Gelatinase Test and Bacterial Unknowns

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Gelatinase Test and Bacterial Unknowns

• Lab 20

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Experiment

• Gelatinases comprise a family of extracellular
  enzymes produced by some microorganisms to
  hydrolyze gelatin
• The smaller amino acids can then be taken up by
  te bacterial cell for metabolic purposes
• Bacteria is positive for the enzyme and will
  liquify the media
• Bacteria does not secrete the enzyme and the
  media will remain hard
• E. coli
• S. aureus

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HYDROLYTIC ENZYMESEx 5-17 Gelatinase Test

• Teams of 4
• Organisms
• Escherichia coli
• Staphylococcus aureus
• Media
• 2 gelatin tubes
• Put a heavy loopful of the organism all the way
  down to the bottom of the tube

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Using Gelatin

• This media is used to test if bacteria can digest
  the protein gelatin. To digest gelatin, the
  bacteria must make an enzyme called gelatinase.
• To inoculate this media, use a transfer needle to
  stab the gelatin. After incubating the inoculated
  media for at least 48 hrs, transfer the tube into
  a refrigerator. The tube should be completely
  chilled prior to observation.
• If the media is solid after refrigeration then
  the test is negative (the bacteria did not digest
  gelatin). If the media is liquified even after
  refrigeration, then the test result is
  positivethe bacteria is able to digest gelatin.

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results

• Results -examples
• The 'Serratia marcescens' on the left is positive
  for gelatinase production, as evidenced by the
  liquidation of the media.  The 'Salmonella
  typhimurium' on the right is negative, as
  evidenced by the solidity of the media. 

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UN Bacterial Unknowns

• Check your streak plates if you have isolated
  colonies, put them on nutrient slants if not,
  re-streak your unknown
• Media
• 1 2 Nutrient agar slants or 1 Nutrient Agar
  plate