FINALS

• Culture


  Growth of microorganism on culture medium
• Culture medium


  Liquid, semi-solid or solid preparation utilized to observe growth pattern of microorganism as well as for transport and storage

  
• Types of cultures


  • Pure culture (one genus)
  • Mixed culture (more than 2 genus and species)
  • Stock culture (for academic or industrial purposes)
• Classification of culture medium according to consistency

  • Liquid medium (BHI, TSB and Thioglycollate)
  • Semi-solid medium (contains 0.5 to 1% agar, a sulfated polymer made up of D-galactose, 3,6-anhydro-L-galactose and D-glucoronic acid, usually derived from algae, ex. SIM)
  • Solid medium (2-3% agar, ex. TSI, Mac Conkey and Chocolate agar)
• Classification of culture medium according to composition

  • Synthetic or Defined medium (all substances are known to the user, used for research purposes)
  • Non-synthetic or complex medium (composed of some unknown substances like peptones, meat and yeast extracts, ex. Nutrient broth, TSB and Mac Conkey agar)
  • Tissue culture medium (to isolate obligate intracellular bacteria like Rickettsia, Chlamydia, ex. W138, HELA 229 cells and Mc Coy cells)
• Classification of culture medium according to use

  • Simple media (routinely used in the lab and without added supplement, ex. Nutrient Agar (NA) and broth, TSB)
  • Enrichment media (used to propagate the growth of certain microorganisms, ex. Alkaline peptone water, Selenite F, BCYE, TMA)
  • Enriched media (with added supplement necessary for growth of organism, solid type media, ex. BAP, CAP, CAP with horse blood)
  • Differential media (allows visualization of metabolic differences between group of species of bacteria, ex. Mac Conkey, BAP, EMB, HE Agar)
  • Selective media (incorporated with antibiotics or inhibitory substances to inhibit growth of other organisms while promoting the growth of the desired organism, ex. HE agar, Mac Conkey, XLD Agar, Bismuth Sulfite Agar, MSA (7.5% salt))
  • Special media (to isolate specific type of bacteria, ex. LJ medium, TCBS)
• Inhibitory substances used in selective media

  • Crystal/gentian violet
  • Basic fuchsin
  • Bile salt
  • Potassium tellurite
  • Sodium azide
  • Alcohol
  • Chloral hydrate
• Generation


  Doubling of cell number
• Generation time/Doubling time


  The time required for a bacteria to double its population
• Phases of bacterial growth curve

  • Lag phase (the period wherein there is no cell division; no abrupt increase in cell number, the phase of adjusting to new environment)
  • Log phase (the period wherein organisms are actively growing and dividing, the period wherein microorganisms are utilized in biochemical testing and are sensitive to antimicrobial agents)
  • Stationary phase (the period wherein there is a balance between cell division and dying organisms, metabolic activities of surviving cells slow down and nutrients are becoming limited, the phase wherein dead debris are starting to accumulate)
  • Death phase (Cessation of bacterial growth, the number of cell death exceeds the number of living microorganisms)
• Transverse binary fission


  Most common asexual reproductive process whereby a single cell divides into 2 daughter cells
• Not all bacteria have the same generation time