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Unformatted text preview: 1 Selective and/or Differential Media Experiments Ex. 4-1: Mannitol Salt Agar (MSA) (pgs108-110) Purpose : To isolate and differentiate pathogenic organisms like Staphylococcus aureus . Mannitol Salt Agar (MSA) is a selective and differential media.- contains mannitol, 7.5% NaCl, and the pH indicator Phenol red- in general, organisms can not grow on this amount of salt. Thus, the media is selective for Staphylococcus species.- Some species of Staph (pathogenic) have the ability to ferment mannitol.- Acid is produced if mannitol fermentation occurs. Phenol Red can show the decrease in pH. It is yellow when the pH is below 6.8, red at pH 7.4-8.4, and pink at above 8.4.- If the organism is nonpathogenic, then it will grow well on MSA, but will not ferment mannitol.- If the organism does not grow well, then it is probably not Staph . Materials: (per group of students) TSB cultures of: 1 Mannitol Salt Agar (MSA) plate Staphylococcus aureus 1 TSA plate (to serve as a control) Staphylococcus epidermidis...
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This note was uploaded on 04/17/2008 for the course BIO 2200 taught by Professor Choong-minkang during the Fall '08 term at Wayne State University.
- Fall '08