THE VIRTUAL EDGE: Lab 5 Cultivation of Bacteria I

Types of media:

Glucose Salts Agar (GSA): is a simple, defined medium.  Only organisms that can make all their cellular components from glucose and inorganic salts are able to grow on this medium.

Tryptic Soy Agar (TSA): is a rich, undefined medium containing products of an enzymatic digest of protein and soy product.  Organisms that require vitamins or other growth factors are able to grow on TSA.

Eosin Methylene Blue (EMB) Agar: is a selective AND a differential medium.  The selective components are the eosin and methylene blue dyes that inhibit the growth of Gram-positive bacteria and permit the growth of Gram-negative enteric rods.  The differential component of the medium is lactose, which is a sugar that some organisms can ferment as an energy source.  Organisms that ferment lactose produce dark purple (sometimes shiny) colonies and those that cannot, produce white or very light pink colonies.



Lab 5 / Aseptic Technique / Nutritional Requirements for the Cultivation of Bacteria / Enumeration of Bacteria / Dilutions / Lab 5 Organisms

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