Microbiology

BACTERIA
1. Prokaryotes with peptidoglycan which composes Gram-positive cell walls
2. Anaerobic or aerobic
3. 1 to 10um
4. Chromosomes pulled apart by attachments to inner membrane
5. External cell wall
6. RNA and protein synthesized in the single compartment
7. No organelles
8. No endo or exo cytosis
9. Rods or cocci
10. BACTERIAL SPORE FORMATION
  1. Gram-positive bateria in rod shape can produce spores
  2. Spores are highly resistant to chemicals, desiccation and nutrient depletion
  3. Heat resistant so can survive pasteurisation/cooking
  4. Dormant but germinate when the environment is optimal
11. BACTERIA ASSOCIATED WITH FOOD
  1. Pathogenic bacteria: food poisoning
    1. Gram negative rods (Enterobacteriaceae non-spore forming rods) E.G. E coli.
    2. Gram negative rods (Pseudomonads)
    3. Gram positive rods (Clostridia)
  2. Cultured bacteria
    1. Gram positive rods (Lactobactilli - found in yoghurt)
12. BACTERIAL STRUCTURE AND THE GRAM STAIN
  1. Three types of cell wall layers; Gram positive, Gram negative and Acid fast
  2. GRAM STAIN
    1. 1. Add bacteria to microscope slide
    2. 2. Set and stain with Crystal Violet (only retained in Gram positive cell walls
    3. 3. Wash and stain Iodine
    4. 4. Wash and destain with Ethanol
    5. 5. Counterstain with Safranin
13. BINARY FISSION
  1. Asexual
  2. Genomic DNA replicates
  3. Cell doubles its mass
  4. In ideal growth conditions E. coli is capable of undergoing one cell cycle every 20 minutes
14. CONTROLLING PATHOGENIC BACTERIA
  1. Sterilisation
    1. Complete destruction/elimination of all viable organisms
    2. E.G. spores, sterile objects, heat, radiation, chemicals and physical removal of cells
  2. Disinfection
    1. Kills, inhibits or removes organisms that may cause disease
    2. Vegetative microorganisms but not spores
    3. Inanimate objects (not safe for living tissues)
  3. Decontamination with biocides
    1. Kills, inhibits or removes organisms that may cause disease
    2. Vegetative microorganisms and potentially spores
    3. Very strong
    4. Used for inanimate objects, healthcare
EUKARYA
1. 10 to 100um
2. Anaerobic or aerobic
3. Internal cytoskeleton
4. Long linear DNA
5. RNA synthesized and processed in nucleus; proteins synthesized in cytoplasm
6. Endo and exo cytosis
7. Chromosomes pulled apart by attachments to cytoskeletal components
8. FUNGI
  1. Three groups: Moulds, Yeasts and Mushrooms
  2. Cell walls made of chitin
  3. Fungal cell walls made of hyphae
  4. Together these make a mycelium
  5. Form branches
  6. Can reproduce sexually or asexually- fungal spores
  7. Yeast 'bud'
ARCHAEA
1. Prokaryotes without peptidoglycan
VIRUSES
1. Contains either RNA or DNA and replicates in cells
2. Has an extracellular state
PRIONS
1. Entirely protein
2. No nucleic acids
3. Infectious
4. Causes disease in animals
5. Currently not found in plants
MICROBIAL NUTRITION
1. AUTOTROPHS
  1. Capable of synthesising complex organic molecules from a simple non-organic molecules
2. HETEROTROPHS
  1. Use organic molecules such as carbon
GROWING MICROBES IN THE LAB
1. OPTIMAL CONDITIONS
  1. Nutrient source
  2. Optimal temperature
  3. Water availability
  4. pH
  5. Gaseous atmosphere
  6. No antimicrobials (agent that kills microorganisms or stops their growth)
2. CULTURE
  1. 1. Nutrient source
    1. Carbohydrate - sugars
    2. Proteins/amino acids - meat/yeast extracts
    3. Minerals/Vitamins
  2. 2. Broth culture
    1. Test tubes/bottles
  3. 3. Solid media
    1. Test tubes/bottles
  4. Culture media can be formulated to:
    1. Meet nutritional requirements of certain bacteria
    2. Selectively grow bacteria, inhibit others
    3. Be diagnostic
MICROBES
1. MICROBIAL GROWTH IN LIQUID (broth)
  1. When bacteria grow in a liquid broth the normally follow a standard pattern of growth
2. MICROBES AND TEMPERATURE
  1. High temperatures cause:
    1. Membrane disruption
    2. Protein denaturation
    3. For every 10C increase in temperature the metabolic rate and growth rates approximately double
  2. Low temperatures cause:
    1. Adaptations to maintain membrane fluidity
    2. Slow metabolic processes
    3. Slow growth rates

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Microbiology

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