Microbiology 150 lab 3 selective vs differential


This weak base raises the pH of the media above 8. In order to use these starches as a carbon source, bacteria must secrete a-amylase and oligo-1,6-glucosidase into the extracellular space.

Consult listed references for more information. This test is performed on Gram-positive, catalase positive species to identify the coagulase positive Staphylococcus aureus. Additional biochemical and serological tests are required for complete identification.

Compare this growth to growth in your other plates. Blood Agar is a bacterial growth medium that can distinguish normal from pathogenic bacteria based on the effect of bacterial hemolytic exotoxins on red blood cells.

It is recommended that these tests be done before the Gram stain and the KOH tests. If the sealed tube remains green, but the unsealed becomes yellow, it has oxidative fermentation. If growth has a yellow halo around it, the species ferments the sugar mannitol If the organism is a Staphylococcus, it is possibly pathogenic S.

List of culture media used in microbiology with their uses

Bile Esculin Test In this medium there is bile and esculin. Cytochrome c oxidase Cytochrome c oxidase picks up electrons and passes them to a pigment called cytochrome c, which is part of the electron transport pigment system needed for aerobic respiration.

Here we will use a general purpose media to compare the growth on the selective and differential media. As a result, an arrow of beta-hemolysis is produced between the two streaks.

In organisms capable of utilizing citrate as a carbon source, the enzyme citrase hydrolyzes citrate into oxaoloacetic acid and acetic acid. It is unlikely that anyone could isolate such a rare specimen from a mixed sample. The degree of hemolysis by these hemolysins is helpful in differentiating members of the genera Staphylococcus, Streptococcus and Enterococcus.

The alkaline pH turns the pH indicator bromthymol blue from green to blue. Now reflame your loop important.


A nonselective medium should also be inoculated. It tests the ability of an organism to do several things: If the pH indicator methyl red is added to an aliquot of the culture broth and the pH is below 4. If growth has no yellow halo around it background is not yellowthe species does not ferment the sugar mannitol.

The organism pictured on the far left is positive for hydrogen sulfide production. This stab allows for the detection of streptolysin O, a specific hemolysin produced by Streptococcus pyogenes.

Differential and Selective Bacterial Growth Media Lab Exercise Main Page Differential Media from the Virtual Interactive Bacteriology Laboratory. Schauer, Cynthia () Applied Microbiology HCR Laboratory Manual, Kalamazoo Valley Community College.

Selective Bacterial Growth Media Specialized media can be selective; formulated to grow only certain microbes while inhibiting the growth of others.

What are the selective and differrential mediums in culture of bacteria ?

For example MacConkey’s (MAC) selective bacterial growth medium will only grow Gram-negative bacteria. Learn Microbiology Lab Exam 2 Study Guide facts using a simple interactive process (flashcard, matching, or multiple choice).

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LABORATORY IN MICROBIOLOGY BIMM Fall Mandatory Lecture: T/Th – am; Sequoyah Hall Selective and Differential Media 7 Hemolysis of Red Blood Cells 10 BIMM Microbiology Lab Dr.


Microbiology Tests

Chilukuri i Week /Lab Date Experiment Reports, Quizzes. vi Course Policies Lab safety/lab procedures: Students are expected to follow the rules for laboratory safety & procedures described in detail on pages ix-x.

An online safety quiz (on Canvas) must be taken before the start of the 2nd lab. Each student may take the quiz as many times as necessary. Methods of Culturing selective and differential MSA – Selective (7% NaCl) for Staphylococcus 23 Fig.

Summary of Biochemical Tests

The parts of a student laboratory microscope 24 Fig. 3.

Microbiology 150 lab 3 selective vs differential
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Blood Agar Bacterial Growth Medium