urease etc </li></ul>
  14. 14. <ul><li>D. Classification based on staining reaction : </li></ul><ul><li>I. Based on Grams stain : </li></ul><ul><li> Gram positive bacteria </li></ul><ul><li>Gram negative bacteria </li></ul><ul><ul><li>II. Based on acid fast stain : </li></ul></ul><ul><li>Acid fast bacilli </li></ul><ul><li>Non acid fast bacilli </li></ul>
  15. 15. <ul><li>E. Serological/ antigenic classification </li></ul><ul><li>Microorganism possess many different kinds of antigens, based on which they are classified into </li></ul><ul><li>I. Serovars or Serotype </li></ul><ul><li>II. Sero groups </li></ul>
  16. 16. Major Taxonomic Groups of Bacteria per Bergey’s manual <ul><li>Gracilicutes – gram-negative cell walls, thin-skinned </li></ul><ul><li>Firmicutes – gram-positive cell walls, thick skinned </li></ul><ul><li>Tenericutes – lack a cell wall & are soft </li></ul><ul><li>Mendosicutes – archaea, primitive procaryotes with unusual cell walls & nutritional habits </li></ul>
  17. 17. <ul><li>Assignment: </li></ul><ul><li>Find out what is Bergey’s manual i n detail. </li></ul>