Lab Three PT 3

• EnteroPluri Test

  • used for rapid identification of unknown enteric bacteria
  • multi-test system that contains a series of biochemical tests which evaluate metabolic properties of a sample
  • 12 compartments filled with agar-based media
  • 15 biochemical tests
• Enterobacteriaceae Family

  • members of enterobacteriaceae family (found in digestive tract)
  • all gram-negative, anaerobic rods with simple nutritional requirements
  • some benign and some pathogenic
• Sugar Fermentation

  • if fermenting: end products are acid or acid + gas
  • production of acid = pH change indicated by color change
  • production of gas = lifting of wax layer in glucose
• Decarboxylase

  • bacterial enzymes removing carboxyl (COOH) groups from amino acids = decarboxylation
  • 3 enzymes used for enteric bacteria: lysine, ornithine, arginine
  • result in alkaline end-products (amine) and CO2 which raise pH
• Voges-Proskauer Test

  • used to distinguish acetoin-producing bacteria
  • production of acetoin: reacts with alpha-napthol and KOH to produce red color: positive
  • production of no acetoin: alpha-napthol and KOH to produce copper color: negative
• Urea

  • test for production of urease (splits urea into ammonia and carbon dioxide)
  • production of urease/ammonia: phenol red pH indicator will turn pink
• How to identify an unknown?

  • Determine positive or negative
  • Assign numerical scores: put together
  • Check in book