sugar and the medium will remain red around the colonies. Protocol: Blood agar is often used to isolate Label the bottom of one TSA, MSA, S. and many strains will lyse red Blood Agar and Bile Esculin Agar plate aureus blood cells producing a clear zone as shown in the diagram below. around the colony. This lysis is not Essentially you are dividing the plate diagnostic for as not all strains into 4 regions. S. aureus produce hemolysins. See Figure 1. Below One other characteristic that some strains of exhibit is the Figure 1. S. aureus production of a yellow-golden pigment. Media for Growth of Streptococci Some members of this genus are a bit more particular about their nutritional requirements and seem to grow best on slightly more enriched media, although most will grow on BHI agar or TSA. Most all species and strains of streptococci will grow well on blood agar. The pattern of Hemolysis seen with the various species is useful for classification and identification. SWAB each organism onto the appropriate region of the plate. You are Bile Esculin agar is useful isolation and NOT trying to get isolated colonies. identification of the group D streptococci. This group will will NOTE - when you turn the plate upside- hydrolyze esculin causing the media to down to streak it, the letters will blacken. be inverted!! Materials: Repeat for the other plates cultures of S. aureus, S. epidermidis, S. pyogenes, S. faecalis On a Blood agar plate ONLY, 1 MSA plates Swab the half of the plate with Sf and 2 Blood agar plates half the plate with Spy. Place a 1 Bile Esculin agar plates bacitracin (B) on each organism’s 1 TSA plates side of the plate. 3 tubes of plasma (for Coagulase Test) Gram stain all of the organisms and Hydrogen peroxide record your observations in Table 1. Pasteur pipettes Bacitracin disks (B disk) Sterile swabs
sugar and the medium will remain red around the colonies. Blood agar is often used to isolate S. aureus and many strains will lyse red blood cells producing a clear zone around the colony. This lysis is not diagnostic for S. aureus as not all strains produce hemolysins. One other characteristic that some strains of S. aureus exhibit is the production of a yellow-golden pigment. Media for Growth of Streptococci Some members of this genus are a bit more particular about their nutritional requirements and seem to grow best on slightly more enriched media, although most will grow on BHI agar or TSA. Most all species and strains of streptococci will grow well on blood agar. The pattern of Hemolysis seen with the various species is useful for classification and identification. Bile Esculin agar is useful isolation and identification of the group D streptococci. This group will will hydrolyze esculin causing the media to blacken. Materials: cultures of S. aureus, S. epidermidis, S. pyogenes, S. faecalis 1 MSA plates 2 Blood agar plates 1 Bile Esculin agar plates 1 TSA plates 3 tubes of plasma (for Coagulase Test) Hydrogen peroxide Pasteur pipettes Bacitracin disks (B disk) Sterile swabs Protocol: Label the bottom of one TSA, MSA, Blood Agar and Bile Esculin Agar plate as shown in the diagram below. Essentially you are dividing the plate into 4 regions. See Figure 1. Below Figure 1. SWAB each organism onto the appropriate region of the plate. You are NOT trying to get isolated colonies. NOTE - when you turn the plate upside- down to streak it, the letters will be inverted!! Repeat for the other plates On a Blood agar plate ONLY, Swab the half of the plate with Sf and half the plate with Spy. Place a bacitracin (B) on each organism’s side of the plate. Gram stain all of the organisms and record your observations in Table 1.
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